T. Roy Choudhury

The escape fraction of ionizing photons from high-redshift galaxies from data-constrained reionization models

The escape fraction, fesc, of ionizing photons from high-redshift galaxies is a key parameter to understand cosmic reionization and star formation history. Yet, in spite of many efforts, it remains largely uncertain. We propose a novel, semi-empirical approach based on a simultaneous match of the most recently determined luminosity functions of galaxies in the redshift range 6 ≤ z ≤ 10 with reionization models constrained by a large variety of experimental data. From this procedure, we obtain the evolution of the best-fitting values of fesc along with their 2σ limits. We find that, averaged over the galaxy population, (i) the escape fraction increases from fesc = 0.068 +0.054 −0.047 at z = 6t ofesc = 0.179 +0.331 −0.132 at z = 8 and (ii) at z = 10 we can only put a lower limit of fesc > 0.146. Thus, although errors are large, there is an indication of a 2.6 times increase of the average escape fraction from z = 6 to 8, which might partially release the ‘starving reionization’ problem.

Cosmic reionization after Planck

Cosmic reionization holds the key to understand structure formation in the Universe, and can inform us about the properties of the first sources, as their star formation efficiency and escape fraction of ionizing photons. By combining the recent release of Planck electron scattering optical depth data with observations of high-redshift quasar absorption spectra, we obtain strong constraints on viable reionization histories. We show that inclusion of Planck data favors a reionization scenario with a single stellar population. The mean

On the use of seminumerical simulations in predicting the 21-cm signal from the epoch of reionization

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Theoretical and observational constraints on the H i intensity power spectrum

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The effect of peculiar velocities on the epoch of reionization 21-cm signal

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21-cm signal from cosmic dawn - II: Imprints of the light-cone effects

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An improved model of H ii bubbles during the epoch of reionization

z=10.6

Modelling the cosmic neutral hydrogen from DLAs and 21-cm observations

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21-cm signature of the first sources in the Universe: prospects of detection with SKA

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Measuring the equation of state of the high-z intergalactic medium using curvature statistics

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