Modelling radio galaxies in simulations:

CMB contaminants and SKA / Meerkat sources

by

Fidy A. RAMAMONJISOA

MSc Project

University of the Western Cape

Supervisor: Dr Catherine Cress

Introduction

Square Kilometre array:resolution less than 1milliarcsecond

108μm

Why do we model radio galaxies?

Relevant for SKA/MeerKAT science (eg. dark energy probe)

http://www.nrao.edu/whatisra/radiotel.shtml

MeerKAT (Karoo Array Telescope): more than 50 dishes, use mid-frequency

galaxies evolution and large-scale structure

1965

1992

2003

Penzias and Wilson

COBE

WMAP

Cosmic Microwave Background (CMB) :

Predicted by Gamov in 1948 Discovered by Penzias and Wilson in 1964

Precise measurement of the fluctuations in CMB by COBE in 1989

WMAP improved with more data in 2001

PLANCK will be launched 2009

Atacama Cosmology Telescope (ACT) will measure fluctuations on arcminute angular scale

Cosmic Microwave Background (CMB)

CMB: relic radiation from the early universe emitted when the universe was about 400000 yrs old (z=1100), has a thermal black body of 2.73 K.

ACT

http://www.space.com/scienceastronomy

AimOne of CMB experiments goals

Counting clusters at different times (redshift)

Relevant to dark energy constraints

BUTWhy?

How?Use CMB observations

through Sunyaev- Zeldovich (SZ) effect

Counting is difficult because of point sources and radio sources

We aim at modelling spatial distribution (number density) and

flux of radio sources using N-body simulation

e-

e-

e-

e-

e-

e-

e-

e-

e-

TTelectronelectron = 10 = 1088 K K

Hot electron gas

Inte

nsity

(M

Jy/s

r)

Frequency (GHz) -0.05

0.00

0.05

ACT frequencies

145 GHz decrement

220 GHz null

270 GHz increment

What is Sunyaev Zeldovich (SZ) effect?

•Distortion of CMB spectrum by inverse Compton scattering

•SZ is redshift independent

Credit: D. Spergel

100 200 300

SZ

Point sources

synchrotron

Dust

BLAZAR

X ray OpticalRadio cont. 21 cm

e-

e-

e-

e-

e-

e-

e-

e-

e-

TTelectronelectron = 10 = 1088 K K

Hot electron gas

SZ contaminants

Inte

nsity

(M

Jy/s

r)

Frequency (GHz) -0.05

0.00

0.05

ACT frequencies

145 GHz decrement

220 GHz null

270 GHz increment

Credit: D. Spergel

Method

•Use Millennium Run and semi analytical model of galaxy formation and evolution (Croton et al. 2006, De Lucia & Blaizot 2007)

•Extend the semi analytical model to follow black hole follow black hole mass accretion and its conversion to radiationmass accretion and its conversion to radiation

Method Use the Millennium simulation (Virgo consortium) to build the modelMillennium Run: simulation of 1010 dark matter particles in a cubic region 500h-1Mpc on a side in the ΛCDM cosmological framework (Springel et al. 2005)

Particle mass:8.6x108h-1Mʘ

Outputs stored in a database: use Structured Query Language (SQL) to make a query

http://www.g-vo.org/Millennium

Method

1

1

1

1

1

2

2

3

3

4

4

4

4

4

5

5

6

6

6

7

7

1. Dark matter collapses under gravity and forms halos 1, 2, 3, 4.

2. Gas cools in halos 1, 2, 3, 4 and forms disks and stars. Halo 5 collapses.

3. Halos 2 and 3 merge with halo 1. Gas cools in halo 4 and 5 forming stars. Halo 6 collapses.

4.Galaxy 2 merges with galaxy 1 and form a spheroid (elliptical) as they have similar size. Galaxy 3 is a satellite. Halos 4 and 5 merge. Gas cools and stars form in halo 6. Halo 7 collapses.

5. More gas cools into disk in galaxy 1. Galaxy 5 merges with galaxy 4. Galaxy 5 is much smaller so no spheroid forms. Gas cools into halo 7 forming stars.

