Department of Physics & Astronomy
University of New Mexico

Nuclear, Particle, Astroparticle and Cosmology (NUPAC) Seminars

Seeing the unseen: Using small-scale lensing anisotropies to study dark matter

Presented by Birendra Dhanasingham (UNM)

Strong gravitational lensing provides a promising way to look for clues to the elusive particle nature of dark matter. Indeed, subtle perturbations to lensed images can reveal the dark-matter distribution on sub-galactic scales. In addition to the subhalos of the main lens, a significant contribution to these perturbations comes from dark matter halos along the line-of-sight between the observer and the source. We point out here that these line-of-sight halos imprint a previously unstudied quadrupolar signature in the two-point correlation function of the effective convergence field. This anisotropic signal has the potential to statistically distinguish the line-of-sight halo contribution to lensing perturbations from that of main-lens subhalos in a strongly lensed system, hence significantly improving the constraint on dark matter from strong gravitational lensing. Using Fisher forecasting, we finally show that the current space-based telescopes and future extremely large telescopes have the ability to detect the quadrupole moment due to this unique anisotropic signature.

2:00 pm, Tuesday, May 3, 2022

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