Searching for Dark Matter with gamma rays and neutron stars

The non-gravitational nature of dark matter (DM) is one of the 
most important open questions in modern physics. In the first half, I 
will discuss how high energy diffuse gamma-ray observations can be used 
to search for DM. PeV scale heavy DM particles can decay to various 
Standard Model final states which in turn can produce high energy gamma 
rays. Using the latest diffuse gamma-ray measurements from LHAASO-KM2A 
and upper limits from Tibet AS_gamma, we put stringent constraints on 
decaying DM for masses 10^6 - 10^9 GeV. In the second half, I will 
discuss a new mechanism in which non-annihilating DM can heat up a cold 
neutron star (NS). Heavy DM particles can get captured, thermalize, 
self-gravitate, and collapse to form a rapidly Hawking-evaporating black 
hole within the NS. Evaporation of this DM-originated black hole can 
heat up a cold NS, which can be observed by telescopes like JWST. Using 
Hawking heating, we obtained sensitivities on DM-nucleon scattering 
cross-sections that are a factor of a few times better than the kinetic 
heating sensitivities for neutron stars for > 10^4 GeV ( > 10^{10} GeV) 
mass of spin-0 (spin-1/2) DM.