university of groningen the role of neutral hydrogen in the life ......chapter 5 the hi absorption...

University of Groningen

The role of neutral hydrogen in the life of galaxies and AGNGereb, Katinka

IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.

Document VersionPublisher's PDF, also known as Version of record

Publication date:2014

Link to publication in University of Groningen/UMCG research database

Citation for published version (APA):Gereb, K. (2014). The role of neutral hydrogen in the life of galaxies and AGN: A spectral stacking analysis.[S.n.].

CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).

Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.

Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.

Download date: 29-05-2021

https://research.rug.nl/en/publications/the-role-of-neutral-hydrogen-in-the-life-of-galaxies-and-agn(851c71b8-337a-438b-9b8c-fe010f3cdae1).html

Chapter 5The HI absorption ‘Zoo’

– K. Geréb, F. Maccagni, R. Morganti, T. Oosterloo –Submitted to Astronomy & Astrophysics

AbstractWe present the analysis of the H I absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H Iabsorption in 32 objects (30% of the sample). In a previous paper, we performed a spectralstacking analysis on the radio sources, while here we characterize the absorption spectra of theindividual detections using the recently presented busy function (Westmeier et al. 2014), anefficient way of fitting both asymmetric and Gaussian H I profiles.

The H I absorption spectra show a broad variety of widths, shapes and kinematical proper-ties. The Full Width Half Maximum (FWHM) of the detections ranges between 32 km s−1 <FWHM < 570 km s−1, whereas the Full Width at 20% of the peak intensity (FW20) varies be-tween 63 km s−1 < FW20 < 825 km s−1. We quantify the asymmetry of the lines by measuringthe velocity offset |∆vCP| between the H I peak and the line centroid (measured at 20% of themaximum). Based on the different shapes and widths of the H I lines, we separate our sample inthree groups: narrow lines (FWHM < 100 km s−1), intermediate (FWHM < 200 km s−1) andbroad profiles (FWHM > 200 km s−1). In each group we study the kinematical and radio sourceproperties of the detections, with the goal of identifying different morphological structures ofH I. Narrow lines at the systemic velocity are likely produced by regularly rotating H I disks.In the sample of detections, 31% of the lines are narrow. More H I disks can be present amongintermediate FWHM lines with up to 63% detection rate, however the H I in these sources ismore unsettled. Among the broadest lines, 45% of the profiles appear blueshifted, while a lowerfraction, 9% are redshifted. Broad lines show large asymmetries up to |∆vCP| ∼ 250 km s−1,and we note that symmetric broad lines are missing from our sample. The combination of broadwidths and lack of symmetry could suggest that these profiles are tracing unsettled gas.

We find three new cases of blueshifted broad wings (with FW20 & 500 km s−1); along withthe high radio power of their AGN, these detections are good candidates for being H I outflows.Together with the known cases of outflows already included in the sample (3C 293 and 3C 305),the detection rate of H I outflows is 5% in the total radio AGN sample. Three of the broadest(up to FW20 = 825 km s−1) detections are associated with gas-rich mergers.

78 chapter 5: The HI absorption ‘Zoo’

Using stacking techniques, in Chapter 4 we show that compact radio sources have higherτ , FWHM and column density than extended sources. Here we measure the H I line param-eters individually in compact and extended sources using the busy function. Blueshifted andbroad/asymmetric lines are often present among compact sources. This result, in good agree-ment with the results of stacking, suggests that unsettled gas is responsible for the larger stackedFWHM detected in compact sources. Such H I gas properties may arise due to jet-cloud inter-actions, as young radio sources clear their way through the rich ambient gaseous medium.

5.1 IntroductionNuclear activity in (radio) AGN is though to be connected to the presence and kinemat-ical properties of the gas in the circumnuclear regions. Observational evidence clearlyshows that interactions between AGN and their ambient gaseous medium do occur. Thus,such interplay is thought to be responsible for the balance between the feeding of theblack hole and feedback processes. H I is one of the components that may play a role inthese processes.

Radio AGN are typically hosted by early-type galaxies (Bahcall et al. 1997; Best et al.2005). In the nearby Universe our knowledge of the cold gas properties of early-typegalaxies has increased in recent years thanks to projects like WSRT-SAURON (Morgantiet al. 2006; Grossi et al. 2009; Oosterloo et al. 2010a) and ATLAS3D (Serra et al. 2012;Young et al. 2011; Davis et al. 2013). In radio-loud AGN, H I absorption studies canbe used to explore the presence and kinematics of the gas. A number of H I absorptionstudies from recent years have provided a better understanding of the H I propertiesof radio galaxies (van Gorkom et al. 1989; Morganti et al. 2001; Vermeulen et al. 2003;Gupta et al. 2006; Curran & Whiting 2010; Emonts et al. 2010).

In the mentioned studies, the morphology and kinematics of H I gas is found to be verycomplex in radio galaxies. H I can trace rotating disks, offset clouds, and complex mor-phological structures of unsettled gas, e.g. infall and outflows. van Gorkom et al. (1989)reported a high fraction of redshifted H I detections in compact radio sources, and they es-timated that infalling H I clouds can provide the necessary amount of gas to fuel the AGNactivity. Later work revealed that not just infalling gas, but also blueshifted, outflowingH I is present in many AGN, and in particular in compact Gigahertz-Peaked Spectrum(GPS) and Compact Steep Spectrum (CSS) sources (Vermeulen et al. 2003; Gupta et al.2006). The structure of compact sources often appears asymmetric in brightness, locationand polarization. Such disturbed radio source properties indicate dynamical interactionsbetween the radio jets and the circumnuclear medium, and this process is likely to bethe driver of fast H I outflows that has been detected in a number of radio galaxies. Allthese properties are consistent with a scenario in which interactions between the radiosource and the surrounding gas have an effect both on the gas and on the radio sourceproperties. It is clear that one needs to disentangle all these phenomena in order tounderstand the intricate interplay between AGN and the gas.

Because AGN and their host galaxies are known to have a broad range of complexH I morphologies, kinematics, gas masses and column densities, future large datasetswill require robust methods to extract and analyze meaningful information that can berelevant for our understanding of the amount and conditions of the gas in radio galaxies.Recently, Westmeier et al. (2014) presented the busy function (BF) for parametrizing H Iemission spectra. The BF is efficient in fitting both Gaussian and asymmetric profiles,

5.2: Description of the sample and observations 79

therefore it is also suitable for fitting the wide variety of absorption lines in our sample.In this paper, we use for the first time the busy function to parametrize and describe

the complex H I absorption properties of a relatively large sample of 32 radio sourceswith H I detections. The total sample of 101 sources was recently presented in Gerebet al. (2014), hereafter referred to as Chapter 4. The main goal of Chapter 4 was tocarry out a spectral stacking analysis of the H I absorption lines and to measure theco-added H I signal of the sample at low τ detection limit. Stacking is very efficient atreproducing the global profile of the stacked spectra, but it does not provide informationon the underlying profile distribution. Here we present the detailed discussion of the H Iabsorption busy fit parameters in relation to the results of stacking.

One interesting finding of the available H I absorption studies presented above is thatthere appears to be a trend between the H I properties and the evolutionary stage ofthe radio source. CSS and GPS sources have been proposed to represent young ( <∼ 104

yr) radio AGN (Fanti et al. 1995; Readhead et al. 1996; Owsianik & Conway 1998). Thehigh H I detection rate in compact CSS and GPS sources has been interpreted as evidencefor a relation between the recent triggering of the AGN activity and the presence of H Igas (Pihlström et al. 2003; Gupta et al. 2006; Emonts et al. 2010; Chandola et al. 2010).

In Chapter 4 we looked at the H I properties of compact and extended sources usingstacking techniques, and we found that compact sources not only have higher detectionrate and optical depth, but also larger profile width than extended sources. We arguethat such H I properties reflect the presence of rich gaseous medium in compact sources,and that the larger FWHM of compact sources is due to the presence of unsettled gas.In the present paper we use the BF to measure the H I parameters of individual compactand extended detections. We discuss the profile parameters of compact and extendedsources in relation to the results of stacking from Chapter 4.

Several examples from the literature show that H I mass outflow rates of a few ×10M⊙yr−1 are associated with fast (∼ 1000 km s−1), radio jet-driven outflows (Morganti et al.1998, 2005), therefore such feedback effects are considered to have major impact both onthe star formation processes in galaxies and the further growth of the black hole. How-ever, at the moment little is known about the frequency and lifetime of such H I outflowsin radio galaxies, and larger samples are needed to constrain the role and significance ofoutflows in the evolution of galaxies. We have not found signatures of broad, blueshiftedwings in the stacked spectra presented in Chapter 4. Here we use the busy fit parametersto identify and characterize new cases of H I outflows.

In this paper the standard cosmological model is used, with parameters ΩΛ = 0.3, Λ= 0.7 and H0 = 70 km s−1 Mpc−1.

5.2 Description of the sample and observationsAs described in Chapter 4, the sample was selected from the cross-correlation of theSloan Digital Sky Survey (SDSS, York et al. 2000) and Faint Images of the Radio Sky atTwenty-cm (FIRST, Becker et al. 1995) catalogs. In the redshift range 0.02 < z < 0.23,101 sources were selected with peak flux S1.4 GHz > 50 mJy in the FIRST catalog. Thecorresponding radio power distribution of the AGN ranges between 1023 – 1026 W Hz−1.

The observations were carried out with the Westerbork Synthesis Radio Telescope(WSRT). Each target was observed for 4 hours. In the case of 4C +52.37, we carried out


8 hour follow-up observations in order to increase the H I sensitivity in the spectra. Thiswill be discussed in Sec. 5.4.2. A more detailed description of the observational setupand the data reduction can be found in Chapter 4.

Because our sample is solely flux-selected, we can expect to have a mix of radiosources with various host galaxies. The radio galaxy sample consists of compact (CSS,GPS, and unclassified) and extended sources in Table 5.0. The sizes of the radio sourcepopulation vary between 4 pc and 550 kpc. Besides radio galaxies, we also find opticallyblue objects with g − r < 0.7 colors. These blue objects are associated with differenttypes of objects, for example gas-rich mergers (UGC 8387, Mrk 273), Seyfert galaxiesand QSOs (Quasi Stellar Objects). To make the AGN sample more homogeneous, weexcluded these sources from the stacking analysis in Chapter 4. In this paper theseobjects are marked by yellow squares in the figures from Sec. 6.5 and discussed in Sec.4.3.

In Chapter 4 we have divided the sample in compact and extended radio sources basedon the NVSS major-to-minor axis ratio vs. the FIRST peak-to-integrated flux ratio. Thesame classification is used here.

5.3 Results

We detect H I absorption in 32 of the observed galaxies, and 24 of these are new detections(see notes on individual sources in Appendix 5.8.1). The H I profiles in Fig. 5.2 show avariety of complex shapes and kinematics. The H I lines are separated in three groupsbased on the profile analysis that will be discussed in Sec. 5.3.1 and Sec. 5.3.2. As wemention in Chapter 4, the τ and N(H I) range of detections is quite broad, spanning twoorders of magnitude between a few × (1017 – 1019) (Tspin/cf) cm−2, where Tspin is thespin temperature and cf is the covering factor of the gas. In Table 5.0 we summarize thecharacteristics of the detected sources.

Non-detections and the corresponding 3-σ upper limits are presented in Table 5.2 ofAppendix 5.8.2. The N(H I) upper limits for non-detections were calculated by assum-ing FWHM = 100 km s−1, following the analysis of the profile widths in Sec. 5.3.1.Each detected source is given a number identifier in Table 5.0 and Table 5.2, and werefer to the detections based on this sequential number. In Chapter 4 we discussed theoptical depth and column density properties of the sample, whereas here we focus onthe kinematical properties of the H I lines. Below we study in more detail the width,asymmetry parameters, and the blueshift/redshift distribution of the detections usingthe busy function.

In Chapter 4 we show that statistically, detections and non-detections have a similarflux distribution, implying that detections in our sample are not biased toward brightersources. Here, in Fig. 5.1 we present the radio power distribution of detections andnon-detections. According to the Kolmogorov-Smirnov test, the significance level thatthe two distributions are different is only 10%, implying that statistically detections andnon-detections have a similar radio power distribution. The largest difference betweenthe two distributions (D) is measured at ∼24.6 W Hz−1.

