Implications of Unstable Particle Ensembles within the Dynamical Dark Matter Framework and Beyond

Brooks Thomas
Lafayette College
Wednesday, October 10, 2018
11:00 am
NS2 1201
In this talk, I explore some of the astrophysical and cosmological implications of unstable particle ensembles --- ensembles of the sort which arise within the Dynamical Dark Matter framework. The properties of such ensembles are tightly constrained. Indeed, their decays can alter of the primordial abundances of light nuclei, give rise to distortions in the CMB-photon spectrum, modify of the ionization history of the universe, and provide additional contributions to the diffuse extra-galactic photon flux. While the bounds that these considerations impose on a single decaying particle species are well established, the corresponding bounds on ensembles of decaying particles are less well understood. Motivated by these considerations, I examine the cosmological constraints on ensembles of late-decaying and show that each of these constraints can be approximated by a set of simple analytic expressions which can be applied generically to almost any such ensemble. I then turn to discuss some of the novel astrophysical signatures to which decaying particle ensembles which satisfy these constraints can give rise. Identifying such signatures is challenging, however, because they often appear as continuum features rather than sharp lines. Nevertheless, there are strategies which can be used to identify and distinguish such ensembles. One of these strategies exploits correlations that arise between different continuum spectral features associated with the same decay process; another involves the identification of an “energy duality" under which a single spectral feature remains invariant.
Arvind Rajaraman