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Workshop / Seminar

Physics and Astronomy Colloquium – Dr. Alexie Leauthaud


About the event

The Department of Physics and Astronomy invites you to a colloquium featuring Dr. Alexie Leauthaud, University of California Santa Cruz. Dr. Leauthaud will present her talk, “The Galaxy-Halo Connection from Gravitational Lensing”, via Zoom.

Meet the speaker at 3:30 p.m. – join us in welcoming the speaker and for an informal chat!
Meeting ID: 957 1082 3436
Passcode: PhysAstro

Abstract: I will begin this talk with an overview of galaxy-galaxy lensing and how it informs us about the connection between galaxies and their dark matter halos. I will then present a variety of new results in this field. First, I will discuss the “lensing is low” effect whereby the lensing signal around massive galaxies has a lower amplitude than predicted based on the galaxy auto-correlation function from BOSS. I will present some new updates on this topic and discuss the cosmological implications of this effect. I will further present “Lensing without Borders”, an inter survey collaborative effort to empirically test the accuracy of galaxy-galaxy lensing measurements in current day surveys. I will also present new results suggesting that the light from central galaxies is a much better tracer of halo mass than previously recognized and I will discuss how this effect might be used to improve optical cluster finding algorithms. Finally, I will present the Merian survey: a new program that will use 60 nights on the Blanco telescope and two custom made filters to detect 100,000 dwarf galaxies and measure their halo masses via gravitational lensing.