Further notes on the individual detections are presented in Appendix 5.8.1.

5.3: Results 81T

able

5.0:

Cha

ract

erist

ics

ofth

eH

Ide

tect

ions

.Fo

rea

chde

tect

edso

urce

we

list:

1)id

entifi

erth

atw

illbe

used

inth

ete

xt;

2)sk

yco

ordi

nate

s;3)

alte

rnat

ive

nam

eof

the

sour

ces;

4)SD

SSre

dshi

ft;5

)1.

4G

Hz

flux

dens

ity;6

)1.

4G

Hz

radi

opo

wer

;7)

radi

om

orph

olog

y;8)

radi

oso

urce

size;

9)pe

akop

tical

dept

h;10

)col

umn

dens

ity.

The

radi

om

orph

olog

yab

brev

iatio

nsin

colu

mn

7ar

eas

follo

wsC

:com

pact

inou

rse

lect

ion,

E:ex

tend

edin

our

sele

ctio

n,C

SO:C

ompa

ctSy

mm

etric

Obj

ect,

CSS

:Com

pact

Stee

pSp

ectr

umso

urce

,CJ:

Cor

e-Je

t,C

X:c

ompl

exm

orph

olog

y,U

:unr

esol

ved,

M:m

erge

r,Q

SO:q

uasa

r,FS

RQ

:Fla

tSp

ectr

umR

adio

Qua

sar.

Iden

tifier

RA

,Dec

Nam

ez

S 1.4

GH

zP 1

.4G

Hz

Rad

ioSi

zeτ p

ea

kN

(HI)

mJy

WH

z−1

Mor

phol

ogy

(kpc

)10

18(T

spin

/cf)

cm−

2

#1

07h5

7m56

.7s

+39

d59m

36s

B3

0754

+40

10.

0657

7792

23.9

8C

SS0.

25(K

)0.

042

9.4

#2

08h0

6m01

.5s

+19

d06m

15s

2MA

SXJ0

8060

148+

1906

142

0.09

7882

142

24.5

4E

-0.

099

26.9

#3

08h0

9m38

.9s

+34

d55m

37s

B2

0806

+35

0.08

2493

142

24.3

8C

J(E

)13

9(Bo)

0.00

91.

0#

408

h36m

37.8

s+

44d0

1m10

sB

308

33+

442

0.05

542

134

23.9

9C

SO?

1.7(d

V)

0.01

61.

9#

508

h43m

07.1

s+

45d3

7m43

sB

308

39+

458

0.19

1947

331

25.5

4C

SO0.

14(H

)0.

273

34.5

#6

09h0

9m37

.4s

+19

d28m

08s

Mrk

1226

0.02

7843

6323

.05

FSR

Q?

0.00

8(H)

0.11

923

.3#

709

h35m

51.6

s+

61d2

1m11

sU

GC

0510

10.

0393

8614

823

.73

E(M

)0.

048(L

)0.

073

53.6

#8

10h2

0m53

.7s

+48

d31m

24s

4C+

48.2

90.

0531

5282

23.7

4E

(X-s

hape

d)-

0.05

09.

3#

910

h53m

27.2

s+

20d5

8m36

sJ1

0532

7+20

5835

0.05

2639

7923

.72

C-

0.02

33.

9#

1011

h20m

30.0

s+

27d3

6m11

s2M

ASX

J112

030+

2736

100.

1125

1617

724

.76

C-

0.14

715

.6#

1112

h02m

31.1

s+

16d3

7m42

s2M

ASX

J120

2311

2+16

3741

40.

1195

3282

24.4

8C

-0.

042

7.4

#12

12h0

5m51

.4s

+20

d31m

19s

NG

C40

93-M

CG

+04

-29-

020.

0237

8980

23.0

1C

-0.

034

5.2

#13

12h0

8m55

.6s

+46

d41m

14s

B3

1206

+46

90.

1009

5569

24.2

5E

550(M

)0.

052

2.6

#14

12h3

2m00

.5s

+33

d17m

48s

B2

1229

+33

0.07

8819

9424

.16

FRII

-0.

034

5.6

#15

12h4

7m07

.3s

+49

d00m

18s

4C+

49.2

50.

2069

111

4026

.15

CSS

6(S)

0.00

20.

5#

1612

h54m

33.3

s+

18d5

6m02

s2M

ASX

J125

433+

1856

020.

1154

476

24.4

2C

SO0.

017(H

)0.

068

6.3

(B)

Bes

wic

ket

al.(

2004

);(B

o)B

ondi

etal

.(20

04);

(C)

Car

illi&

Tayl

or(2

000)

;(F

)Fe

rett

i&G

iova

nnin

i(19

94);

(H)

Hel

mbo

ldt

etal

.(2

007)

;(K

)K

uner

t-B

ajra

szew

ska

&La

bian

o(2

010)

;(L)

Lons

dale

etal

.(20

03);

(M)

Mar

chã

etal

.(20

01);

(Ma)

Mac

ket

al.(

1993

);(R

)R

omer

o-C

añiz

ales

etal

.(20

12);

(S)

Saik

ia&

Gup

ta(2

003)

;(T

)Ta

ylor

etal

.(20

07);

(dV

)de

Vrie

set

al.(

2010

).


Tab

le5.

0:-C

ontin

ued.

Iden

tifier

RA

,Dec

Nam

ez

S 1.4

GH

zP 1

.4G

Hz

Rad

ioSi

zeτ p

ea

kN

(HI)

mJy

WH

z−1

Mor

phol

ogy

(kpc

)10

18(T

spin

/cf)

cm−

2

#17

13h0

1m32

.6s

+46

d34m

03s

2MA

SXJ1

3013

264+

4634

032

0.20

552

9725

.07

C-

0.01

83.

2#

1813

h17m

39.2

s+

41d1

5m46

sB

313

15+

415

0.06

6109

246

24.4

2C

X0.

005(d

V)

0.03

17.

0#

1913

h20m

35.3

s+

34d0

8m22

sIC

883,

UG

C83

870.

0230

5897

23.0

7E

(M)

0.98

(R)

0.16

278

.8#

2013

h25m

13.4

s+

39d5

5m53

sSD

SSJ1

3251

3.37

+39

5553

.20.

0755

5137

23.7

1C

SO?

0.01

4(dV

)0.

053

9.3

#21

13h4

0m35

.2s

+44

d48m

17s

IRA

SF1

3384

+45

030.

0654

4236

23.5

7C

J0.

0041

(dV

)0.

260

20.3

#22

13h4

4m42

.1s

+55

d53m

13s

Mrk

273

0.03

734

132

23.6

3E

(M)

0.14

8(C)

0.09

176

.2#

2313

h52m

17.8

s+

31d2

6m46

s3C

293

0.04

5194

3530

25.2

3FR

I28

0(B)

0.05

714

.5#

2414

h22m

10.8

s+

21d0

5m54

s2M

ASX

J142

210+

2105

540.

1914

7784

24.9

4C

-0.

048

10.1

#25

14h3

5m21

.7s

+50

d51m

23s

2MA

SXJ1

4352

162+

5051

233

0.09

9694

141

24.5

5U

0.27

(dV

)0.

013

4.7

#26

14h4

9m21

.6s

+63

d16m

14s

3C30

5-I

C10

650.

0416

7725

0025

.01

FRI

-0.

005

1.5

#27

15h0

0m34

.6s

+36

d48m

45s

2MA

SXJ1

5003

4+36

4845

0.06

6101

6123

.81

QSO

-0.

190

35.3

#28

15h2

9m22

.5s

+36

d21m

42s

2MA

SXJ1

5292

250+

3621

423

0.09

8934

3823

.97

C-

0.07

525

.1#

2916

h02m

46.4

s+

52d4

3m58

s4C

+52

.37

0.10

5689

577

25.2

2C

SO0.

35(d

V)

0.01

56.

7#

3016

h03m

32.1

s+

17d1

1m55

sN

GC

6034

0.03

402

278

23.8

7E

122(M

a)0.

066

5.6

#31

16h0

3m38

.0s

+15

d54m

02s

Abe

ll21

470.

1097

6110

024

.49

FSR

Q0.

02(T

)0.

125

50.7

#32

16h1

2m17

.6s

+28

d25m

47s

2MA

SXJ1

6121

7+28

2546

0.05

3138

7823

.72

C0.

6(F)

0.06

17.

8

(B)

Bes

wic

ket

al.(

2004

);(B

o)B

ondi

etal

.(20

04);

(C)

Car

illi&

Tayl

or(2

000)

;(F

)Fe

rett

i&G

iova

nnin

i(19

94);

(H)

Hel

mbo

ldt

etal

.(2

007)

;(K

)K

uner

t-B

ajra

szew

ska

&La

bian

o(2

010)

;(L)

Lons

dale

etal

.(20

03);

(M)

Mar

chã

etal

.(20

01);

(Ma)

Mac

ket

al.(

1993

);(R

)R

omer

o-C

añiz

ales

etal

.(20

12);

(S)

Saik

ia&

Gup

ta(2

003)

;(T

)Ta

ylor

etal

.(20

07);

(dV

)de

Vrie

set

al.(

2010

).

5.3: Results 83

22.5 23.0 23.5 24.0 24.5 25.0 25.5 26.0 26.5log(P1.4 GHz) [W/Hz]

0.0

0.2

0.4

0.6

0.8

1.0

Cum

ula

tive fra

ctio

n

DetectionsNon-DetectionsD

Figure 5.1: The 1.4 GHz radio power cumulative fraction of detections and non-detections in the sample of 101 AGN. We measure D = 0.228 for 32 detections and69 non-detections. The source parameters for detection and non-detections are listed inTable 5.0 and Table 5.2, respectively.

5.3.1 Fitting complex H I absorption profiles with the busy func-tion

The sample of absorption lines in Fig. 5.2 is very heterogeneous in terms of line shapeand widths. Thus, it is crucial to develop a uniform method to characterize the proper-ties of this variety of H I profiles. So far, Gaussian fitting has been widely used to deriveabsorption line properties, e.g. the width of the profile, and to determine the pres-ence of multiple components (Vermeulen et al. 2003; Gupta et al. 2006; Curran et al.2011). When multiple peaked profiles occur, like in our absorption sample, Gaussianfitting methods have the disadvantage of having to make an a priori assumption on thephysical conditions of the gas, by choosing the number of components to be fitted. Inthe case of H I integrated emission profiles, an alternative solution has been proposedby Westmeier et al. (2014): the busy function fitting method. The busy function is anheuristic, analytic function, given by the product of two error functions and a polynomialfactor:

B(x)= a4 × (erf[b1w + x − xe] + 1)×(erf[b2w − x + xe] + 1) × (c|x − xp|n + 1)

(5.1)The main advantage of this function is that a proper combination of the parameters

can fit a wide variety of line profiles. When c = 0, the busy function may well approximatea Gaussian profile, while if c = 0, for different values of b1 and b2, an asymmetricdouble horn profile can be reproduced. With the same function it is then possible to


−1000 −500 0 500 1000Velocity [km/s]

−0.008

−0.006

−0.004

−0.002

0.000

0.002

0.004

τ

3

χ2 = 0.64

−1000 −500 0 500 1000Velocity [km/s]

−0.015

−0.010

−0.005

0.000

0.005

τ

4

χ2 = 0.0

−1000 −500 0 500 1000Velocity [km/s]

−0.30

−0.25

−0.20

−0.15

−0.10

−0.05

0.00

0.05

τ

5

χ2 = 1.57

−1000 −500 0 500 1000Velocity [km/s]

−0.14

−0.12

−0.10

−0.08

−0.06

−0.04

−0.02

0.00

τ

10

χ2 = 4.14

−1000 −500 0 500 1000Velocity [km/s]

−0.03

−0.02

−0.01

0.00

0.01

τ

12

χ2 = 1.56

−1000 −500 0 500 1000Velocity [km/s]

−0.05

−0.04

−0.03

−0.02

−0.01

0.00

0.01

0.02

τ

13

χ2 = 1.33

−1000 −500 0 500 1000Velocity [km/s]

−0.06

−0.04

−0.02

0.00

0.02

τ

16

χ2 = 1.21

−1000 −500 0 500 1000Velocity [km/s]

−0.30

−0.25

−0.20

−0.15

−0.10

−0.05

0.00

0.05

τ

21

χ2 = 1.24

−1000 −500 0 500 1000Velocity [km/s]

−0.07

−0.06

−0.05

−0.04

−0.03

−0.02

−0.01

0.00

τ

30

χ2 = 0.84

−1000 −500 0 500 1000Velocity [km/s]

−0.06

−0.04

−0.02

0.00

τ

32

χ2 = 0.95

Figure 5.2: (a) - H I profiles (10 detections) in the narrow region with FWHM < 100km s−1. Red lines represent the BF fits.

