Mário Santos1 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Epoch of Reionization / 21cm simulations Mário Santos CENTRA - IST

Mário Santos2 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October cm signal - simulation Dark matter / radiative transfer simulation: 100 Mpc/h side, (720)3 cells, » 24 billion particles (Shin et al., 2007, ArXiv e-prints, 708) Brightness temperature maps (21cm HI line) Post-processing with fast semi- numerical prescription to get spin temperature (Santos et al., 2008, ApJ, 689, 1) Ionization fraction ( º = 87 MHz) Sky simulation ( º = 87 MHz)

Mário Santos3 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October cm signal - simulation Ionization fraction ( º = 87 MHz) Sky simulation ( º = 87 MHz) 21cm signal: TS: HI spin temperature – depends on collisional coupling, Ly ® coupling, gas temperature (X-ray heating)

Mário Santos4 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October cm simulation – Ly ® fluctuations Top – left: Sky simulation with homogeneous Ly ® Top – right: Sky simulation with Ly ® fluctuations Bottom - left: power spectrum of the Ly ® photon flux Important for z & 15 Dominates over collisions up to z=22 z=20 mK

Mário Santos5 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October cm simulation – X-ray fluctuations Top – left: sky simulation with homogeneous X-ray heating Top – right: sky simulation with fluctuations in the gas temperature due to X-rays Bottom – left: power spectrum of the gas temperature Important for z > 10! mK z=15

Mário Santos6 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 EoR / 21cm sky simulation Brightness temperature maps: Box size Mpc/h (50’) (7 MHz) Box resolution Kpc/h (4’’) (10 KHz) 6 < z < 25 (55 MHz < º < 203 MHz) Available for SKADS use Santos et al., 2008, ApJ, 689, 1

Mário Santos7 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October cm signal – redshift evolution Average temperature Top: Spin (dotted); gas (red dashed); CMB (solid) Bottom: brightness temperature with all fluctuations (black) and without x-ray fluctuations (red) Power spectrum evolution Signal increases with redshift! (up to z ~ 16)

Mário Santos8 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Power spectrum Expected range measured by 1st generation experiments (e.g. LOFAR) Expected range measured by SKA

Mário Santos9 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Power spectrum - errors T sky ~ MHz Bandwidth ~ 8 MHz per redshift t tot =1000 hours Blue (SKA type): A eff =4000 m MHz FoV ~ 200 deg 2 D max =5 Km (with 70% of A eff ) D min =15 m Green (LOFAR type): 130 m 2 z=6 ( º =203 MHz) FoV ~18 deg 2 (x2) D max =1 Km (with 80% of A eff ) D min =100m Red solid line: brightness temperature 3-d power spectrum with all fluctuations included Dashed lines: total error in the power spectrum; bins=0.5k

Mário Santos10 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Map making - 1 z=7, º =177 MHz, µ =1 degree, ¢µ =9’’ z=7, º =177 MHz, ¢º =2 MHz, µ =1 degree, ¢µ =35’’ Signal + Noise Signal T (mK)

Mário Santos11 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Map making - 2 Z=9.2, º =140 MHz, µ =32’, ¢µ =4.8’’ Z=9.2, º =140 MHz, ¢º =2MHz, µ =32’, ¢µ =46’’ T (mK) Signal Signal + Noise

Mário Santos12 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Map making - 3 z=12, º =110 MHz, µ =32’, ¢µ =4.8’’ z=12, º =110 MHz, ¢º =2 MHz, µ =32’, ¢µ =0.94’ Signal Signal + Noise T (mK)

Mário Santos13 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Note: SKA Field of View Need larger simulations for proper testing of the observation pipeline Use semi-numerical dark matter simulation with analytical prescription for ionized bubbles (in preparation) Also good for fast power spectrum generation ~ 200 degree 2 50’ Fast semi- numerical dark matter / ionized bubbles simulation 21cm simulation

Mário Santos14 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Analytical models – x i power spectrum Useful to quickly explore the full astrophysical and cosmological parameter space for 21cm surveys! Easy to probe both large and small scales Left: power spectra of the ionization fraction (divided by the dark matter one)

Mário Santos15 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Analytical models – 21cm power spectrum Power spectra of the 21cm brightness temperature for the simulation (black) versus one semi-analytical model OK for z < 10 (e.g. first generation experiments) At z & 10 (SKA…) X-ray and Ly ® fluctuations are important – need further improvements

Mário Santos16 EoR / 21cm simulations 4 th SKADS Workshop, Lisbon, 2-3 October 2008 What can we learn? Probe a crucial step in the evolution of the Universe - formation of first non- linear structures (first stars and galaxies) Complex Reionization history: 6 < z <20 ! (currently very little experimental data) Astrophysical parameters: x i, Ly ® flux, gas temperature, star formation, photon escape fraction… Cosmological parameters:  ¤,  m h 2,  b h 2, n s, neutrino mass… M.G. Santos and A. Cooray, Phys.Rev. D74 (2006) Mao et al, PRD 78, (2008) McQuinn et al, ApJ 653, 815 (2006)