Speaker:	Petr Baklanov (ITEP Moscow)
Title:	Type II-P supernovae as primary distance indicators in cosmology
Date (JST):	Thu, Jan 14, 2016, 13:30 - 14:30
Place:	Seminar Room A
Abstract:	I will review briefly primary distance indicators for cosmology, and in particular the Expanding Photosphere Method (EPM) for supernova distance measurements. The EPM allows us to directly determine the distance up to hundreds Megaparsecs and the EPM-distance does not depend on any steps of the cosmological distance ladder. The EPM suggests that the supernova photospheric flux can be expressed via a simple formula involving an important correction factor. The theoretical modelling of SN IIP by Eastman(1996) and Dessart(2005) has revealed the correlation between the correction factor for EPM and the color temperature of a supernova. The best-fit polynomials of the correlation are in qualitative agreement in both papers, however, the values of the correction factor are systematically larger for Dessart approximation, than for Eastman approximation. That is why, the EPM-distance difference can reach up to 50% for the same object! I will discuss the dependence of the correction factor on the parameters of supernovae. Using the self-consistent numerical simulations with our radiation hydrodynamics code STELLA we have obtained diagrams of dependence of the correction factor on the color temperature from the initial phase of explosion up to the nebular stage. Our approach to the numerical simulations differs radically from Dessart methods, nevertheless, at the phase of free expansion our best-fit polynomials are surprisingly close to the ones obtained from Dessart modelling. This result is an additional argument for a ``long'' scale of the EPM-distances. It can be used for direct distance determination to SN IIP using relatively simple measurements.

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