5.3: Results 85

−1000 −500 0 500 1000Velocity [km/s]

−0.04

−0.03

−0.02

−0.01

0.00τ

1

χ2 = 1.05

−1000 −500 0 500 1000Velocity [km/s]

−0.08

−0.06

−0.04

−0.02

0.00

0.02

0.04

τ

2

χ2 = 0.69

−1000 −500 0 500 1000Velocity [km/s]

−0.10

−0.08

−0.06

−0.04

−0.02

0.00

0.02

0.04

τ

6

χ2 = 1.3

−1000 −500 0 500 1000Velocity [km/s]

−0.05

−0.04

−0.03

−0.02

−0.01

0.00

0.01

0.02

τ

8

χ2 = 1.48

−1000 −500 0 500 1000Velocity [km/s]

−0.020

−0.015

−0.010

−0.005

0.000

0.005

0.010

0.015

τ

9

χ2 = 1.34

−1000 −500 0 500 1000Velocity [km/s]

−0.03

−0.02

−0.01

0.00

0.01

τ

14

χ2 = 0.88

−1000 −500 0 500 1000Velocity [km/s]

−0.035

−0.030

−0.025

−0.020

−0.015

−0.010

−0.005

0.000

τ

18

χ2 = 1.44

−1000 −500 0 500 1000Velocity [km/s]

−0.04

−0.02

0.00

0.02

0.04

τ

20

−1000 −500 0 500 1000Velocity [km/s]

−0.05

−0.04

−0.03

−0.02

−0.01

0.00

0.01

τ

23

χ2 = 57.92

−1000 −500 0 500 1000Velocity [km/s]

−0.04

−0.03

−0.02

−0.01

0.00

0.01

0.02

τ

24

χ2 = 1.09

−1000 −500 0 500 1000Velocity [km/s]

−0.15

−0.10

−0.05

0.00

τ

27

χ2 = 1.42

Figure 5.2: (b) - H I profiles (11 detections) in the intermediate width region at 100km s−1< FWHM < 200 km s−1.


−1000 −500 0 500 1000Velocity [km/s]

−0.07

−0.06

−0.05

−0.04

−0.03

−0.02

−0.01

0.00

τ7

χ2 = 3.6

−1000 −500 0 500 1000Velocity [km/s]

−0.04

−0.03

−0.02

−0.01

0.00

0.01

0.02

0.03

τ

11

χ2 = 1.21

−1000 −500 0 500 1000Velocity [km/s]

−0.0015

−0.0010

−0.0005

0.0000

0.0005

0.0010

τ

15

χ2 = 1.18

−1000 −500 0 500 1000Velocity [km/s]

−0.015

−0.010

−0.005

0.000

0.005

0.010

0.015

τ

17

χ2 = 0.91

−1000 −500 0 500 1000Velocity [km/s]

−0.15

−0.10

−0.05

0.00

τ

19

χ2 = 1.97

−1000 −500 0 500 1000Velocity [km/s]

−0.08

−0.06

−0.04

−0.02

0.00

τ

22

χ2 = 1.45

−1000 −500 0 500 1000Velocity [km/s]

−0.010

−0.005

0.000

0.005

0.010

τ

25

χ2 = 0.8

−1000 −500 0 500 1000Velocity [km/s]

−0.005

−0.004

−0.003

−0.002

−0.001

0.000

0.001

τ

26

χ2 = 0.78

−1000 −500 0 500 1000Velocity [km/s]

−0.06

−0.04

−0.02

0.00

0.02

0.04

0.06

τ

28

χ2 = 1.0

−1000 −500 0 500 1000Velocity [km/s]

−0.010

−0.005

0.000

0.005

τ

29

χ2 = 0.77

−1000 −500 0 500 1000Velocity [km/s]

−0.14

−0.12

−0.10

−0.08

−0.06

−0.04

−0.02

0.00

τ

31

χ2 = 1.56

Figure 5.2: (c) - H I profiles (11 detections) in the broad width region at FWHM > 200km s−1.

5.3: Results 87

fit single and double peaked profiles, while with Gaussian fitting more functions areneeded for the fitting of multiple lines. Hence, using the busy function it is possibleto derive the characteristics of very different lines in a uniform way, without any pre-defined assumptions on the number of gas components that may produce the line profile.Westmeier et al. (2014) applied the busy function fit to integrated emission lines of theHI Parkes All Sky Survey (HIPASS) sample, but such a method has never been appliedto absorption lines before. We used the C++ code provided by (Westmeier et al. 2014)to fit our absorption profiles and estimate the width, asymmetry and blue/red-shift ofthe profiles. On average, the chi-square test on the fitted lines is χ2 ∼ 1.1, and thefit is successful in parametrizing 30 out of 32 profiles of our sample. The BF fails tofit the profiles in source #20, where two lines are separated in velocity, and source #4,where both emission and absorption is present in the spectra. For #4 we extract a newspectrum from the cube at a location still close to the nuclear region, where the emissionis not very strong. This spectrum can be successfully fitted by the BF. For source #20,we evaluate the profile parameters of the main (stronger) component using Gaussianfitting.

The FWHM and the Full Width at 20% Maximum (FW20) of the lines are estimatedby measuring the width of the fitted busy function profiles at 50% and at 20% of thepeak intensity. The line centroid is measured at the middle point of the width at 20%.These parameters are summarized in Table 5.1 for all the absorption lines of our sample.

5.3.2 Characterization of the profiles with BF parametersThe profile width distribution of our sample is presented in Fig. 5.3. The sample ofgas-rich mergers and blue (g − r < 0.7) objects, which were excluded from Chapter4, are marked by yellow squares. We detect a broad range of widths between 32 kms−1 < FWHM < 570 km s−1 and 63 km s−1 < FW20 < 825 km s−1. Following avisual inspection we find that broader profiles are more complex than narrow lines. Weclearly see a separation in shape with increasing width, it appears that we can separatethree groups, representing physically different H I structures. The first group consistsof narrow single components, the second group of two (or more) blended components,whereas profiles in the third group include well separated double components. Thesegroups are presented and separated at the dashed lines in Fig. 5.3. The grouping of theH I profiles in Fig. 5.2 is also based on this selection. This separation is further supportedby the asymmetry analysis below.

In order to quantify the asymmetry of the detected lines, we derive the asymmetryparameter as the ∆vCP = vCentroid - vHI Peak velocity offset between the centroid andthe peak intensity of the H I line. In Fig. 5.4 (top panel) we show the absolute valueof the asymmetry distribution as function of the FW20 profile width. We find that innarrow profiles at FW20 < 200 km s−1, the offset between the centroid and the H I peakis < 50 km s−1. In the group with 200 km s−1 < FW20 < 300 km s−1, the asymmetryparameters are larger, with up to 100 km s−1 difference between the line centroid and theH I peak. Broad detections at FW20 > 300 km s−1 have the most asymmetric profiles,with |∆vCP| parameters larger than a few × 100 km s−1. Thus, the grouping of objects inFig. 5.3 is further supported by the increasing asymmetry observed in the three groups,and this grouping will be used in the further analysis.

Among broad lines with FW20 > 300 km s−1 there are almost no symmetric pro-


0 100 200 300 400 500 600 700 FWHM (km/s)

0

200

400

600

800

1000 FW20 (km

/s)

1:1ExtendedMergers+BlueCompact

Figure 5.3: The FWHM and FW20 width distribution of the 32 detections derived withthe busy function

files detected in Fig. 5.4 (top panel). Narrow lines cannot yield large asymmetries byconstruction, hence we normalize the asymmetries by the FW20 of the lines in Fig. 5.4(bottom panel), obtaining a more uniform distribution. Nevertheless, we confirm thetrend that symmetric broad lines (with FW20 > 300km s−1) are missing.

To expand on the analysis of the line asymmetries, we derive the velocity offset ofthe H I peak (with respect to the systemic velocity) to quantify the blueshift/redshiftdistribution of the main, deepest H I component. In Fig. 5.5 no clear correlation is seenbetween the velocity offset and the width distribution of the lines. A detection is classi-fied as blueshifted/redshifted if the velocity offset of the line is larger than ± 100 km s−1.

Using the line parameters presented above of the three width regions (introduced inFig. 5.3), we aim to identify H I structures belonging to different morphological groups:disks, clouds in radial motion (outflows, in fall), and other unsettled gas structures, forexample gas-rich mergers.1 In general, narrow lines of a few × 100 km s−1 at the systemicvelocity can be due to gas regularly rotating in a disk-like structure, e.g. high resolutionobservations show that the main (deep) absorption component in 3C 293 is associatedwith an H I disk (Beswick et al. 2004). However, the origin of H I profiles with broaderwidth of the order of > 500 km s−1 has to involve other physical processes, e.g. disturbedkinematics due to mergers, outflows, in order to accelerate the gas to such high velocities.We expect to find H I disks in the narrow region, while broader, asymmetric profiles, forexample outflows must belong to the broadest group with large FW20 in our sample.The nature of the gas structures in the three groups is discussed in Sec. 5.4.

1 Following what has been found by the detailed (and spatially resolved) studies of single objects

5.3: Results 89

Figure 5.4: 1. (Top panel): asymmetry vs. FW20 distribution of the 32 detections.2. (Bottom panel): Normalized asymmetry parameter vs. FW20 width distribution.The classification of the groups is based on the width regions from Fig. 5.3. Blackdiamonds mark narrow lines with FWHM < 100 km s−1, black crosses mark the middlewidth region with 100 km s−1< FWHM < 200 km s−1, empty circles indicate broadline detections with FWHM > 200 km s−1, and yellow squares indicate blue (g − r <0.7) objects and mergers, which objects were excluded from our discussion in Chapter4. In the histograms grey bars mark narrow lines, the crossed hatched region indicatesintermediate width profiles, the dotted hatched region marks broad lines, whereas yellowbars mark mergers and blue objects.


Table 5.1: Busy fit parameters of the H I absorption lines. The horizontal lines separatethe three groups from Fig. 5.2 (a), (b), (c).

Source ID FWHM FW20 Centroid vHI Peak(km s−1) (km s−1) (km s−1) (km s−1)

# 3 82 ± 24 108 ± 26 -243 -209# 4 80 ± 13 135 ± 13 44 78# 5 79 ± 37 127 ± 20 58 89# 10 62 ± 1 96 ± 4 -108 -83# 12 90 ± 9 122 ± 10 18 25# 13 32 ± 1 69 ± 1 34 80# 16 60 ± 10 141 ± 14 356 406# 21 43 ± 6 63 ± 7 -23 19# 30 47 ± 3 72 ± 3 -16 4#32 77 ± 11 115 ± 12 -21 2# 1 122 ± 15 245 ± 16 -22 -20#2 190 ± 9 266 ± 10 104 54#6 119 ± 6 182 ± 6 -39 -34#8 125 ± 4 179 ± 11 -67 -12#9 156 ± 15 190 ± 21 -58 -51#14 146 ± 7 175 ± 9 -50 -81#18 134 ± 294 245 ± 176 59 148#20 138 ± 53 211 ± 80 -134 -134#23 100 ± 1 231 ± 1 -142 -71#24 180 ± 14 275 ± 23 -196 -171#27 101 ± 15 161 ± 54 18 33#7 536 ± 10 825 ± 11 -78 26#11 175 ± 38 301 ± 50 -148 -183#15 370 ± 152 586 ± 72 -285 -114#17 172 ± 42 584 ± 85 -309 -132#19 272 ± 4 416 ± 5 27 28#22 570 ± 2 638 ± 2 85 -95#25 286 ± 56 422 ± 53 -67 -196#26 162 ± 10 461 ± 91 20 139#28 232 ± 32 360 ± 38 -29 -19#29 464 ± 30 674 ± 22 -256 -26#31 358 ± 34 500 ± 7 -36 -149

5.4: The nature of H I absorption in flux-selected radio galaxies 91

5.4 The nature of H I absorption in flux-selected radiogalaxies

Using stacking techniques, in Chapter 4 we show that in some of our galaxies H I mustbe distributed in a flattened (disk) morphology, whereas H I has a more unsettled distri-bution in other galaxies of our sample. This is in good agreement with the ATLAS3D

study (Serra et al. 2012) of field early-type galaxies (ETGs). ATLAS3D has shown thatroughly half of the H I detections in ETGs are distributed in a disk/ring morphology,and H I has an unsettled morphology in the other half of the detected cases.

