Cosmic radiative feedback from reionization By Ruben Salvaterra (OA-Brera) C. Burigana (IASF-Bologna) R. Schneider (OA-Firenze) T. Choudhury (Cambridge) A. Ferrara (SISSA) L. Popa (ISS Bucarest)

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Overview

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Radiative feedback from reionization The increase of temperature in ionized region leads to a dramatic suppression of the formation of low-mass galaxies. Suppression model: radiative feedback is effective in dark matter haloes with circular velocity below a critical value v crit ~ (2k B T/μm p ) where T is the average temperature of ionizing regions [~ 30 km/s for T=3x10 4 K] Filtering model: the average baryonic mass within haloes in photoionized regions is a fraction of the universal value: where M C is the mass of haloes that retain 50% of their gas mass (Gnedin 2000)

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Reionization model We implemented these two radiative feedback prescription in a well tested reionization model (Choudhury & Ferrara 2006). The main features of the model are: Inhomogeneous reionization assuming lognormal overdensity distribution Sources of reionization: PopIII stars: Salpeter IMF but metal free (Schaerer 06) PopII stars: Salpeter IMF, Bruzual & Charlot Quasars: important for z<6 Chemical feedback governs the transition from PopIII to PopII stars (Z crit =10 -5+/-1 Zsun): the two populations are coeval and PopIII stars can form also at relatively low-z.

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Effect of radiative feedback ionized regions M min (T=10 4 K) suppression filtering

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Results: suppression model

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Results: filtering model

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Reionization history and temperatures suppression filtering Reionization history Gas temperature

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 All-sky 21cm background signal require removal of foreground at a few x level filtering suppression

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, cm signal: detectability A successful detection requires: Δ  T b > 3 mK Δ(d  T b /df)> 0.6 mK MHz -1 Single-dish, all sky 21cm observations can discriminate between the two model in the frequency ranges obs =73-79 MHz (z= ) obs = MHz (z= )

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 CMB signal

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 CMB signal (TT, TE): detectability cosmic variance

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 CMB signal (EE): detectability x foreground 0.03

Schneider, Salvaterra, Choudhury, Ferrara, Burigana, Popa, 2008, MNRAS, 384, 1525 Conclusions Radiative feedback from reionization has important consequences on structure formation Different prescriptions for cosmic radiative feedback produce different reionization history Future 21cm and CMB polarization anisotropy observations can discriminate among different radiative feedback models. Foregrounds should be subtracted at percent level to discriminate between the suppression and the filtering model