Abstract Details
| Name: Hamsa Padmanabhan Affiliation: IUCAA, Pune Conference ID: ASI2015_491 Title : Probing the universe : through reionization and later Authors and Co-Authors : R. Srianand, IUCAA, Pune T. Roy Choudhury, NCRA, Pune Alexandre Refregier, ETH, Zurich Abstract Type : Oral Abstract Category : General Relativity and Cosmology Abstract : Recent observations of the ionized near-zones of quasars around redshift 6 have indicated an additional source of heating of the intergalactic medium, which has been claimed to be evidence for the beginning stages of helium reionization occurring at this redshift. I will describe how this effect may be studied with hydrodynamical simulations coupled to a radiative transfer code which we have developed. We find that the heating effect depends on the general equation of state of the IGM at that epoch, with steeper equations of state exhibiting less additional heating. This connects the heating due to helium reionization in the quasar near-zones, with the epoch of hydrogen reionization. The additional heating is also dependent on the initial neutral fraction of helium in the quasar vicinity, which points to constraints on single-step reionization scenarios. The heating effect may be effectively captured beyond the cosmic variance by using the curvature statistics, even if the sample size is half what is presently available. In the post-reionization universe, the 21-cm line of neutral hydrogen (HI) promises a powerful probe of the baryonic and dark matter distribution. I will describe how the combination of current observational and theoretical constraints on the neutral hydrogen density and the bias parameter leads to bounds on the power spectrum of HI intensity fluctuations over redshifts 0 to 4. References: 1. Hamsa Padmanabhan, T. Roy Choudhury, R. Srianand (2014), MNRAS 443, 3761 2. Hamsa Padmanabhan, T. Roy Choudhury, Alexandre Refregier (2014), arXiv:1407.6366 |