Title: New Constraints on the Dark Matter Density Profiles of Dwarf Galaxies from Proper Motions of Globular Cluster Streams

Abstract

The central density profiles in dwarf galaxy halos depend strongly on the nature of dark matter (DM). Recently, in Malhan et al. we employed N-body simulations to show that the cuspy cold DM subhalos predicted by cosmological simulations can be differentiated from cored subhalos using the properties of accreted globular cluster (GC) streams since these GCs experience tidal stripping within their parent halos prior to accretion onto the Milky Way. We previously found that clusters that are accreted within cuspy subhalos produce streams with larger physical widths and higher dispersions in line-of-sight velocity and angular momentum than streams that are accreted within cored subhalos. Here, we use the same suite of simulations to demonstrate that the dispersion in the tangential velocities of streams ($${\sigma }_{{v}_{\mathrm{Tan}}}$$) is also sensitive to the central DM density profiles of their parent dwarfs and GCs that they were accreted from; cuspy subhalos produce streams with larger $${\sigma }_{{v}_{\mathrm{Tan}}}$$ than those accreted inside cored subhalos. Using Gaia EDR3 observations of multiple GC streams we compare their $${\sigma }_{{v}_{\mathrm{Tan}}}$$ values with simulations. The measured $${\sigma }_{{v}_{\mathrm{Tan}}}$$ values are consistent with both an “in situ” origin and with accretion inside cored subhalos of M ~ 10^8–9 M_⊙ (or very low-mass cuspy subhalos of mass ~10⁸M_⊙). Despite the large current uncertainties in $${\sigma }_{{v}_{\mathrm{Tan}}}$$, we find a low probability that any of the progenitor GCs were accreted from cuspy subhalos of M ≳ 10⁹ M_⊙. The uncertainties on Gaia tangential velocity measurements are expected to decrease in future and will allow for stronger constraints on subhalo DM density profiles.

Authors:

Malhan, Khyati  ^[1];

• Search DOE PAGES for author "Malhan, Khyati"
• Search DOE PAGES for ORCID "0000-0002-8318-433X"

Valluri, Monica  ^[2];

• Search DOE PAGES for author "Valluri, Monica"
• Search DOE PAGES for ORCID "0000-0002-6257-2341"

Freese, Katherine  ^[3];

• Search DOE PAGES for author "Freese, Katherine"
• Search DOE PAGES for ORCID "0000-0001-9490-020X"

Ibata, Rodrigo A.  ^[4]

• Search DOE PAGES for author "Ibata, Rodrigo A."
• Search DOE PAGES for ORCID "0000-0002-3292-9709"

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+ Show Author Affiliations

1. Stockholm Univ. (Sweden); Max Planck Institute for Astronomy, Heidelberg (Germany)
2. Univ. of Michigan, Ann Arbor, MI (United States)
3. Stockholm Univ. (Sweden); Univ. of Texas, Austin, TX (United States)
4. Centre National de la Recherche Scientifique (CNRS), Strasbourg (France); Univ. of Strasbourg (France)

Publication Date:

Fri Dec 23 00:00:00 EST 2022

Research Org.:

Univ. of Texas, Austin, TX (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); Swedish Research Council (SRC); National Aeronautics and Space Administration (NASA); European Research Council (ERC)

OSTI Identifier:

1907428

Grant/Contract Number:  

SC0022021; SC007859; 638-2013-8993; 80NSSC20K0509; 834148

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal. Letters

Additional Journal Information:

Journal Volume: 941; Journal Issue: 2; Journal ID: ISSN 2041-8205

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Stellar streams; Surveys; Dark matter; Dwarf galaxies; Milky Way Galaxy; Globular star clusters