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Modelling radio galaxies in simulations: CMB contaminants and SKA / Meerkat sources. by Fidy A. RAMAMONJISOA MSc Project University of the Western Cape. Supervisor : Prof Catherine Cress. SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09.
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Modelling radio galaxies in simulations: CMB contaminants and SKA / Meerkat sources by Fidy A. RAMAMONJISOA MSc Project University of the Western Cape Supervisor: Prof Catherine Cress SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Counting is difficult because of point sources and radio sources We aim at modelling spatial distribution (number density) and fluxof radio sources using N-body simulation Aim INTRODUCTION One of CMB experiments goals Use CMB observations through Sunyaev- Zeldovich (SZ) effect Counting clusters at different times (redshift) How? Relevant to dark energy constraints SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
redshift independent effect 0.05 Cosmic Microwave Background Hot electron gas Intensity (MJy/sr) e- 0.00 e- e- e- Cluster -0.05 Frequency (GHz) e- ACT frequencies e- e- e- 145 GHz decrement 218 GHz null 270 GHz increment e- Telectron = 108 K Sunyaez-Zeldovich effect (SZE) in galaxy clusters SZ surveys detect clusters Distortion of CMB black body by inverse Compton scattering Thermal SZ270-300 microKelvin Kinetic SZ10-20 microKelvin Credit: Spergel D. SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Methodology • 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 mass 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 feedback Radiative accretion efficiency (not yet well known) Quasar mode Radio mode Hot gas from surrounding hot halo accretes onto SMBH SMBH growth triggered by mergers- cold disk gas driven onto black hole (Kauffmann & Haeanelt 2000) Efficient at Efficient at SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Find progenitors at z1of all galaxies at z2 f fraction of conversion to radio MODEL Count radio source SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Results Average SED of blazars grouped by powers Fossati G. et al. (1998) 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 Average SED of blazars grouped by powers Fossati G. et al. (1998) 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 Average SED of blazars grouped by powers Fossati G. et al. (1998) 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 Simulation+observation Lin & Mohr (2007) Redshift up to 0.06 Radio galaxies galaxies simulation BL Lacs FRI Luminosity Total surface density of radio galaxies vs. at 1.4 GHz SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Results • Radio sources are concentrated in low mass clusters • Density of radio sources maximum near the centre Redshift 0.05 2<Mvir<6 6<Mvir<10 Mvir>10 Unit: Luminosity at 1.4 GHz Surface density of radio sources vs. SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Results CMB contamination by radio galaxies and quasars Flux (mJy) vs z Temperature (microK) vs redshift z Temperature fluctuations and fluxes caused by blazars in clusters binned in cluster mass at 145 GHz 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