Theoretical Physics Colloquium

Milky Way Dark Matter - Melting pot of Astro-and-Particle Physics

by Dr. Subhabrata Majumdar (TIFR. Mumbai)

Tuesday, September 18, 2018 from to (Asia/Kolkata)
at AG 69
Dark Matter (DM) is ubiquitous and of fundamental importance in Cosmology. The realization that our own ‘visible’ Milky Way (MW) is embedded within a ’dark’ halo has been with us for more than half a century. Yet, knowledge of this dark halo is still poor with considerable uncertainty/debate on its size, mass or density structure, etc. Knowledge of the velocities of the DM particles are even poorer and has been largely limited to physically motivated ansatz or extracted out of simulations of ‘MW-like’ galaxies. This lack of knowledge of MW DM impacts our efforts on the direct/indirect detection of DM. For simplicity, experimental DM direct detection exclusion curves in the literature are almost always calculated by assuming a naive Standard Halo Model (SHM) expectation for the MW DM halo. Attempts to incorporate beyond SHM has been, till now, rather naive. 

In this talk, I will discuss our efforts to uncover the phase-space of MW DM with an eye towards DM detection experiments. The right approach is to use an observationally inferred determination, along with the related uncertainties, of the local DM phase-space in a self- consistent manner. In this talk, I will present a detailed look at this fundamentally important element of DM detection results. We will begin with the pure astrophysics of DM tracers and end with re-estimates of the direct detection DM exclusion limits. On the way, I will present the tightest constraint on the local DM density till date and the first ever estimation of the MW DM velocity distribution function from observations.