Speaker
Dr
Kohei Hayashi
(Institute for Cosmic Ray Research, The University of Tokyo)
Description
The galactic dwarf spheroidal (dSph) galaxies are the promising targets for the dark matter indirect searches for particle dark matter. To place robust constraints on candidate dark matter particles, understanding the dark matter distribution of these systems is of substantial importance.
However, various non-negligible systematic uncertainties complicate the estimate of the J-factors relevant for the dark matter searches in these objects. In particular, the effects of non-sphericity of dark halos and the contamination stars have attracted attention because these are unavoidable uncertainties.
In this study, using the current available kinematic data of the Galactic dSphs, we investigate the effects of them on J-factor estimation simultaneously.
We construct axisymmetric dynamical models combined with new likelihood analysis which takes spatial and velocity distributions of the member and contamination stars into account.
We apply these models to most recent kinematic data for classical and ultra-faint dwarfs and estimate their dark matter distributions and then J-factors. Then we compare our results with previous dynamical analyses based on the assumption of spherical symmetry and conventional elimination methods for contamination.
In this talk, we introduce our constructed combined dynamical analysis and show a comparison of J-factor estimations from our analysis and the previous ones.
In addition, as an intriguing result, we find that some of dSphs favor cusped dark halo rather than cored one even considering a mass-anisotropy degeneracy.
Author
Dr
Kohei Hayashi
(Institute for Cosmic Ray Research, The University of Tokyo)
Co-authors
Dr
Hajime Sugai
(Kavli IPMU, The University of Tokyo)
Dr
Masahiro Ibe
(Institute for Cosmic Ray Research, The University of Tokyo)
Dr
Miho Ishigaki
(Kavli IPMU, The University of Tokyo)
Dr
Shigeki Matsumoto
(Kavli IPMU, The University of Tokyo)
Mr
Shunichi Horigome
(The University of Tokyo)
