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2/4/16: SO/NOAO Joint Colloquium Series: Yashar Hezaveh, Stanford

Room: 

Title: Detection of a Dark Matter Subhalo with ALMA Observations of Gravitational Lenses

Abstract:
The number of observed low-mass satellites of the Milky Way is about three orders of magnitude lower than what cold dark matter (CDM) simulations predict, an issue that is referred to as the "Missing Satellite Problem".
In this talk, I will discuss ALMA observations of strongly lensed galaxies and show how we can detect low-mass dark matter subhalos in the lensing galaxies by measuring the gravitationally-induced distortions of lensed images of background sources.
By measuring the abundance of dark matter subhalos in the halos of the lensing galaxies we can determine the mass function of the dark matter subhalos (measured using a purely gravitational probe) and compare it with the CDM predictions to resolve this puzzle.
I will present our first detection of a subhalo using ALMA data and show how we can derive constraints on the abundance of subhalos down to ~2e7 M_{\odot} and give a brief overview of our observational campaign.

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