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 10 8 μm Why do we model radio galaxies? Relevant for SKA/MeerKAT science (eg. dark energy probe) MeerKAT (Karoo Array Telescope): more than 50 dishes, use mid-frequency galaxies evolution and large-scale structure

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 yrs old (z=1100), has a thermal black body of 2.73 K. ACT

Aim One of CMB experiments goals Counting clusters at different times (redshift) Relevant to dark energy constraints BUT Why? 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-e- e-e- e-e- e-e- e-e- T electron = 10 8 K Hot electron gas Intensity (MJy/sr) Frequency (GHz) 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

SZ Point sources synchrotron Dust BLAZAR X ray Optical Radio cont. 21 cm e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- T electron = 10 8 K Hot electron gas SZ contaminants Intensity (MJy/sr) Frequency (GHz) 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) follow black hole mass accretion and its conversion to radiationExtend the semi analytical model to follow black hole mass accretion and its conversion to radiation

Method Use the Millennium simulation (Virgo consortium) to build the model Millennium Run: simulation of dark matter particles in a cubic region 500h -1 Mpc on a side in the ΛCDM cosmological framework (Springel et al. 2005) Particle mass:8.6 x 10 8 h -1 M ʘ Outputs stored in a database: use Structured Query Language (SQL) to make a query

Method Dark matter collapses under gravity and forms halos 1, 2, 3, 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 0 º <i<10 º Use SED of blazar Use SED of normal radio galaxies Find the progenitors at later z2 of the whole galaxies at z1 Extract galaxies in halo centralMvir>2x10 14 h -1 M ʘ at z1 Assume a random inclination i of radio source Assume a fraction f of total L bol (t) is radio luminosity fluctuation in CMB at t N (Marulli et al. 2007)

Obsevations 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)

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

Progenitors of a galaxy at z=1 in the most massive halo (centralMvir~8x10 14 h -1 M ʘ massive halos) Preliminary results M BH =0.43x10 10 h -1 M ʘ M BH =0.09x10 10 h -1 M ʘ

Preliminary results z σ (μK) Temperature fluctuation (μK) from radio source vs redshift z

Preliminary results z S ν (mJy) Flux of radio sources at 145 GHz vs redshift z

Future objectives Radio mode: accretion of hot gas Quasar mode : major merger and cold gas accretion  Include Active Galactic Nuclei (AGN) feedback  Model radio emission from star formation Control the efficiency of accretion Efficient at low redshiftEfficient 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)   Willott C.J., Rawlings S., Blundell K. M., Lacy M., Eales S.A., 2000, MNRAS, 322 (2001)