Alladi Ramakrishnan Hall

Unravelling the Mystery of Dark Matter with Black Holes

Anupam Ray

Tata Institute of Fundamental Research

Primordial black holes (PBHs), possibly formed via gravitational
collapse of large density perturbations in the very early universe, are one
of the earliest proposed and viable dark matter (DM) candidates. PBHs can
make up a large or even entirety of DM over a wide range of masses.
Ultralight PBHs in the mass range of 10^{15} - 10^{17} g, emit particles via
Hawking radiation, act as a decaying DM, and can be probed via observations
of those emitted particles in various space as well as ground based
detectors. In this talk, I will discuss how DSNB searches at the
Super-Kamiokande neutrino observatory, measurement of the 511 keV gamma-ray
line by INTEGRAL telescope, observations of low energy Galactic Center
photons by the imminent soft gamma-ray telescope AMEGO, and EDGES
measurement of  the global 21-cm signal can set robust, world-leading
exclusions on the fraction of DM composed of ultralight PBHs. Finally, I
will also discuss a novel formation mechanism of low mass transmuted black
holes which can be a viable non-primordial solution to sub-Chandrasekhar
mass, pointing out several avenues to test the transmuted origin of low mass
black holes.