NOAO >   Observing Info >   Approved Programs >   2014A-0321

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Proposal Information for 2014A-0321


PI: Marla Geha, Yale University, marla.geha@yale.edu
Address: Astronomy Department, New Haven, CT 06511, USA

CoI: Ana Bonaca, Yale University
CoI: Kathryn Johnston, Columbia University
CoI: Nitya Kallivayalil, University of Virginia
CoI: Andreas Kupper, Columbia University
CoI: David Nidever, University of Michigan

Title: An Abridged Tail: Mapping the Palomar 5 Tidal Stream with DECam

Abstract: Palomar 5 (Pal 5) is a gravitationally disrupting Milky Way globular cluster exhibiting prominent tidal tails. These tails show tantalizing evidence for stellar density variations. Such features can form when a dark matter subhalo passes through the stream, heating stars and creating density irregularities. However, variations are also a natural consequence of the cluster's dissolution process, with eddies and wakes predicted along the debris tail. At the depth of SDSS, the observed Pal 5 density variations are at the level of stochastic background variations, and cannot yet verify or rule out either scenario. We propose to image the entire Pal 5 system with DECam to gzi=24, two magnitudes fainter than the SDSS limit. Our goal is to create a high significance density map along the entire stream to test the origin of density variations. We will map beyond the SDSS footprint, providing improved constraints on the interaction history of Pal 5 with the Milky Way. The FOV and sensitivity of DECam are well matched to this experiment. The proposed data will yield unique insights into the clumpiness of the Milky Way's dark matter halo, as well the physics of cluster dissolution.


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NOAO >   Observing Info >   Approved Programs >   2014A-0321

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