SEMI ANALYTICAL MODEL

z=3

z=2

z=1

z=0

N-body simulation

Method

Y

dt

dz

dz

dM

dt

dM BHBHBHM

GHz

GHz

GHz

GHzGHz

dL

dL

f 910

10

)15145(

)15145(145

0º<i<10º

Use SED of blazar

Use SED of normal radio galaxies

)()( 145 tLft bolGHzACTL

24

)(

L

ACT

d

tLS

Find the progenitors at later z2 of the whole galaxies at z1

Extract galaxies in halo centralMvir>2x1014h-1Mʘ at z1

Assume a random inclination i of radio source

Assume a fraction f of total Lbol (t) is radio luminosity

fluctuation in CMB at t

mJy

SK

3.010

N

2

1)( cMtL BHbol

(Marulli et al. 2007)

Obsevations

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1.5

-1

-0.5

0

0.5

1

1.5RLF with luminosity cut off at 151 MHz (High luminosity part of the RLF)

Redshift z

Nu

mb

er

de

nsi

ty (

log

sca

le)

in G

pc-3

Radio luminosity function (number density of radio sources): obtained by fitting data from surveys of radio sources

Model ‘C’ of luminosity function (C.J. Willott et al. 2000).

Model of RLF (J.Jarvis et al.2001)

0 0.5 1 1.5 2 2.5 3 3.5 40

500

1000

1500

2000

2500

3000

3500RLF with luminosity cut off L=10

26 W.Hz

-1.sr

-1 at 151 MHz

Redshift z

Num

ber

de

nsi

ty in

Gp

c-3

Progenitors of the brightest galaxy (mag_v~-24.4) identified at z=0

Preliminary results

0 0.5 1 1.5 2 2.5 3 3.5 410

-4

10-3

10-2

10-1

Redshift z

Bla

ck h

ole

mas

s in

uni

ts o

f 101

0h-1

Msu

n (s

emilo

g pl

ot)

0 1 2 3 4 5 6 710

-4

10-3

10-2

10-1

Redshift z

Bla

ck h

ole

mas

s in

uni

ts o

f 101

0h-1

Msu

n (s

emilo

g pl

ot)

Progenitors of a galaxy at z=1 in the most massive halo (centralMvir~8x1014h-1Mʘ massive halos)

Preliminary results

MBH=0.43x1010h-1MʘMBH=0.09x1010h-1Mʘ

Preliminary results

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.410

0

101

102

103

Redshift zTe

mp

era

ture

flu

ctu

atio

n (

mic

roK

elv

in)

z

σ (μK)

0.54

226

1.03

45

1.57

16

2.16

7

Temperature fluctuation (μK) from radio source vs redshift z

Preliminary results

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

100

Redshift z

Flu

x o

f ra

dio

so

urc

es

log

S (

mJy

)

z

Sν

(mJy)

0.54

6.8

1.03

1.4

1.57

0.5

2.16

0.2

Flux of radio sources at 145 GHz vs redshift z

Future objectives

3

18, .2001.010

skmVf

MMM virhotBH

AGNRBH

Radio mode: accretion of hot gas

Quasar mode : major merger and cold gas accretion

21, )/.280(1 vir

coldBHQBH Vskm

mfM

central

satBHBH m

mff

03.0BHf

Include Active Galactic Nuclei (AGN) feedbackInclude Active Galactic Nuclei (AGN) feedback

Model radio emission fromModel radio emission from star formationstar formation

16105.7

yrMAGNControl the efficiency of accretion

Efficient at low redshift Efficient at z>2

Conclusion The results constitute a first step for the investigation of the growth of

supermassive black hole

Currently we investigate how best to relate the black hole growth to the expected radio emission (as in Marulli et al. 2007)

The most massive black holes are present today (z=0) in simulations

References Croton D. J., Springel V. et al., 2006, MNRAS, 365, 11

Marulli F., Bonoli S., Branchini E., Moscardini L., Springel V., 2007, MNRAS, submitted

Willott C.J., Rawlings S., Blundell K. M., Lacy M., Eales S.A., 2000, MNRAS, 322 (2001) 536-552

http://chandra.harvard.edu/

http://cse.ssl.berkeley.edu/