Dark Matter Indirect Detection, Gravitational Lensing, and Substructure

The nature of dark matter is one of the largest unsolved astrophysical mysteries. A principal component of the standard model of cosmology, ΛCDM, it constitutes the bulk of structure within the Universe. While its distribution on large scales is well known, on sub-galactic scales these properties are far more poorly constrained. These substructures contain some of the highest densities of dark matter in the Universe, and so are exemplary targets for astrophysical searches - either by indirect detection or gravitational lensing. In this thesis, I investigate methods that utilise the substructure of dark matter in order to constrain the properties of the Universe. Through both gravitational lensing and searches for signatures of dark matter annihilation, I investigate the effect that the presence of dense substructures would have on our astrophysical observations. I discuss the effect that ultracompact substructures would have on pulsar timing. Using archival data, I constrain the abundance of such substructures, and show how these constraints can be applied to the properties of the early Universe. Similarly, as part of the science case of the Theia mission proposal, I explore the effect that substructures would have on the likelihood of microlensing events. In the case that dark matter annihilates, substructures would be strong sources of annihilation products. I investigate the heating of surrounding gas that annihilation products would cause, as well as the effect that substructure would have on the apparent point-like nature of the gamma-ray signal at the Galactic Centre

Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report

This report describes the 2014 study by the Science Definition Team (SDT) of the Wide-Field Infrared Survey Telescope (WFIRST) mission. It is a space observatory that will address the most compelling scientific problems in dark energy, exoplanets and general astrophysics using a 2.4-m telescope with a wide-field infrared instrument and an optical coronagraph. The Astro2010 Decadal Survey recommended a Wide Field Infrared Survey Telescope as its top priority for a new large space mission. As conceived by the decadal survey, WFIRST would carry out a dark energy science program, a microlensing program to determine the demographics of exoplanets, and a general observing program utilizing its ultra wide field. In October 2012, NASA chartered a Science Definition Team (SDT) to produce, in collaboration with the WFIRST Study Office at GSFC and the Program Office at JPL, a Design Reference Mission (DRM) for an implementation of WFIRST using one of the 2.4-m, Hubble-quality telescope assemblies recently made available to NASA. This DRM builds on the work of the earlier WFIRST SDT, reported by Green et al. (2012) and the previous WFIRST-2.4 DRM, reported by Spergel et. (2013). The 2.4-m primary mirror enables a mission with greater sensitivity and higher angular resolution than the 1.3-m and 1.1-m designs considered previously, increasing both the science return of the primary surveys and the capabilities of WFIRST as a Guest Observer facility. The addition of an on-axis coronagraphic instrument to the baseline design enables imaging and spectroscopic studies of planets around nearby stars.Comment: This report describes the 2014 study by the Science Definition Team of the Wide-Field Infrared Survey Telescope mission. 319 pages; corrected a misspelled name in the authors list and a typo in the abstrac