Sean Passmoor Supervised by Dr C. Cress Simulating the Radio Sky

Simulating the Radio Sky: two goals 1. Compare predictions of ΛCDM + galaxy evolution models with observations * HI sources * Radio continuum sources * CMB foregrounds - see talks by Opolot and Ramamonjisoa 2. Make “fake skies” for MeerKAT/SKA Simulations we are working with: 1. DM only simulation on CHPC (256 3 particle): test run for CHPC 2. GIMIC simulation on CHPC (with Theuns): Gas + DM, 400*10 6 particles, 32MPc box 3. Millenium simulation (already run, with semi-analytic modelling to get galaxy properties, query with SQL)

N-body simulation flavours: Dark Matter only: represent ~ M ☉ as a single particle allow particles to interact gravitationally gives info on non-linear evolution of density fluctuations Dark Matter+Semi-Analytic Models identify “halos” (clumps) in dark matter simulation trace merger history of halos use basic physics (gas cooling etc.) to “paint” galaxies Dark Matter + Smoothed Particle Hydrodynamics model gas explicitly can add in star formation etc., depending on application ☉

‏ Blue Gene/P e1350

Simulations at the CHPC  Dark Matter Only : particles, 50 h -1 Mpc box  science:  Bryan and Cress (2007) – here a test run for full SPH sim  Dark Matter +SPH (with Tom Theuns at ICC, Durham)‏  32 h -1 Mpc, 400*10 6 particles Re-simulation of Millenium with Gas  Gadget3 Star-formation,tracking metal production and distribution  Future:  Study gas dynamics in environment  of clusters at high-redshift  Sunyaev-Zeldovich studies  Fake skies for MeerKAT/SKA

Simulating the radio sky using existing simulations: The Millenium Simulation: DM-only simulation + SAMS galaxy and DM properties available via SQL database The simulation output consists of 64 snapshots of the simulation state at various times Semi analytic models done by DeLucia & Blaizot (2006) Can look at galaxies in each snapshot or use Kitzbichler & White (2006) “pencil-beam” Springel et. al.

Semi-Analytic Models for Galaxy: Evolution: basics 1. Dark matter over-densities collapse under gravity to form halos 2. Gas falls into halos, cooling and forming a disk 3. Star formation occurs, re-heating some gas (Feedback)‏ 4. Spheroids (eg ellipticals) form when disks merge 5. Gas cools around spheroids forming disk Kauffmann et al 1999, Croton et al. 2006, Bower et al. 2006

Simulating the radio sky using existing simulations: An Example The mock sky for a 2% SKA A e /T sys = Hour Pointing Velocity width of 100 Km.s 1420MHz (473kHz) Detected 406 sources with a S/N > 5 Area of the pencil beam from the mock catalogue is 2 deg 2

Cold Gas Evolution in Millenium Sim Knowledge of cold gas evolution is important for Dark Energy experiment design

The Making of a mock catalogue Blaizot et al (2005)‏

Making Mock HI sky for MeerKAT: HI Mass detectable

Making Mock HI sky for MeerKAT: Redshift Distribution

Conclusion Simulating the Radio sky provides a way to examine the effectiveness of galaxy evolution models. Important for experiment design Thanks Daniel Cunnama