Here, our main goal is to use the BF parameters to identify such disks and unsettledstructures. As mentioned in Sec. 5.3.2, based on the different shapes of the profiles weexpect to find different morphological structures in the three groups separated by thedashed lines in Fig. 5.3.

In Fig. 5.5, 80% of the narrow lines with FWHM < 100 km s−1 are detected closeto the systemic velocity with vHI Peak < ± 100 km s−1. Narrow profiles at the systemicvelocity are most likely produced by large scale disks, as seen in the case of the ATLAS3D

sample of early-type galaxies, where typical FWHM < 80 km s−1 have been found for theH I absorption lines. Previously, H I disks with similar profile characteristics have beenobserved in radio galaxies, e.g. in Cygnus A (Conway 1999; Struve et al. 2010), HydraA (Dwarakanath et al. 1995). Besides disks at the systemic velocity, for narrow lineswe also see one case where the H I peak is redshifted by +406 km s−1 (in source #16).Such narrow lines can be produced by infalling gas clouds with low velocity dispersion.Similar cases of highly redshifted lines have been detected before, e.g. in NGC 315 thenarrow absorption is redshifted by +500 km s−1. Morganti et al. (2009) found that theredshifted H I line in NGC 315 is produced by a gas cloud at a few kpc distance from thenucleus. In 4C 31.04, a neutral hydrogen cloud is detected with 400 km s−1 projectedvelocity towards the host galaxy (Mirabel 1990), whereas in Perseus A the H I absorptionis redshifted by ∼3000 km s−1 (van Gorkom & Ekers 1983; De Young et al. 1973), andits nature is still unclear.

For intermediate widths in Fig. 5.3, H I is still detected close to the systemic ve-locity in most (73%) of the cases, while 27% of the lines are blueshifted/redshifted (2blueshifted, 1 redshifted). In Fig. 5.2 (b) we see that multiple H I components of un-settled gas make the H I kinematics more complex in this group. These are indicationsthat relatively large widths of 100 km s−1 < FWHM < 200 km s−1 can be producedby similar gas structures as narrow detections (disks, clouds), but with more complexkinematics.

Among the broadest lines with FWHM > 200 km s−1, the main H I component isblueshifted/redshifted in 55% of the cases (5 blueshifted and 1 redshifted source). Asmentioned earlier in Sec. 5.3.2, in Fig. 5.4 there are no symmetric lines detected atFW20 > 300 km s−1. The combination of broad widths and lack of symmetry couldsuggest that indeed these profiles are the result of unsettled gas.

Indeed, for these widths we find blueshifted, broad wings, e.g. in 3C 305, where boththe kinematical and spatial properties of the H I indicate the presence of fast, jet-drivenoutflows (Morganti et al. 2005). In fact, when broad and blueshifted wings occur, thecentroid velocity is a better measure of the line offset than the H I peak (with respectto the systemic velocity). To test any connection of the radio power with the H I gasmotions in our sample, in Fig. 5.6 we plot the velocity offset of the H I centroid against


the radio power of the AGN. Below, in Sec. 5.4.1 we discuss the gas and radio sourceproperties of such blueshifted, broad lines.

In the broadest group we find three cases with very broad, multi-peaked H I profiles.In the SDSS images these galaxies are gas-rich mergers and we discuss the nature of theseobjects in Sec. 5.4.3. Despite not being a merger, #31 also has a very broad H I profilewith multiple peaks. In fact, source #31 is an early-type galaxy in the Abell cluster. Thebroad and multi-peaked nature of the profile of #31 is indicative of complex gas motionswithin the galaxy cluster. H I in absorption in clusters has been detected before in Abell2597 (O’Dea et al. 1994; Taylor et al. 1999) and in Abell 1795 (van Bemmel et al. 2012).

5.4.1 Are powerful AGN interacting with their ambient gaseousmedium?

In our sample, we find that the detection rate of blueshifted (vCentroid - vSystemic < -100 km s−1) absorption is relatively high, 29% (9 sources) in Fig. 5.6, whereas a lowerfraction, 6% (2 sources) of the detections are redshifted (vCentroid - vSystemic > +100 kms−1). The blueshift/redshift distribution of H I absorption lines was previously studiedby Vermeulen et al. (2003), who found a similar trend in a sample of GPS and CSS

Figure 5.5: Blueshift/redshift distribution of the H I peak with respect to the systemicvelocity vs. the FWHM of the 32 detected lines. The symbols are the same as in Fig.5.4


Figure 5.6: Blueshift/redshift distribution of the H I line centroid with respect to thesystemic velocity vs. the radio power in the sample of 32 detections. The symbols arethe same as in Fig. 5.4

sources. In the sample of Vermeulen et al. (2003), 37% of the profiles are blueshifted,and 16% are redshifted with respect to the systemic velocity. A later study confirmed thistrend, Gupta et al. (2006) reported a high, 65% detection rate of blueshifted H I profilesin GPS sources. These studies speculate that interactions between the radio source andthe surrounding gaseous medium is the cause of the outflowing gas motions in higherluminosity sources.

The three most blueshifted (vCentroid - vSystemic < -250 km s−1) profiles in Fig. 5.6are broad lines with FW20 > 500 km s−1. By number identifier these are #15, #17 and#29. These detections show similar kinematical properties as the outflows in 3C 293 and3C 305 by displaying broad wings of blueshifted absorption.

The H I outflows in 3C 305 and 3C 293 are driven by powerful radio sources withlog(P1.4 GHz) > 25 W Hz−1 (see Table 5.0). It was estimated that in 3C 305 and 3C293, the kinetic energy output of the jets is high enough to accelerate the gas to highvelocities of about 1000 km s−1 (Morganti et al. 2003, 2005; Mahony et al. 2013). InFig. 5.6 it appears that blueshifted, broad detections in our sample (in #15, #17 and#29) are likely to occur in high power radio galaxies with log(P1.4 GHz) > 25 W Hz−1,suggesting that their energy output is similar to that of 3C 305 and 3C 293. These areindications that interactions with the powerful radio source may be driving H I outflows


Figure 5.7: Blueshift/redshift vs. FWHM distribution of the H I peak with respectto the systemic velocity in compact and extended sources. Yellow squares indicate blue(g − r < 0.7) objects and mergers, as in the previous figures.

in these sources, and we discuss this possibility in more detail in Sec. 5.4.2.Even though the velocity offset of H I lines can be due to infalling/ouflowing gas,

we should not rule out the possibility that in some cases we may be looking at theline-of-sight rotational motion of the gas (Morganti et al. 2001; Vermeulen et al. 2003).

5.4.2 Fraction and time-scale of candidate H I outflowsRadio AGN are thought to be able to drive fast gas outflows through jet-cloud interac-tions. Because such H I outflows are very faint, with typical optical depth of τ = 0.01,until now only a handful of confirmed H I outflows are known (Morganti et al. 1998,2003, 2005, 2013). Besides 3C 305 (also detected here) and 3C 293 (where the broad,blueshifted component is only barely detected here, and not fitted by the BF for lack ofsensitivity), in our sample we have three other cases, where in addition to the main H Icomponent (deep H I detection close to the systemic velocity) a blueshifted shallow wingis seen.

Source 4C +52.37 (source #29) is a CSS source from the CORALZ sample (see morein Sec. 5.5), and we find a broad blueshifted wing in this galaxy with FW20 = 674km s−1 (see Table 5.1). The dataset of the first set of observations of this source ishighly affected by RFI. Thus, in order to verify our detection, we carried out follow-up


Figure 5.8: 1. (Top panel): Asymmetry parameter vs. FW20 distribution of com-pact (red circles) and extended (blue squares) sources. 2. (Bottom panel) Normalizedasymmetry parameter vs. FW20 width distribution of the same groups. Yellow squaresindicate blue (g − r < 0.7) objects and mergers, as in the previous figures. In thehistograms compact sources are marked by red bars, the blue hatched region indicatesextended sources, and yellow bars indicate mergers and blue objects.


observations of 4C +52.37, and confirm the presence of the wing by the second set ofobservations. Source #15 and #17 share similar kinematical properties, showing broadlines of almost ∼590 km s−1 FWHM. Even though in #15 the main, deeper componentis not as prominent as in other two cases, Saikia & Gupta (2003) detected higher degreeof polarization asymmetry in this object (4C +49.25). Saikia & Gupta (2003) argue thatsuch polarization properties can indicate interactions of the radio source with clouds ofgas which possibly fuel the AGN.

Based on their H I kinematical and radio source properties (see Sec. 5.4.1), we considerthese sources the best candidates for hosting jet-driven H I outflows. However, moresensitive and higher resolution observations are needed to verify that these detectionsare indeed jet-driven, and to estimate how much of the energy output is concentratedin the jets. Including the two already known outflows in 3C 305, 3C 293, in our flux-selected sample the detection rate of outflows at the sensitivity of our observations is∼15% among detections, or 5% in all observed radio sources.

Considering the 5% detection rate and the typical lifetime of radio sources (between107 - 108 yr, Parma et al. 1999, 2007), if every radio source goes through a phase ofoutflow, it means that H I outflows last (on average) not more than a few Myr. Thus, theoutflow would appear as a relatively short phase in the life of the galaxy. This is similarto that which is derived from observations of the molecular gas. Using CO observations,Cicone et al. (2014) estimated a gas depletion time of a few million years in a sampleof galaxies hosting powerful AGN. In the case of NGC 1266 from the ATLAS3D sample(Alatalo et al. 2011), the mass outflow rate is 13 M⊙ yr−1, and if the gas in the nucleusis the source of the molecular outflow, the estimated depletion time scale is < 85 Myr.

5.4.3 Gas rich mergers

Among our detections we find three cases of broad (with FW20 of 416 km s−1, 638 kms−1 and 825 km s−1 in increasing order), multi-peaked profiles in UGC 8387, Mrk 273and UGC 05101. The host galaxies of these broad H I detections are gas-rich mergingsystems. In these sources, a combination of AGN and enhanced star-forming regions islikely to be the origin of the radio emission.

In Table 5.0, gas-rich mergers have the highest column densities in the range (5 -8) × 1019 (Tspin/cf) cm−2, reflecting extreme physical conditions of the gas in merginggalaxies. Even though the presence of AGN is not always clear in merging systems, thereexist tentative signs that the presence of gas has an effect on the growth of mergingBHs. Very Long Baseline Array (VLBA) observations of the H I absorption in Mrk 273by Carilli & Taylor (2000) show that the broad H I profile is the result of several co-added components in this source (see notes on individual sources in Appendix 5.8.1).In particular, Carilli & Taylor (2000) detected an infalling gas cloud towards the South-Eastern component (SE) of Mrk 273, indicative of BH feeding processes. Consideringthe broad and multi-peaked nature of the H I in UGC 8387 and UGC 05101, thesesources likely have similar gas properties to Mrk 273, e.g. H I absorption originatingfrom several unsettled components. With our low-resolution observations we can notdistinguish between the different absorbing regions in merging systems, therefore wedetect the blended, broad H I signal.

5.5: The H I properties of compact and extended sources 97

Figure 5.9: Blueshift/redshift distribution of the H I line centroid vs. the radio powerof compact (red circles) and extended sources (blue squares). Yellow squares indicateblue (g − r < 0.7) objectsmergers.

5.5 The H I properties of compact and extended sourcesIn Chapter 4 we found that compact sources have higher τ , FWHM and column densitythan extended sources. Here, using the BF parameters we expand on these results byexamining in more detail the difference in the H I properties of the two types of radiosources. In the following analysis we focus on the sample of 27 red (g−r < 0.7) detections.

In Fig. 5.7 and Fig. 5.8 we present the width distribution of compact and extendeddetections. As expected from the stacking results, the busy function analysis shows thatcompact sources tend to have broader lines. In Chapter 4 we suggested that the largerwidth in compact sources is due to the presence of unsettled gas. In Sec. 5.4 we show thatunsettled gas is typically traced by asymmetric lines, furthermore redshifted/blueshiftedlines can also indicate non-rotational gas motions.

