by fidy a. ramamonjisoa msc project university of the western cape

by

Fidy A. RAMAMONJISOA

MSc Project

University of the Western Cape

Supervisor: Prof Catherine Cress

Modelling radio galaxies in simulations:

CMB contaminants and SKA / Meerkat sources

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

AimOne of CMB experiments goals

Counting clusters at different times (redshift)

Relevant to dark energy constraints

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

INTRODUCTION

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Inte

nsity

(M

Jy/s

r)

Frequency (GHz) -0.05

0.00

0.05

ACT frequencies

145 GHz decrement

218 GHz null

270 GHz increment

Credit: Spergel D.

e-

e-

e-

e-

e-

e-

e-

e-

e-

TTelectronelectron = 10 = 1088 K K

Hot electron gas

Sunyaez-Zeldovich effect (SZE) in galaxy clusters

Distortion of CMB black body by inverse Compton scattering

2A

eSZE

D

TMdT

redshift independent effect

SZ surveys detect clusters

Thermal SZ270-300 microKelvin

Kinetic SZ10-20 microKelvin

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Methodology

•Millennium Run and semi analytical modelsemi 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

Millennium 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

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

AGN feedbackRadiative accretion efficiency

(not yet well known)

Radio mode Quasar mode

SMBH growth triggered by mergers- cold disk gas driven onto black hole

(Kauffmann & Haeanelt 2000)

Hot gas from surrounding hot halo accretes onto SMBH

Efficient at

7.0z

sunBH MM 810

Efficient at

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

1z

2

1cML BHbol

)()(

)()(

21

21

ztzt

zMzMM BHBHBH

Find progenitors at z1of all galaxies at z2

bolfLL

24 Ld

LS

mJySS cut 1 cutL

BH Sfc

dM

2

241

Count radio source

MODELf fraction of conversion to radio

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Fossati G. et al. (1998)

Average SED of blazars grouped by powers

Redshift distribution of blazars normalized

Flux density limit 1 mJy at 2.7 GHz

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Results

Redshift distribution of blazars normalized

Flux density limit 1 mJy at 2.7 GHz

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

ResultsFossati G. et al. (1998)

Average SED of blazars grouped by powers

Redshift distribution of blazars normalized

Flux density limit 1 mJy at 2.7 GHz

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

ResultsFossati G. et al. (1998)

Average SED of blazars grouped by powers

200r

r

123 .10 HzWP

Total surface density of radio galaxies vs.

Simulation+observation

Lin & Mohr (2007)simulation

Luminosity

200r

r

at 1.4 GHz

ResultsRedshift up to 0.06Radio galaxies

galaxies

BL LacsFRI

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Results

200r

rsunMh 11410

sunMh 11410

Surface density of radio sources vs.

2<Mvir<6

6<Mvir<10Mvir>10

Unit:

200r

r

Radio sources are concentrated in low mass clusters

Density of radio sources maximum near the centre

123 .10 HzWPLuminosity

at 1.4 GHz

Redshift 0.05

sunMh 11410

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Temperature (microK) vs redshift z Flux (mJy) vs z

Temperature fluctuations and fluxes caused by blazars in clusters binned in cluster mass at 145 GHz

Results

CMB contamination by radio galaxies and quasars

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

Summary• The model is able to reproduce fairly well the observed redshift distribution of radio

sources

• The surface density of simulated blazars are in agreement with Lin & Mohr for small radial distance from the centre of the cluster.

• It predicts high concentration of radio sources close to the centre of clusters.

• Radio sources are more concentrated in low mass clusters .

• Contaminations by blazars are not negligible at local redshift (z<0.1).

• The average temperature fluctuation in CMB caused by BL Lacs is 5 microK at z=0.01

(almost at the same order as the kinetic SZ signature of an average cluster mass).

• At high redshift (z>1), the fluctuation in CMB temperature produced by blazars appears to be very significant (about 300-350 microK, similar to temperature fluctuations from the thermal SZ effect).

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09

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

• Dunlop J. S., Peacock J. A., 1990, MNRAS 247, 19-42

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

• Lin Y. T., Mohr J. J., 2007, astro-ph/0612521v2

SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09