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Antlia 2’s Role in Driving the Ripples in the Outer Gas Disk of the Galaxy

Chakrabarti, Sukanya, Chang, Philip, Price-Whelan, Adrian M., Read, Justin, Blitz, Leo and Hernquist, Lars (2019) Antlia 2’s Role in Driving the Ripples in the Outer Gas Disk of the Galaxy The Astrophysical Journal, 886 (1). pp. 67-73.

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Abstract

We employ the earlier published proper motions of the newly discovered Antlia 2 dwarf galaxy derived from Gaia data to calculate its orbital distribution in the cosmologically recent past. Using these observationally motivated orbits, we calculate the effect of the Antlia 2 dwarf galaxy on the outer H I disk of the Milky Way, using both test particle and smoothed particle hydrodynamics simulations. We find that orbits with low pericenters, ∼10 kpc, produce disturbances that match the observed outer H I disk perturbations. We have independently recalculated the proper motion of the Antlia 2 dwarf from Gaia data and found a proper motion of (μ α cosδ, μ δ ) = (−0.068, 0.032) ± (0.023, −0.031) mas yr−1, which agrees with results from Torrealba et al. within the errors, but gives lower mean pericenters, e.g., ∼15 kpc for our fiducial model of the Milky Way. We also show that the Sagittarius dwarf galaxy interaction does not match the observed perturbations in the outer gas disk. Thus, Antlia 2 may be the driver of the observed large perturbations in the outer gas disk of the Galaxy. The current location of the Antlia 2 dwarf galaxy closely matches that predicted by an earlier dynamical analysis of the dwarf galaxy that drove ripples in the outer Galaxy, and, in particular, its orbit is nearly coplanar to the Galactic disk. If the Antlia 2 dwarf galaxy is responsible for the perturbations in the outer Galactic disk, it would have a specific range of proper motions that we predict here; this can be tested soon with Gaia DR-3 and Gaia DR-4 data.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
Chakrabarti, Sukanya
Chang, Philip
Price-Whelan, Adrian M.
Read, Justinj.read@surrey.ac.uk
Blitz, Leo
Hernquist, Lars
Date : 20 September 2019
DOI : 10.3847/1538-4357/ab4659
Uncontrolled Keywords : dwarf galaxy; Milky Way; Dark matter; Cosmology; HI; simulations; Galaxies; Galactic and extragalactic astronomy; Astrophysics - Astrophysics of Galaxies
Depositing User : James Marshall
Date Deposited : 29 Jan 2020 11:19
Last Modified : 29 Jan 2020 11:19
URI: http://epubs.surrey.ac.uk/id/eprint/853470

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