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Wallaby science meeting - Dec 2 2010

Westerbork ultra-deep HI observations at z=0.2

Glenn Morrisson (Hawaii)Bianca Poggianti (Padova)David Schiminovich (Columbia)Arpad Szomoru (JIVE)Marc Verheijen (Kapteyn)Min Yun (UMASS)

Aeree Chung (CfA)Ryan Cybulski (UMASS)Boris Deshev (Kapteyn)K.S. Dwarakanath (RRI)Jacqueline van Gorkom (Columbia)Maria Montero-Castano (Columbia)


HI, ICM, SFR, SFH, SPs and the environment

Bravo

-Alfaro

et al, 2001

Poggian

ti & van

Gorko

m, 2

001

Coma Abell 2670

What is the role and fate of cold gas in galaxy evolution?


Why clusters at higher redshift?

! Exploratory steps towards understanding the role and fate of cold gas in cosmological evolution.

Why Z~0.2 ?! Highest redshift for ‘practical’ HI imaging with existing arrays

! Lowest redshift where cosmological evolutionary effects are seen

Content of galaxy clusters and the surrounding field evolves over cosmic time.


0 0.1 0.2 0.3 0.4 0.5

redshift

0

0.1

0.2

0.3

0.4

blu

e fr

action

Abrah

am et al, 1

996

Butcher-Oemler effect

The fraction of blue (starforming?) galaxies in clusters increases with redshift and peaks in cluster outskirts.

A963

Key question: different accretion rate/efficiency or different field population?

Butch

er & O

emler, 1

984


Morphological mix in clusters depends on redshift and compactness

Fasano et al, 2

000

• HEC LEC


Clusters of different compactness

Concentration of ellipticals:

High " S0/E low Low " S0/E high

Fasano et al, 2000


Goals of HI observations at intermediate z

• Characterize nature of blue galaxy population " gas content, SFR, stellar populations

• Witness galaxy transformation in various environments " which physical mechanisms dominate where? gas accretion and depletion

• SFR versus environment and gas content

• Evolving !HI from blind HI 21cm emission surveys

• Evolving HI Mass Function? " HIMF in different environments

• HI based Tully-Fisher and rotation curve studies


1 Mpc 1 Mpc

z=0.188z=0.206INT - B,R

A tale of two clusters

Abell 2192Abell 963

work in progress( thesis Boris Deshev )


1 Mpc 1 Mpc1 Mpc1 Mpc

z=0.188z=0.206INT - B,R

A tale of two clusters

Abell 2192Abell 963

work in progress( thesis Boris Deshev )


INT - 2.5m SDSS

SDSS @ Z=0.2 is of insufficient qualityto determine morphologies and detect LSB galaxies.

B: 5x15minR: 5x 6min


Ultra-deep WSRT observations

• Minimum detectable HI mass: 2x109 Msun over 150 km/s profile width

(4" in each of 3 spectral resolution elements)

• Corresponding limiting column density:

3x1019 (cm-2) over 80 km/s profile width at 7".

This requires: 78x12hr for A2192 at z=0.188

117x12hr for A963 at z=0.206


Survey Volume & Large Scale Structure

SDSS redshift slice

325 Mpc

combined volume: 7x10 Mpc4 3

HIPASS

Alfalfa


WSRT observational setup

• Long-term program over 8 semesters

• 8x10MHz bands, overlapping to cover 1160-1220 MHz Z = 0.164-0.224 , surveyed volume # 70,000 Mpc3

• 8x256 channels, covering 18,000 km/s velocity range 20 km/s velocity resolution (after Hanning smoothing)

• dual polarisation, 2-bit correlation, recirculation

• 117x12hr on Abell 963 , 78x12hr on Abell 2192

rms noise per channel: 14 $Jy and 17 $Jy (%V=80 km/s)

~5-15% lost to RFI, antenna 5 offline (APERTIF prototype)

Verheijen et al, 2007, A

pJ Lett, 6

68, 9


WSRT observational setup

• Long-term program over 8 semesters

• 8x10MHz bands, overlapping to cover 1160-1220 MHz Z = 0.164-0.224 , surveyed volume # 70,000 Mpc3

• 8x256 channels, covering 18,000 km/s velocity range 20 km/s velocity resolution (after Hanning smoothing)

• dual polarisation, 2-bit correlation, recirculation

• 117x12hr on Abell 963 , 78x12hr on Abell 2192

rms noise per channel: 14 $Jy and 17 $Jy (%V=80 km/s)

~5-15% lost to RFI, antenna 5 offline (APERTIF prototype)

Verheijen et al, 2007, A

pJ Lett, 6

68, 9

A963 A2192

semester # measurements

2005 -A 20-B 15

2006 -A 33 15-B 5

2007 -A 33 12-B 3

2008 -A 31 8-B 15

total 117 73

hours 1404 876

pilot study


achieved rms noise

A2192

A963

Flagged: 5-8% 15-17%


achieved rms noise

A2192

A963

Flagged: 5-8% 15-17%

before after

0 256 0 256channel

tim

e

0 hr

12 hr

channel

10 MHz 10 MHz


IF-based selfcal


Abell 2192 Abell 963

" = 7 $Jy/beam (confusion limited) " = !12 $Jy/beam (DR limited)

continuum

SFR # 10 Msun/yr ( deep GALEX data more sensitive )


%V = (1+Z)!C!%f/f0 = (1+Z)!8.24 km/s

Velocity smoothing the data cubes:

R2 : R = 2%V = 20 km/s # 1544 channelsR4 : R = 4%V = 40 km/s # 768 channelsR6 : R = 6%V = 60 km/s # 510 channelsR8 : R = 8%V = 80 km/s # 383 channels


Abell 2192 Abell 963

R=80 km/s" = 17 $Jy/beam " = 14 $Jy/beam

Detection criteria: 1x8" or 1.5x6" or 2x5" or 3x4" or 4x3" in N consecutive spectral resolution elements.

line cubes

Spectrally smoothed to R=20, 40, 60, 80 km/s


R2 R4 R6 R8 R2 R4 R6 R8

positive detections negative detections

1x8"

2x5"

3x4"

4x3"

simple source finding results


R-band B-band Near-UV Far-UVINT optical GALEX ultra-violet

Stellar counterparts


A 2192 A 963

Cube dimensions : 9.5 x 9.5 x 325 Mpc3

Synthesized beam size : 65 x 80 kpc2 x 80 km/s


0.164 redsihft 0.224Cube dimensions: 9.5 x 9.5 x 85 Mpc3

surroundings of Abell 963

85 Mpc


Examples of detections (based on pilot data)


detected HI masses

Determination of HI Mass Function and !HIrequires completion corrections : to be done...

144 HI detectionswith SDSS counterparts

(both clusters combined)


MHI =

2x10

9

Relative HI gas mass fractions


Colour-Magnitude diagram

: optical redshifts

: HI detections


Stacking HI spectra (based on pilot data)

Average HI mass: 2x10 M •&9~


Conclusions

• Expected rms achieved with the WSRT

• HI emission from >150 individual galaxies at Z#0.2

• Blind HI surveys uncover LSS not seen by SDSS

• Blue ‘BO-galaxies’ gas-poor wrt similar field galaxies

• !HI and HI-based TF at Z=0.2 expected soon

The HI-universe at Z#0.2 is under reach !

westerbork ultra-deep hi observations at z › research › wallaby › wallaby2010 › mver… ·...

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