In Fig. 5.8, among broad lines with FW20 > 300 km s−1, a high fraction, 88% of thesources, is compact (7 out of 8), while only one source is extended (17%). As mentionedearlier in Sec. 5.4, the lack of symmetric lines suggests that such broad profiles arisedue to non-rotational gas motions of unsettled gas. The largest asymmetry of |∆vCP|∼ 250 km s−1 is measured in the compact source 4C +52.37, one of our H I outflowcandidates. Furthermore, in Fig. 5.7, almost 90% (7 sources out of 8) of blueshifteddetections with vHI Peak < -100 km s−1 are compact sources, whereas only one source


10-3 10-2 10-1 100 101

Linear size (kpc)

1017

1018

1019

1020N(HI) · c f / T

spin [cm

−2 K

−1]

CORALZ non-detectionsCORALZ detections

Figure 5.10: Radio source size vs. column density in GPS and CSS sources from theCORALZ sample

(∼10%) is extended.Fig. 5.8 and Fig. 5.7 show that the traces of unsettled gas, e.g. blueshifted and

broad/asymmetric lines, are found more often among compact sources. This suggests alink between the morphology of the radio source and the kinematics of the surroundinggas. In fact, all three H I outflow candidates (#15, #17 and #29) from Sec. 5.4.2 areclassified as compact in Fig. 5.9 and Table 5.0. Hence, the presence of unsettled gassuggest that interactions between small (< 10 kpc) radio sources and the rich ambientmedium are likely to occur in the young, compact phase of AGN, providing favourablesites for powerful jet-cloud interactions.

As we mention in Chapter 4, nine of our AGN are part of the COmpact RAdiosources at Low redshift (CORALZ) sample (Snellen et al. 2004; de Vries et al. 2009),a collection of young CSS and GPS sources. The de Vries et al. (2009) observationsprovided high resolution MERLIN, EVN and global VLBI observations of the CORALZsample at frequencies between 1.4 - 5 GHz, along with radio morphological classificationand source size measurements.

Previously, H I observations of 18 CORALZ sources were obtained by Chandola et al.(2010), yielding a 40% H I detection rate. Our sample includes fewer, 11 objects, and wefind a 55% detection rate. We observed three CORALZ sources which were not studiedby Chandola et al. (2010). Among the three sources we have two new detections: #20,#21 and one non-detection: #52.

Pihlström et al. (2003); Gupta et al. (2006); Chandola et al. (2010) reported a col-umn density vs. radio source size anti-correlation for CSS and GPS sources, accountedfor the fact that at larger distances from the nucleus, lower opacity gas is probed in frontof the continuum (Fanti et al. 1995; Pihlström et al. 2003). More recently, Curran et al.(2013) pointed out that the N(H I)-radio size inverse correlation is driven by the fact that

5.6: Summary 99

the optical depth is anti-correlated with the linear extent of the radio source. In Fig. 5.10we plot the largest projected linear size (LLS) of the sources reported by de Vries et al.(2009) against the column densities measured from our H I profiles. The column densityof the detections decreases as function of radio source size. However, adding the N(H I)upper limit makes the trend much less clear. In fact, high frequency peakers (HFPs) werealso found not to be following the inverse correlation (Orienti et al. 2006). HFP galaxiesare thought to be recently triggered, 103-105 yr old, small radio sources of a few tens ofpc. Orienti et al. (2006) measured low column densities in these tiny sources, and theyexplain the low column density of HFPs by a combination of orientation effects and thesmall size of the sources. In this scenario, our line-of-sight intersects the inner region ofthe torus against the tiny radio source, therefore in absorption we can only detect thishigh Tspin, (and therefore) low column density gas close to the nucleus.

The above results suggest that both orientation effects and the radio source size canbe affecting the measured optical depths, and the combination of these effects may beresponsible for deviations from the N(H I) to radio size inverse correlation also in oursample in Fig. 5.10.

5.6 SummaryIn this paper we presented the results of an H I absorption study of a sample of 101AGN. The relatively large sample of 32 detections has been parametrized using the busyfunction (Westmeier et al. 2014). The total sample was selected and used for stackingpurposes in Chapter 4, and here we carry out a detailed analysis of the individual profiles.Detections in our sample display a broad range of line shapes and kinematics. The busyfunction is efficient in fitting almost all of the spectra, except for a few peculiar caseswith multiple lines and H I emission features.

In Chapter 4 we find that H I disks and unsettled gas structures are both present inour sample. Here we attempt to disentangle different H I morphological structures usingthe busy function parameters. We find that the complexity of the lines is increasing withincreasing profile width. Based on the line shapes we separate three groups of objectswith different kinematical properties. The narrowest lines with FWHM < 100 km s−1 inour sample are most likely produced by large scale disks or H I clouds. Relatively broadlines (100 km s−1 < FWHM < 200 km s−1) may be produced by similar morphologicalstructures with more complex kinematics. Broad lines with FWHM > 200 km s−1,however, are tracing the most unsettled gas structures, e.g. gas-rich mergers and outflows.

We detect three new cases with broad, blueshifted H I wings. Along with their radiosource properties, i.e. powerful AGN with log(P) > 25 W Hz−1, these sources are thebest candidates for being jet-driven H I outflows. Considering certain and tentative cases,the detection rate of H I outflows is 5% in our total sample. If all radio AGN go throughan outflow phase during their lifetime, the relatively low detection rate suggests thatthe gas depletion timescale of H I outflows is shorter than the typical lifetime of radiogalaxies.

In Chapter 4 we show that the stacked profile of compact sources is broader than thestacked width of extended sources. Here we confirm this result using the BF parametersof the individual detections. H I in compact sources often shows the characteristics ofunsettled gas, e.g. blueshifted lines and broad/asymmetric profiles. Such H I line proper-ties suggest that strong interactions between AGN and their rich circumnuclear medium


are likely to occur in compact AGN, as young radio jets are clearing their way throughthe ambient medium in the early phases of the nuclear activity.

5.7 AcknowledgementsThe WSRT is operated by the ASTRON (Netherlands Foundation for Research in As-tronomy) with support from the Netherlands Foundation for Scientific Research (NWO).We thank Tobias Westmeier and Russell Jurek for the useful suggestions on the busy func-tion fitting module. RM gratefully acknowledges support from the European ResearchCouncil under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Advanced Grant RADIOLIFE-320745.

5.8: Appendix 101

5.8 Appendix5.8.1 Notes on the individual detections#1: B3 0754+401This source is part of the low luminosity CSS sample presented by Kunert-Bajraszewska& Labiano (2010). The largest linear size of the source is 0.25 kpc, and the morphologyremains unresolved in the multi-element radio linked interferometer network (MERLIN)observations. Kunert-Bajraszewska & Labiano (2010) classified this object as a High Ex-citation Galaxy (HEG). We detect H I in this source at the systemic velocity. The widthand asymmetry parameters of the H I suggest that the gas in this galaxy is not entirelysettled.#2: 2MASX J08060148+1906142This source has not been studied individually before. The relatively large width (FW20= 266km s−1) and double-peaked nature of the H I profile suggests that unsettled gas ispresent in this galaxy.#3: B2 0806+35This source shows radio emission both on the kpc and pc scale. It has been observed withVLBA at 5 GHz as part of a polarization survey of BL-Lac objects (Bondi et al. 2004)as a possible BL-Lac candidate. On the parsec scale (beam size of 3.2 × 1.7) the sourcereveals a radio core with an extended jet towards the south. The jet extends for about10 milliarcseconds (mas) (∼ 15 pc at z = −0.0825). Among the BL-Lac candidates, thissource is the weakest object, and has the steepest radio spectrum. It is also the onlyobject not showing polarized emission neither in the jet or the core. In this galaxy, thenarrow H I line is detected at blueshifted velocities with respect to the systemic.#4: B3 0833+442In the CORALZ sample this source is classified as a CSO. However the 1.6 GHz VLBIimage (de Vries et al. 2009) shows a C-shaped radio structure. The LLS of the source is1.7 kpc. Chandola et al. (2010) did not find H I in this source. In our observations, wedetect a narrow H I profile, slightly redshifted from the systemic velocity. The data cubealso reveals (faint) H I emission.#5: B3 0839+458This source has been observed as part of the CRATES sample (Healey et al. 2007). Ithas been classified as a point source with flat spectrum (spectral index α = −0.396). TheVLBA observations at 5 GHz, as part of the VISP survey (Helmboldt et al. 2007), classifyit as a core-jet source. The lobes have sizes of approximately 3.5 mas and are separatedby 6 mas (= 0.2 kpc at z = 0.1919). The radio power of the source is P1.4GHz ∼ 3·1025 WHz−1. In our work, we detect the H I at the systemic velocity of the galaxy (∆v = 57 kms−1). The line is narrow and deep, suggesting that the H I is settled in a rotating diskaround the host galaxy. The line has a slight asymmetry along the blue-shifted edge notfitted by the busy function.#6: Mrk 1226This source has been observed as part of the CRATES sample (Healey et al. 2007). Ithas been classified as a point source with flat spectrum (spectral index α = 0.284). Theobject has also been observed as part of the VISP survey at 5 GHz (Helmboldt et al.2007). The approximate size of the radio source is 15 mas (∼ 8 pc at z = 0.0279). Wedetect H I absorption close to the systemic velocity of the host galaxy. This, along withthe symmetry of the line, suggests that we are tracing neutral hydrogen rotating in a


disk. The host galaxy may have experienced a gas rich merger which has formed the H Idisk.#7: UGC 05101 - IRAS F09320+6134This radio source is hosted by an Ultra-Luminous far-IR Galaxy. The galaxy is under-going a merger event, as also suggested by its optical morphology. The source has alsobeen observed with a ∼ 11.6 × 9.9 mas resolution using VLBI (Lonsdale et al. 2003).These observations show three compact (. 3−4 pc) cores connected by a fainter compo-nent. The size of the overall structure is 48 × 24 pc. These VLBI observations also showthat the radio continuum is dominated by the AGN and not by the starburst activity.The radio power of the source is P1.4GHz ∼ 3 · 1023 W Hz−1. At the resolution of ourobservations, we are not able to disentangle the absorption seen against the differentcomponents: we detect a broad, blended line. The profile is also multi-peaked, reflectingthe unsettled state of the neutral hydrogen disk and of the overall host galaxy. The H Ihas been detected in emission via Effelsberg Telescope observations, through the studyof Polar-Ring Galaxy candidates (Huchtmeier 1997). The emission line is broad andasymmetric, with a peak flux of +2.2 mJy beam−1. The low sensitivity of the spectrumdoes not allow to set further constraints. The H I emission detection has been confirmedby observations with the Nançay decimetric radio telescope, with have higher sensitivity(van Driel et al. 2000).2#8: 4C +48.29This extended AGN is an X-shaped radio source (Jaegers 1987; Mezcua et al. 2011;Landt et al. 2010). We detect a double peaked H I profile close to the systemic velocity.Before Hanning smoothing, the two peaks are more separated, suggesting the presenceof two H I components (one at the systemic and one blueshifted).#9: J105327+205835In the literature there are no records of individual observations of this radio source. TheNVSS and FIRST images suggest that it is a compact source. In our observations, wedetect a broad profile peaked at the systemic velocity and slightly asymmetric towardsblue-shifted velocities. The SDSS image shows that the host galaxy of this source is veryclose to a companion. Past interaction with a companion could explain the presence ofthe H I in the system.#10: 2MASX J112030+273610There are no individual radio observation of this source reported in the literature. Ac-cording to our classification, it is a compact source. The detected H I profile is narrowand blue-shifted with respect of the optical velocity. This may indicate that we are trac-ing neutral hydrogen which is not settled in a rotating disk.#11: 2MASX J12023112+1637414This source has never been studied individually before. According to our classification itis a compact source, showing a shallow, blueshifted profile, indicative of outflowing gas.#12: NGC 4093 - MCG +04-29-02VLA observations reveal compact radio morphology in this source (Burns et al. 1987;del Castillo et al. 1988). We detect a regular H I component at the systemic velocity,likely tracing the kinematics of a rotating disk.#13: B3 1206+469This radio source has been selected as part of the CLASS survey as a possible BL-Lacobject and then classified as a lobe dominated steep spectrum source. This radio source2 The galaxy belongs to the HYPERLEDA catalogue Paturel et al. (2003)

