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Under the Firelight: Stellar Tracers of the Local Dark Matter Velocity Distribution in the Milky Way

Necib, Lina and Lisanti, Mariangela and Garrison-Kimmel, Shea and Wetzel, Andrew and Sanderson, Robyn and Hopkins, Philip F. and Faucher-Giguère, Claude-André and Kereš, Dušan (2018) Under the Firelight: Stellar Tracers of the Local Dark Matter Velocity Distribution in the Milky Way. . (Unpublished)

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The Gaia era opens new possibilities for discovering the remnants of disrupted satellite galaxies in the Solar neighborhood. If the population of local accreted stars is correlated with the dark matter sourced by the same mergers, one can then map the dark matter distribution directly. Using two cosmological zoom-in hydrodynamic simulations of Milky Way-mass galaxies from the Latte suite of Fire-2 simulations, we find a strong correlation between the velocity distribution of stars and dark matter at the solar circle that were accreted from luminous satellites. This correspondence holds for dark matter that is either relaxed or in kinematic substructure called debris flow, and is consistent between two simulated hosts with different merger histories. The correspondence is more problematic for streams because of possible spatial offsets between the dark matter and stars. We demonstrate how to reconstruct the dark matter velocity distribution from the observed properties of the accreted stellar population by properly accounting for the ratio of stars to dark matter contributed by individual mergers. After demonstrating this method using the Fire-2 simulations, we apply it to the Milky Way and use it to recover the dark matter velocity distribution associated with the recently discovered stellar debris field in the Solar neighborhood. Based on results from Gaia, we estimate that 42^(+26)_(−22)% of the local dark matter that is accreted from luminous mergers is in debris flow.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper ItemSupporting Information
Garrison-Kimmel, Shea0000-0002-4655-8128
Wetzel, Andrew0000-0003-0603-8942
Sanderson, Robyn0000-0003-3939-3297
Hopkins, Philip F.0000-0003-3729-1684
Faucher-Giguère, Claude-André0000-0002-4900-6628
Kereš, Dušan0000-0002-1666-7067
Additional Information:We thank V. Belokurov, E. Kirby, A. Peter, and D. Spergel for useful conversations. This research made use of Astropy (Astropy Collaboration et al. 2013) and IPython (Pérez & Granger 2007). LN is supported by the DOE under Award Number DESC0011632, and the Sherman Fairchild fellowship. ML is supported by the DOE under Award Number DESC0007968 and the Cottrell Scholar Program through the Research Corporation for Science Advancement. Support for SGK was provided by NASA through Einstein Postdoctoral Fellowship grant number PF5-160136 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. AW was supported by NASA through ATP grant 80NSSC18K1097 and grants HST-GO-14734 and HST-AR-15057 from STScI. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grants NNX15AB22G and 17-ATP17-0067, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. Support for PFH, SGK, and RES was provided by an Alfred P. Sloan Research Fellowship, NSF Collaborative Research Grant #1715847 and CAREER grant #1455342, and NASA grants NNX15AT06G, JPL 1589742, 17-ATP17-0214. Numerical calculations were run on the Caltech compute cluster "Wheeler," allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. This work was performed in part at Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611. We used computational resources from the Extreme Science and Engineering Discovery Environment (XSEDE), supported by NSF.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0011632
Sherman Fairchild FoundationUNSPECIFIED
Department of Energy (DOE)DE-SC0007968
Cottrell Scholar of Research CorporationUNSPECIFIED
NASA Einstein FellowshipPF5-160136
Record Number:CaltechAUTHORS:20190206-105621305
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92725
Deposited By: George Porter
Deposited On:08 Feb 2019 15:28
Last Modified:08 Feb 2019 15:28

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