arXiv subjects

Saumyadip Samui

Publications and source records attributed to Saumyadip Samui.

21 records · Page 2Linked to original sources

arXiv2007

Probing the star formation history using the redshift evolution of luminosity functions

We present a self-consistent, semi-analytical LCDM model of star formation and reionization. For the cosmological parameters favored by the WMAP data, our models consistently reproduce the optical depth to reionization, redshift of reionization and the observed luminosity functions (LF) and hence the star formation rate (SFR) density at 3 8. Molecular cooled halos, which may be important for reionizing the universe, are not detectable in the present deep field observations. However, their presence and contribution to reionization can be inferred indirectly from the redshift evolution of the LF at 6<z< 12.Accurately measuring the LF at high z can be used to understand the nature of star formation in the dark ages and probe the history of reionization. (Abridged)

astro-ph↗

arXiv2005

Can Cosmic Rays Heat the Intergalactic Medium?

Supernova explosions in the early star forming galaxies will accelerate cosmic rays (CRs). CRs are typically confined in the collapsed objects for a short period before escaping into the intergalactic medium (IGM). Galactic outflows can facilitate this escape by advecting CRs into the IGM. An outflow that results in a termination shock can also generate more CRs. We show that the CR protons from the above processes can significantly affect the thermal history of the IGM. Within plausible range of parameters, cosmic ray heating can compensate for adiabatic cooling and explain the measured IGM temperature at redshifts z between 2 to 4, even with early reionization.

astro-ph↗

arXiv2001

Two Time Correlation For A Noise Driven Double-Well Oscillator In The Suzuki Regime

We study the two time correlation for the noise driven dynamics of the double-well oscillator in the Suzuki regime. It is seen that for very small noise strength the correaltion function shows a lack of translational invariance for very long times characterised by the Suzuki scaling variable. We see that in this strongly out-of-equilibrium situation, the conventional mode-coupling approximation is not a convenient tool.

nlin.AO↗