Session Y03: Indirect Constraints on Dark Matter

Live

Indirect searches seek to detect visible particles from the interactions of dark matter, and can probe even very tiny annihilation or decay rates. I will outline the most stringent limits on dark matter properties from such searches, and then discuss the status of several signals that have provoked interest as possible hints to dark matter physics, with a particular focus on the GeV gamma-ray excess in the inner Milky Way.   

Live

Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their weak interactions with matter, and subsequently convert into X-rays in the magnetic fields surrounding the NSs. I will describe a hard X-ray search from 2 - 8 keV for X-rays arising from this emission mechanism from the nearby Magnificent Seven isolated NSs using archival XMM-Newton and Chandra data. This search leads to the strongest limits to-date on the product of the axion-photon and axion-nucleon couplings for axion masses below ~1e−4 eV. Moreover, I will show that an observed excess of hard X-rays from the Magnificent Seven may arise from axions. I will discuss near-term measurements and analyses to help rule out or confirm this possibility, including preliminary results from a search with NuSTAR data for axion-induced X-rays from nearby star clusters.   

Live

There is a substantial effort in the physics community to understand the particle nature of dark matter and to search for, in particular, dark matter interactions with the Standard Model of particle physics. Sizable scattering between dark matter and baryons can lead to significant energy and momentum exchange in the early Universe, altering the evolution of cosmological perturbations. The resulting impact on structure formation enables a broad search for dark matter interactions using cosmological observations in a parameter space that is complementary to that of direct detection experiments. In this talk, I will describe the effect scattering has throughout cosmic history, show current constraints, and discuss the importance of future observations.