5.8: Appendix 103

is extended with a central core and two symmetric lobes oriented in the north-south di-rection. The distance between the lobes is ∼ 4 arcminutes (∼ 550 kpc at z = 0.100). Thespectral index has been measured in the wavelength intervals 1.4 − 4.8 GHz and 1.4 − 8GHz: α4.8

1.4 = 0.04, α81.4 = 0.39; (Marchã et al. 2001). Being extended, the steepness of

the spectrum may be explained by the fact that some of the flux is missed by the VLAobservations at 8.4 GHz. In our observations we detect a narrow and shallow absorptionline close to the systemic velocity.#14: B2 1229+33This extended source was classified as an FR II by Cohen et al. (2004). Based on theSDSS optical spectrum and image, it is a High Excitation Radio Galaxy (HERG). TheH I profile shows a narrow detection at the systemic velocity. Furthermore, a second,redshifted component is also seen. These H I properties suggest the presence of a diskand infalling gas in this object.#15: 4C +49.25The size of this CSS source is 6 kpc (Saikia & Gupta 2003; Fanti et al. 2000). The 5 GHzVLA map reveals a core and two jets on the opposite sides (Saikia & Gupta 2003). Itwas suggested by Saikia & Gupta (2003) that the higher degree of polarization asymme-try in CSS objects, including 4C +49.25, could be the result of interactions with cloudsof gas which possibly fuel the radio source. Indeed, we find a blueshifted, shallow H Icomponent in this source. This could be the result of outflowing gas, induced by jet-ISMinteractions. At the systemic velocity, however, we do not detect H I.#16: 2MASX J125433+185602The source belongs to the Combined Radio All-Sky Targeted Eight GHz Survey (CRATES)sample (Healey et al. 2007). It has been classified as a point source with flat spectrum(spectral index α = 0.282). Observations at 5 GHz, as part of the VLBA Imaging andPolarimetry survey (VISP, Helmboldt et al. 2007), identify this source as a CSO. Itslobes are separated by 7.3 mas (∼ 15 pc at z ∼ 0.0115). We detect H I at redshiftedvelocities compared to the systemic. The line is narrow and asymmetric, with a broaderwing towards lower velocities. The redshift of the line, along with the compactness ofthe source, suggests that the neutral hydrogen may have motions different from simplerotation in a disk.#17: 2MASX J13013264+4634032According to Augusto et al. (2006), this radio source is a point source. We detect afaint, blueshifted H I profile, which can indicate interactions between the AGN and thesurrounding gaseous medium. The radio source is a Blazar candidate in the CosmicLens All Sky Survey (CLASS) and Combined Radio All-Sky Targeted Eight GHz Sur-vey (CRATES) surveys (Caccianiga et al. 2002; Healey et al. 2007). However, it remainsclassified as an AGN by Caccianiga et al. (2002).#18: B3 1315+415VLBI observations of the CORALZ sample (de Vries et al. 2009) reveal complex radiomorphology in this object. The source has a small size of LLS = 5 pc. From the lobeexpansion speed analysis (de Vries et al. 2010), a dynamical age of 130 yr is estimatedin this source. Chandola et al. (2010) detected H I absorption redshifted by +77 km s−1

relative to the systemic velocity, indicating in-falling gas towards the nuclear region. Ourobservations confirm the H I detection.#19: IC 883 - ARP 193 - UGC 8387The host galaxy of this radio source is undergoing a major merger. The galaxy is a Lumi-


nous far Infra-Red Galaxy (LIRG) where LIR = 4.7·1011L⊙ at z = 0.0233 (Sanders et al.2003). The radio source has been observed with e-Merlin (beam size = 165.23 × 88.35mas) and VLBI e-EVN (beam size = 9.20 × 6.36 mas) (Romero-Cañizales et al. 2012).The radio source consists of 4 knots and extends for about ∼ 750 pc. The innermost100 pc of the galaxy show both nuclear activity and star formation. The nuclear activityoriginates in the central core, while the radio emission from the other knots is attributedto transient sources. This galaxy has already been observed in H I in the study of PolarRing galaxy candidates (Huchtmeier 1997). Two complementary observations have beenperformed using the Green Bank Telescope and the Effelsberg Telescope. Due to thedifferent sensitivity of the instruments, the H I has been detected in emission only in theGreen Bank observations (Richter et al. 1994), with a peak flux = 2.4 mJy. In IC 883,CO(1-0) and CO(3-2) are detected by Yao et al. (2003) in the same range of velocities asthe H I emission. The resolution of our observations does not allow the disentanglementof different absorption components. Hence, the H I line in our observations is blended,spanning the same velocity range of the H I seen in emission, and of the molecular gas.The morphology of the absorption line, along with the overall properties of the cold gasdetected in emission, suggests that in this galaxy the cold gas is rotating in a disk, whichis unsettled due to the ongoing merger event.3#20: SDSS J132513.37+395553.2In the CORALZ sample this source is classified as a compact symmetric object (CSO),with largest (projected) linear size (LLS) of 14 pc (de Vries et al. 2009). Our observa-tions show two H I components, one blueshifted, and the other redshifted relative to thesystemic velocity. The newly detected H I profiles suggest that unsettled gas structuresare present in this galaxy, e.g. infalling clouds, outflowing gas.#21: IRAS F13384+4503This galaxy is optically blue (g − r = 0.6), and the SDSS image revels a Seyfert galaxywith late-type morphology. In the CORALZ sample, the radio source is classified as acompact core-jet (CJ) source with two components which are significantly different influx density and/or spectral index (de Vries et al. 2009). The largest linear size of thesource is 4.1 pc. Against the small continuum source, a very narrow H I absorption profileis detected at the systemic velocity, indicative of a gas disk.#22: Mrk 273This object is the host of an ongoing merger. The optical morphology shows a longtidal tail extending 40 kpc to the south (Iwasawa et al. 2011, and references therein).Low-resolution 8.44 GHz radio maps by Condon et al. (1991) show three radio compo-nents, a northern (N), south-western (SW), and a south-eastern (SE) region. The originof the SE and SW component is unclear (Knapen et al. 1997; Carilli & Taylor 2000).The N radio component is slightly resolved in the observations of Knapen et al. (1997);Carilli & Taylor (2000); Bondi et al. (2005), showing two peaks embedded in extendedradio emission. It is thought that the northern component is hosting a weak AGN,however it is also the site of very active star-formation. Using Very Long Baseline Ar-ray (VLBA) observations, Carilli & Taylor (2000) detected H I absorption against the Ncomponent supposedly coming from a disk (showing velocity gradient along the majoraxis), and estimated an H I gas mass of 2 × 109 M⊙. Molecular CO gas of similar amount(109 M⊙) was also detected by Downes & Solomon (1998). Carilli & Taylor (2000) alsodetect extended gas and an infalling gas cloud towards the SE component, suggesting3 The galaxy belongs to the HYPERLEDA catalogue Paturel et al. (2003)

5.8: Appendix 105

that the SE component is indeed an AGN. Our low-resolution observations can not dis-tinguish between the different absorbing regions, we detect the blended signal, comingfrom all the H I absorbing regions. The broad H I absorption was also detected with thesingle dish Green Bank Telescope (GBT) by Teng et al. (2013).#23: 3C 293This object is a Compact Steep Spectrum (CSS) radio source, divided in multiple knots(Beswick et al. 2004). It is a restarted radio source, possibly activated by a recent mergerevent (Heckman et al. 1986). Massaro et al. (2010) classify the radio source as FRI. Arotating H I disk has been detected in absorption by Baan & Haschick (1981). WSRTobservations (Morganti et al. 2005) show an extremely broad absorption component atblue-shifted velocities (FWZI = 1400km s−1). VLA-A array observations, with 1.2×1.3arcsec of spatial resolution, identify this feature as a fast H I outflow pushed by the west-ern radio jet, located at 500 pc from the core (Mahony et al. 2013). The radio jet isthought to inject energy into the ISM, driving the outflow of H I at a rate of 8 − 50 M⊙yr−1. The broad shallow outflowing component is also detected. The fit of the spectrumwith the BF identifies the rotating component, while it fails in fitting the shallow wings,highlighting the different nature of these clouds.#24: 2MASX J142210+210554There are no individual observations of this source in the literature. In our classificationscheme, the radio source is compact. The SDSS observations show that it is hosted by anearly-type galaxy. We detect an absorption line, blue-shifted with respect to the systemicvelocity. The line is broad and asymmetric with a smoother blue-shifted edge.#25: 2MASX J14352162+5051233This is an unresolved (U) CORALZ AGN, the size of the radio source is estimated tobe 270 pc. This galaxy has been observed in H I by Chandola et al. (2010), howeverno components were detected. Our observations show a shallow, broad, blueshifted H Iprofile without deep/narrow component at the systemic velocity. Likely we are seeinggas interacting with the radio source.#26: 3C 305 - IC 1065Massaro et al. (2010) classified this source as a high excitation galaxy (HEG) with FRI radio morphology. The profile shows a deep, narrow component, which could be asso-ciated to rotating gas. Furthermore, Morganti et al. (2005) reported the presence of ajet-driven H I outflow in this galaxy. The outflow is also detected in our observations, andit is successfully fitted by the BF. The column density of the outflow is N(H I) = 2 ×1021,assuming Tspin = 1000 K, and the corresponding H I mass was estimated to be M(H I) =1.3 × 107 M⊙ (Morganti et al. 2005). Molecular H II gas was also detected in this sourceby Guillard et al. (2012). However the molecular phase of the gas is inefficiently coupledto the AGN jet-driven outflow.#27: 2MASX J150034+364845In the literature, there is no record of targeted observations of this radio source. Ac-cording to our classification it is a compact source. We detect a deep absorption line(Speak

abs = −5.3 mJy beam−1). The line lies at the systemic velocity of the host galaxy andtraces a regularly rotating H I disk. The line is slightly asymmetric in the blue-shiftedrange of velocities. This asymmetry is not recovered by the BF fit, suggesting that non-circular motions characterize the neutral hydrogen.#28: 2MASX J15292250+3621423We find no individual observations of this source in the literature. In our sample it is


classified as a compact source. We detect H I in this object close to the systemic velocity.However, similarly to the case of source #9 the profile is not entirely smooth.#29: 4C +52.37This source is classified as a compact symmetric object (CSO) in the CORALZ sample.High-resolution observations reveal a core, and jet-like emission on the opposite sides(de Vries et al. 2009). The main H I absorption component in 4C +52.37 was detectedby Chandola et al. (2010), using the Giant Metrewave Radio Telescope (GMRT). Besidesthe main H I line, we detect a broad, shallow profile of blueshifted H I absorption. Thebroad component was not detected by Chandola et al. (2010), most likely because of thehigher noise of the GMRT spectra. The kinematical properties of the newly detectedblueshifted wing are indicative of a jet-driven H I outflow in this compact radio source.#30: NGC 6034This radio source is hosted by a S0 optical galaxy, which belongs to cluster A2151 of theHercules Supercluster. The radio source is extended, with two jets emerging toward thenorth and the south (Mack et al. 1993). The spectrum is flat with no variation of thespectral index (α = −0.65). The line is very narrow and it is centred at the systemicvelocity. This suggests that the H I may form a rotating disk in the host galaxy. Theneutral hydrogen in NGC 6034 has been first detected in absorption by VLA observations(Dickey 1997).4#31: Abell 2147Based on the SDSS optical images, the host galaxy of this source is an early-type galaxywith a very red bulge. Taylor et al. (2007) classified this object as a flat-spectrum radioquasar. The size of the radio source is about 10 mas (∼20 pc at z = 0.1), and themorphology remains unresolved in the 5 GHz VLBA images. Therefore, it is intriguingthat we find a broad H I detection against this very compact radio source. It is likelythat along the line of sight the H I has non-circular motions.#32: 2MASX J161217+282546The radio source is hosted by an S0 galaxy and has been observed with the VLA-A con-figuration by Feretti & Giovannini (1994). At the resolution of the VLA-A observations(1.4 × 1.1 arcseconds, ∼ 0.7 kpc at z = 0.0320), the radio source is unresolved. Wedetect an absorption line at the systemic velocity of the host galaxy, indicative of neutralhydrogen rotating in a disk.

