NOAO >   Observing Info >   Approved Programs >   2014A-0256

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Proposal Information for 2014A-0256


PI: Kathleen Eckert, University of North Carolina at Chapel Hill, keckert@physics.unc.edu
Address: Physics Department, Phillips Hall, CB 3255, Chapel Hill, NC 27599-3255, USA

CoI: Ian Dell'Antonio, Brown University
CoI: Sheila J. Kannappan, University of North Carolina at Chapel Hill
CoI: David Stark, University of North Carolina at Chapel Hill
CoI: Ivana Damjanov, Harvard-Smithsonian Center for Astrophysics
CoI: Dara Norman, NOAO
CoI: Elaine Snyder, University of North Carolina at Chapel Hill

Title: The Low Mass End of the Baryonic Mass Function in Two Extreme Environments

Abstract: We propose to make a direct measurement of the galaxy baryonic mass function (BMF) in two distinct, extreme environments: a high mass cluster and a low density filament on the edge of a void. Pairing deep imaging from DECam with ALFALFA 21cm data, we will measure how the slope of the BMF depends on environment at low baryonic masses down to ~$10^8 M_\odot. Previous BMF measurements have yielded discrepant slopes at the low mass end. However, these measurements have relied on flux-limited samples with large completeness corrections and/or indirectly inferred gas masses, hindering analysis of environmentally dependent processes such as gas stripping and cosmic accretion. Our preliminary BMF, using a volume-limited survey complete to ~$10^9.3 M_\odot, shows evidence for a varying faint end slope as a function of halo mass, conflicting with models in which the BMF slope primarily reflects the physics of early-universe reionization. We request deep DECam ugriz imaging to follow up on this result in two extreme high and low halo mass environments with existing ALFALFA 21cm data, allowing us to identify and measure baryonic masses down to 10^8 M_\odot. The resulting data set will enable the first direct, robust test of potential halo mass dependence in the BMF.


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