Dr. Anna Nierenberg
University of California Chancellor's Postdoctoral Fellow 


Physics & Astronomy Department
University of California Irvine
Irvine CA 92697-2575

email: anierenb@uci.edu

Revealing the nature of dark matter with strong gravitational lensing
We cannot see dark matter directly, however we can see its gravitational effects. Strong gravitational lenses offer a powerful probe of the nature of dark matter because the multiple strongly lensed images can be warped and magnified by small dark matter halos nearby in projection. The number and masses of these small dark matter halos provides crucial insight into the nature of dark matter.

This is an exciting field as many new gravitational lenses are being discovered in wide field surveys such as DES and PANSTARRS. I am leading two Hubble observing programs (GO-13732, GO-15177) to use WFC3 IR grism imaging of gravitational lenses to measure lensed quasar narrow-line image fluxes.  I am also Co-I on a similar ground based program using the integral field spectrograph OSIRIS on Keck. Unlike optical fluxes, narrow-line fluxes are insensitive to stellar microlensing which is a major contaminant of the dark matter lensing signal (Moustakas and Metcalf 2003). Because narrow-line fluxes are immune to this contaminant, this observing method makes it possible to more than double the number of quasar lenses which can be used to test for the presence of dark matter substructure. We estimate that with a sample of about 20 systems we will be able to rule out alternate Warm Dark Matter models with higher confidence than current limits from the Lyman-α forest.

Related first author papers:

Background image credit: HE0435-1223 ESA/Hubble