5.8.2 Summary table of non-detections

4 the galaxy belongs to the HYPERLEDA catalogue Paturel et al. (2003)

5.8: Appendix 107In

dex

RA

,Dec

zO

ther

nam

eS 1

.4G

Hz

P 1.4

GH

zR

adio

Mor

phol

ogy

τ pea

kN

(HI)

mJy

WH

z−1

1018

(Tsp

in/c

f)cm

−2

#33

07h5

6m07

.1s

+38

d34m

01s

0.21

5605

B3

0752

+38

770

24.9

8C

<0.

041

<7.

4#

3407

h58m

28.1

s+

37d4

7m12

s0.

0408

25N

GC

2484

243

23.9

8E

<0.

009

<1.

7#

3507

h58m

47.0

s+

27d0

5m16

s0.

0987

4569

24.2

3C

<0.

056

<10

.2#

3608

h00m

42.0

s+

32d1

7m28

s0.

1872

39B

207

57+

3210

425

.01

E<

0.02

4<

4.4

#37

08h1

8m27

.3s

+28

d14m

03s

0.22

5235

4724

.84

C<

0.04

7<

8.6

#38

08h1

8m54

.1s

+22

d47m

45s

0.09

5831

194

24.6

5E

<0.

011

<2.

1#

3908

h20m

28.1

s+

48d5

3m47

s0.

1324

4712

424

.76

E<

0.02

6<

4.8

#40

08h2

9m04

.8s

+17

d54m

16s

0.08

9467

190

24.5

8E

<0.

012

<2.

1#

4108

h31m

38.8

s+

22d3

4m23

s0.

0868

8293

24.2

4E

<0.

022

<4.

0#

4208

h31m

39.8

s+

46d0

8m01

s0.

1310

6512

324

.75

C<

0.02

2<

4.1

#43

08h3

4m11

.1s

+58

d03m

21s

0.09

3357

4624

.01

C<

0.05

7<

10.4

#44

08h3

9m15

.8s

+28

d50m

47s

0.07

8961

B2

0836

+29

126

24.2

9E

<0.

023

<4.

2#

4508

h43m

59.1

s+

51d0

5m25

s0.

1263

4479

24.5

2E

<0.

041

<7.

5#

4609

h01m

05.2

s+

29d0

1m47

s0.

1940

453C

213.

116

7026

.25

E<

0.00

1<

0.3

#47

09h0

3m42

.7s

+26

d50m

20s

0.08

4306

8124

.16

C<

0.02

5<

4.5

#48

09h0

6m15

.5s

+46

d36m

19s

0.08

4697

B3

0902

+46

827

324

.69

C<

0.01

3<

2.3

#49

09h0

6m52

.8s

+41

d24m

30s

0.02

7358

5622

.99

C<

0.04

4<

8.0

#50

09h1

2m18

.3s

+48

d30m

45s

0.11

7168

143

24.7

1E

<0.

028

<5.

1#

5109

h16m

51.9

s+

52d3

8m28

s0.

1903

8563

24.8

1E

<0.

054

<9.

8#

5209

h36m

09.4

s+

33d1

3m08

s0.

0761

5261

23.9

4C

<0.

030

<5.

5#

5309

h43m

19.1

s+

36d1

4m52

s0.

0223

36N

GC

2965

104

23.0

7C

<0.

018

<3.

2#

5409

h45m

42.2

s+

57d5

7m48

s0.

2289

389

25.1

4E

<0.

030

<5.

5#

5510

h09m

35.7

s+

18d2

6m02

s0.

1164

7944

24.1

9E

<0.

088

<16

.0

Tab

le5.

2:H

Ino

n-de

tect

ions

.T

heN

(HI)

uppe

rlim

itis

calc

ulat

edfr

omth

e3-

σrm

s,as

sum

ing

100

kms−

1ve

loci

tyw

idth

.


Inde

xR

A,D

ecz

Oth

erna

me

S 1.4

GH

zP 1

.4G

Hz

Rad

ioM

orph

olog

yτ p

ea

kN

(HI)

mJy

WH

z−1

1018

(Tsp

in/c

f)cm

−2

#56

10h3

7m19

.3s

+43

d35m

15s

0.02

4679

UG

C05

771

142

23.3

C<

0.01

3<

2.4

#57

10h4

0m29

.9s

+29

d57m

58s

0.09

0938

4C+

30.1

940

724

.93

C<

0.00

7<

1.4

#58

10h4

6m09

.6s

+16

d55m

11s

0.20

6868

6324

.89

C<

0.03

9<

7.0

#59

11h0

3m05

.8s

+19

d17m

02s

0.21

4267

9925

.12

E<

0.02

4<

4.4

#60

11h1

6m22

.7s

+29

d15m

08s

0.04

5282

7323

.55

C<

0.02

5<

4.6

#61

11h2

3m49

.9s

+20

d16m

55s

0.13

0406

102

24.6

6E

<0.

035

<6.

3#

6211

h31m

42.3

s+

47d0

0m09

s0.

1257

21B

311

28+

472

100

24.6

2E

<0.

027

<4.

9#

6311

h33m

59.2

s+

49d0

3m43

s0.

0316

25IC

0708

168

23.5

9E

<0.

011

<2.

1#

6411

h45m

05.0

s+

19d3

6m23

s0.

0215

96N

GC

3862

777

23.9

2E

<0.

003

<0.

6#

6511

h47m

22.1

s+

35d0

1m08

s0.

0628

94C

GC

G18

6-04

827

624

.42

E<

0.00

6<

1.2

#66

12h0

3m03

.5s

+60

d31m

19s

0.06

5297

SBS

1200

+60

815

324

.2C

<0.

012

<2.

1#

6712

h13m

29.3

s+

50d4

4m29

0.03

0757

NG

C41

8711

023

.38

C<

0.01

9<

3.5

#68

12h2

1m21

.9s

+30

d10m

37s

0.18

3599

FBQ

SJ1

221+

3010

6024

.76

C<

0.04

4<

8.0

#69

12h2

8m23

.1s

+16

d26m

13s

0.22

9959

117

25.2

6E

<0.

023

<4.

3#

7012

h30m

11.8

s+

47d0

0m23

s0.

0390

99C

GC

G24

4-02

594

23.5

2C

<0.

019

<3.

5#

7112

h33m

49.3

s+

50d2

6m23

s0.

2068

4313

525

.22

E<

0.01

5<

2.7

#72

12h5

2m36

.9s

+28

d51m

51s

0.19

5079

B2

1250

+29

430

25.6

7E

<0.

005

<0.

8#

7313

h03m

46.6

s+

19d1

6m18

s0.

0635

1IC

4130

7023

.83

E<

0.03

8<

6.9

#74

13h0

6m21

.7s

+43

d47m

51s

0.20

2562

B3

1304

+44

013

725

.21

E<

0.02

1<

3.8

#75

13h0

8m37

.9s

+43

d44m

15s

0.03

5812

NG

C50

0361

23.2

6C

<0.

031

<5.

6#

7613

h14m

24.6

s+

62d1

9m46

s0.

1308

0572

24.5

1E

<0.

042

<7.

6#

7714

h00m

26.4

s+

17d5

1m33

s0.

0505

59C

GC

G10

3-04

188

23.7

3C

<0.

022

<4.

0#

7814

h00m

51.6

s+

52d1

6m07

s0.

1178

8717

624

.8C

<0.

021

<3.

8

Tab

le5.

2:-c

ontin

ued.

5.8: Appendix 109In

dex

RA

,Dec

zO

ther

nam

eS 1

.4G

Hz

P 1.4

GH

zR

adio

Mor

phol

ogy

τ pea

kN

(HI)

mJy

WH

z−1

1018

(Tsp

in/c

f)cm

−2

#79

14h0

8m10

.4s

+52

d40m

48s

0.08

2875

176

24.4

8E

<0.

018

<3.

4#

8014

h09m

35.5

s+

57d5

8m41

s0.

1798

7411

425

.02

C<

0.03

5<

6.5

#81

14h1

1m49

.4s

+52

d49m

00s

0.07

6489

393

24.7

5E

<0.

005

<1.

0#

8214

h47m

12.7

s+

40d4

7m45

s0.

1951

46B

314

45+

410

348

25.5

8E

<0.

006

<1.

1#

8315

h04m

57.2

s+

26d0

0m54

s0.

0539

84V

V20

4b19

024

.12

E<

0.01

2<

2.2

#84

15h0

9m50

.5s

+15

d57m

26s

0.18

7373

424

25.6

2C

<0.

005

<0.

9#

8515

h16m

41.6

s+

29d1

8m10

s0.

1298

8272

24.5

1E

<0.

059

<10

.7#

8615

h21m

16.5

s+

15d1

2m10

s0.

2147

7740

525

.74

C<

0.00

7<

1.3

#87

15h2

3m49

.3s

+32

d13m

50s

0.10

999

182

24.7

5C

<0.

016

<3.

0#

8815

h25m

00.8

s+

33d2

4m00

s0.

0815

5959

23.9

9E

<0.

032

<5.

9#

8915

h32m

02.2

s+

30d1

6m29

s0.

0653

3533

23.5

3C

<0.

064

<11

.7#

9015

h39m

01.6

s+

35d3

0m46

s0.

0778

3791

24.1

3C

<0.

019

<3.

5#

9115

h49m

12.3

s+

30d4

7m16

s0.

1115

824C

+30

.29

914

25.4

7E

<0.

004

<0.

8#

9215

h53m

43.6

s+

23d4

8m25

s0.

1176

064C

+23

.42

168

24.7

8E

<0.

034

<6.

2#

9315

h56m

03.9

s+

24d2

6m53

s0.

0425

3892

23.5

9E

<0.

021

<3.

9#

9415

h56m

11.6

s+

28d1

1m33

s0.

2079

2784

25.0

2E

<0.

024

<4.

4#

9515

h59m

54.0

s+

44d4

2m32

s0.

0417

3B

315

58+

448

5823

.37

C<

0.03

6<

6.6

#96

16h0

4m26

.5s

+17

d44m

31s

0.04

0894

NG

C60

40B

7323

.46

C<

0.04

0<

7.3

#97

16h0

6m16

.0s

+18

d15m

00s

0.03

69N

GC

6061

225

23.8

5E

<0.

010

<1.

8#

9816

h08m

21.1

s+

28d2

8m43

s0.

0501

82IC

4590

113

23.8

3E

<0.

016

<3.

0#

9916

h14m

19.6

s+

50d2

7m56

s0.

0602

5881

23.8

5E

<0.

025

<4.

5#

100

16h1

5m41

.2s

+47

d11m

12s

0.19

8625

B3

1614

+47

313

525

.18

E<

0.02

3<

4.2

#10

116

h24m

24.5

s+

48d3

1m42

s0.

0571

0467

23.7

2C

<0.

030

<5.

5

Tab

le5.

2:-c

ontin

ued.

Bibliography

Augusto, P., Gonzalez-Serrano, J. I., Perez-Fournon, I.,& Wilkinson, P. N. 2006, MNRAS,368, 1411

Alatalo, K., Blitz, L., Young, L. M., et al. 2011, ApJ, 735, 88

Allison, J. R., Curran, S. J., Emonts, B. H. C., et al. 2012, MNRAS, 423, 2601

Allison, J. R., Sadler, E. M., & Meekin, A. M. 2014, arXiv:1402.3530

Araya, E. D., Rodríguez, C., Pihlström, Y., et al. 2010, AJ, 139, 17

Assef, R. J., Kochanek, C. S., Brodwin, M., et al. 2010, ApJ, 713, 970

Baan, W. A., & Haschick, A. D. 1981, ApJ, 243, L143

Bahcall, J. N., Kirhakos, S., Saxe, D. H., & Schneider, D. P. 1997, ApJ, 479, 642

Baldwin J. A., Phillips M. M., Terlevich R., 1981, PASP, 93, 5

Becker, R. H., White, R. L., & Helfand, D. J. 1995, ApJ, 450, 559

Beswick, R. J., Peck, A. B., Taylor, G. B., & Giovannini, G. 2004, MNRAS, 352, 49

van Bemmel, I. M., Morganti, R., Oosterloo, T., & van Moorsel, G. 2012, A&A, 548,A93

Best, P. N., Kauffmann, G., Heckman, T. M., et al. 2005, MNRAS, 362, 25

Beswick, R. J., Peck, A. B., Pedlar, A., et al. 2004, The Interplay Among Black Holes,Stars and ISM in Galactic Nuclei, 222, 255

Bolton, R. C., Cotter, G., Pooley, G. G., et al. 2004, MNRAS, 354, 485

Bondi, M., Marchã, M. J. M., Polatidis, A., et al. 2004, MNRAS, 352, 112

Bondi, M., Pérez-Torres, M.-A., Dallacasa, D.,&Muxlow, T. W. B. 2005, MNRAS, 361,748

Booth, R. S., de Blok, W. J. G., Jonas, J. L.,&Fanaroff, B. 2009, arXiv:0910.3935

112 BIBLIOGRAPHY

van Breugel, W., Miley, G., & Heckman, T. 1984, AJ, 89, 5

Burns, J. O., Hanisch, R. J., White, R. A., et al. 1987, AJ, 94, 587

Caccianiga, A., Marchã, M. J., Antón, S., Mack, K.-H., & Neeser, M. J. 2002, MNRAS,329, 877

Carilli, C. L.,&Taylor, G. B. 2000, ApJ, 532, L95

del Castillo, E., Gavazzi, G.,&Jaffe, W. 1988, AJ, 95, 1340

Chandola, Y., Sirothia, S. K.,&Saikia, D. J. 2011, MNRAS, 418, 1787

Cicone, C., Maiolino, R., Sturm, E., et al. 2014, A&A, 562, A21

Cohen, A. S., Röttgering, H. J. A., Jarvis, M. J., Kassim, N. E., &Lazio, T. J. W. 2004,ApJS, 150, 417

Condon, J. J., Huang, Z.-P., Yin, Q. F.,&Thuan, T. X. 1991, ApJ, 378, 65

Conway, J. E. 1999, Highly Redshifted Radio Lines, 156, 259

Conway, J. E.,&Schilizzi, R. T. 2000, EVN Symposium 2000, Proceedings of the 5theuropean VLBI Network Symposium, 123

Curran, S. J., & Whiting, M. T. 2010, ApJ, 712, 303

Curran, S. J., Whiting, M. T., 2011, MNRAS, 413, 1165

Curran, S. J., Allison, J. R., Glowacki, M., Whiting, M. T.,&Sadler, E. M. 2013, MNRAS,431, 3408

Dasyra, K. M., Combes, F., Novak, G. S., et al. 2014, arXiv:1402.3187

Davis, T. A., Alatalo, K., Bureau, M., et al. 2013, MNRAS, 429, 534

O’Dea, C. P., Baum, S. A., & Gallimore, J. F. 1994, ApJ, 436, 669

Delhaize J., Meyer M. J., Staveley-Smith L., Boyle B. J., 2013, MNRAS, 433, 1398

DeBoer, D. R., Gough, R. G., Bunton, J. D., et al. 2009, IEEE Proceedings, 97, 1507

Dennett-Thorpe, J., & Marchã, M. J. 2000, A&A, 361, 480

Dickey, J. M. 1997, AJ, 113, 1939

Donoso, E., Yan, L., Tsai, C., et al. 2012, ApJ, 748, 80

Downes, D.,&Solomon, P. M. 1998, ApJ, 507, 615

van Driel, W., Arnaboldi, M., Combes, F., & Sparke, L. S. 2000, A&AS, 141, 385

Dwarakanath, K. S., Owen, F. N.,&van Gorkom, J. H. 1995, ApJ, 442, L1

Emonts, B. H. C., Morganti, R., Struve, C., et al. 2010, MNRAS, 406, 987

BIBLIOGRAPHY 113

Fabello S., Catinella B., Giovanelli R. et al., 2011, MNRAS, 411, 993

Fabello S., Kauffmann G., Catinella B. et al., 2011, MNRAS, 416, 1739

Fanti, R., Fanti, C., Schilizzi, R. T., et al. 1990, A&A, 231, 333

Fanti, C., Fanti, R., Dallacasa, D., et al. 1995, A&A, 302, 317

Fanti, C., Pozzi, F., Fanti, R., et al. 2000, A&A, 358, 499

Feretti, L., & Giovannini, G. 1994, A&A, 281, 375

Gallimore, J. F., Baum, S. A., O’Dea, C. P., Pedlar, A.,&Brinks, E. 1999, ApJ, 524, 684

Geréb, K., Morganti, R., Oosterloo, T. A., Guglielmino, G., & Prandoni, I. 2013, A&A,558, A54

van Gorkom, J. H., & Ekers, R. D. 1983, ApJ, 267, 528

van Gorkom, J. H., Knapp, G. R., Ekers, R. D., et al. 1989, AJ, 97, 708

Grossi, M., di Serego Alighieri, S., Giovanardi, C., et al. 2009, A&A, 498, 407

Guillard, P., Ogle, P. M., Emonts, B. H. C., et al. 2012, ApJ, 747, 95

Gupta, N., Salter, C. J., Saikia, D. J., Ghosh, T.,&Jeyakumar, S. 2006, MNRAS, 373,972

Healey, S. E., Romani, R. W., Taylor, G. B., et al. 2007, ApJS, 171, 61

Heckman, T. M., Smith, E. P., Baum, S. A., et al. 1986, ApJ, 311, 526

Helmboldt, J. F., Taylor, G. B., Tremblay, S., et al. 2007, ApJ, 658, 203

Huchtmeier, W. K. 1997, A&A, 319, 401

Iwasawa, K., Mazzarella, J. M., Surace, J. A., et al. 2011, A&A, 528, A137

Jaegers, W. J. 1987, A&AS, 71, 603

Johnston S., et al., 2008, ExA, 22, 151

Kauffmann, G., Heckman, T. M., Tremonti, C., et al. 2003, MNRAS, 346, 1055

Knapen, J. H., Laine, S., Yates, J. A., et al. 1997, ApJ, 490, L29

Kunert-Bajraszewska, M.,&Labiano, A. 2010, MNRAS, 408, 2279

Kunert-Bajraszewska, M., Gawroński, M. P., Labiano, A., & Siemiginowska, A. 2010,MNRAS, 408, 2261

Labiano, A., Vermeulen, R. C., Barthel, P. D., et al. 2006, A&A, 447, 481

Lah P., et al., 2007, MNRAS, 376, 1357

114 BIBLIOGRAPHY

Lah P., et al., 2009, MNRAS, 399, 1447

Landt, H., Cheung, C. C.,&Healey, S. E. 2010, MNRAS, 408, 1103

Lonsdale, C. J., Lonsdale, C. J., Smith, H. E., & Diamond, P. J. 2003, ApJ, 592, 804

Mack, K.-H., Feretti, L., Giovannini, G., & Klein, U. 1993, A&A, 280, 63

Mahony, E. K., Morganti, R., Emonts, B. H. C., Oosterloo, T. A., & Tadhunter, C. 2013,MNRAS, 435, L58

Marchã, M. J., Caccianiga, A., Browne, I. W. A., & Jackson, N. 2001, MNRAS, 326,1455

Martel, A. R., Baum, S. A., Sparks, W. B., et al. 1999, ApJS, 122, 81

Mauch, T., & Sadler, E. M. 2007, MNRAS, 375, 931

Massaro, F., Harris, D. E., Tremblay, G. R., et al. 2010, ApJ, 714, 589

Mezcua, M., Lobanov, A. P., Chavushyan, V. H.,&León-Tavares, J. 2011, A&A, 527, A38

Mirabel, I. F. 1990, ApJ, 352, L37

Morganti, R., Oosterloo, T.,&Tsvetanov, Z. 1998, AJ, 115, 915

Morganti, R., Oosterloo, T. A., Tadhunter, C. N., et al. 2001, MNRAS, 323, 331

Morganti, R., Oosterloo, T. A., Emonts, B. H. C., van der Hulst, J. M.,&Tadhunter,C. N. 2003, ApJ, 593, L69

Morganti, R., Oosterloo, T. A., Tadhunter, C. N., van Moorsel, G.,&Emonts, B. 2005,A&A, 439, 521

Morganti, R., de Zeeuw, P. T., Oosterloo, T. A., et al. 2006, MNRAS, 371, 157

Morganti, R., Peck, A. B., Oosterloo, T. A., et al. 2009, A&A, 505, 559

Morganti, R., Fogasy, J., Paragi, Z., Oosterloo, T.,&Orienti, M. 2013, Science, 341, 1082

Murray, C. E., Lindner, R. R., Stanimirović, S., et al. 2014, ApJ, 781, L41

Oosterloo, T.A.; Morganti, R.; Crocker, A. et al.; 2010; MNRAS; 409; 500

Oosterloo, T., Verheijen, M., & van Cappellen, W. 2010, ISKAF2010 Science Meeting

Orienti, M., Morganti, R.,&Dallacasa, D. 2006, A&A, 457, 531

Owsianik, I., & Conway, J. E. 1998, A&A, 337, 69

Parma, P., Murgia, M., Morganti, R., et al. 1999, A&A, 344, 7

Parma, P., Murgia, M., de Ruiter, H. R., et al. 2007, A&A, 470, 875

Paturel, G., Theureau, G., Bottinelli, L., et al. 2003, A&A, 412, 57

BIBLIOGRAPHY 115

Peck, A. B., Taylor, G. B., & Conway, J. E. 1999, ApJ, 521, 103

Pihlström, Y. M., Conway, J. E.,&Vermeulen, R. C. 2003, A&A, 404, 871

Readhead, A. C. S., Taylor, G. B., Xu, W., et al. 1996, ApJ, 460, 612

Richter, O.-G., Sackett, P. D., & Sparke, L. S. 1994, AJ, 107, 99

Roberts, M. S. 1970, ApJ, 161, L9

Romero-Cañizales, C., Pérez-Torres, M. A., Alberdi, A., et al. 2012, A&A, 543, A72

Rupke, D. S., Veilleux, S., & Sanders, D. B. 2005, ApJS, 160, 115

Saikia, D. J.,&Gupta, N. 2003, A&A, 405, 499

Sanders, D. B., Mazzarella, J. M., Kim, D.-C., Surace, J. A., & Soifer, B. T. 2003, AJ,126, 1607

Sault R. J., Teuben P. J., Wright M. C. H., 1995, ASPC, 77, 433

Serra P., et al., 2012, MNRAS, 422, 1835

Shostak, G. S., van Gorkom, J. H., Ekers, R. D., et al. 1983, A&A, 119, L3

Snellen, I. A. G., Mack, K.-H., Schilizzi, R. T.,&Tschager, W. 2004, MNRAS, 348, 227

Struve, C.,&Conway, J. E. 2010, A&A, 513, A10

Taylor, G. B., O’Dea, C. P., Peck, A. B., & Koekemoer, A. M. 1999, ApJ, 512, L27

Taylor, G. B., Healey, S. E., Helmboldt, J. F., et al. 2007, ApJ, 671, 1355

Teng, S. H., Veilleux, S.,&Baker, A. J. 2013, ApJ, 765, 95

Verheijen M., van Gorkom J. H., Szomoru A., Dwarakanath K. S., Poggianti B. M.,Schiminovich D., 2007, ApJ, 668, L9

Vermeulen, R. C., Pihlström, Y. M., Tschager, W., et al. 2003, A&A, 404, 861

de Vries, N., Snellen, I. A. G., Schilizzi, R. T., Mack, K.-H.,&Kaiser, C. R. 2009, A&A,498, 641

de Vries, N., Snellen, I. A. G., Schilizzi, R. T.,&Mack, K.-H. 2010, A&A, 521, A2

Westmeier, T., Jurek, R., Obreschkow, D., Koribalski, B. S.,&Staveley-Smith, L. 2014,MNRAS, 438, 1176

Yao, L., Seaquist, E. R., Kuno, N., & Dunne, L. 2003, ApJ, 597, 1271

York D. G., et al., 2000, AJ, 120, 1579

De Young, D. S., Roberts, M. S., & Saslaw, W. C. 1973, ApJ, 185, 809

De Young, D. S. 1993, ApJ, 405, L13

Young, L. M., Bureau, M., Davis, T. A., et al. 2011, MNRAS, 414, 940

Veilleux, S., Meléndez, M., Sturm, E., et al. 2013, ApJ, 776, 27

116 BIBLIOGRAPHY

university of groningen the role of neutral hydrogen in the life ......chapter 5 the hi absorption...

Documents