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Dark Matter Distributions in Low-mass Disk Galaxies. I. Hα Observations Using the Palomar Cosmic Web Imager

Relatores, Nicole C. and Newman, Andrew B. and Simon, Joshua D. and Ellis, Richard and Truong, Phuongmai and Blitz, Leo and Bolatto, Alberto and Martin, Christopher and Morrissey, Patrick (2019) Dark Matter Distributions in Low-mass Disk Galaxies. I. Hα Observations Using the Palomar Cosmic Web Imager. Astrophysical Journal, 873 (1). Art. No. 5. ISSN 1538-4357. doi:10.3847/1538-4357/ab0382.

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Dark-matter-only simulations predict that dark matter halos have cusp-like inner density profiles, while observations of low-mass galaxies have found a range of inner slopes that are typically much shallower. It is still not well established whether this discrepancy can be explained by baryonic feedback or if it may require modified dark matter models. To better understand the diversity of dark matter profiles in dwarf galaxies, we undertook a survey of 26 low-mass galaxies (log M*/M⊙ = 8.4-9.8, v_(max) = 50–140 km s^(−1)) within 30 Mpc using the Palomar Cosmic Web Imager, which is among the largest integral field spectroscopic surveys of its type. In this paper, we derive Hα velocity fields for the full sample with a typical spatial resolution of ~160 pc. We extract rotation curves and verify their robustness to several choices in the analysis. We present a method for improving the velocity precision obtained from image slicing spectrographs using narrowband Hα images. For 11 galaxies, we compare the Hα velocity fields to CO kinematics measured using CARMA, finding the maps to be in good agreement. The standard deviation of the difference is typically ~7 km s^(−1), comparable to the level of turbulence in the interstellar medium, showing that the two tracers have substantially the same bulk kinematics. In a companion paper, we will use the rotation curves produced here to construct mass models of the galaxies and determine their dark matter density profiles.

Item Type:Article
Related URLs:
URLURL TypeDescription
Relatores, Nicole C.0000-0002-6041-6388
Newman, Andrew B.0000-0001-7769-8660
Ellis, Richard0000-0001-7782-7071
Truong, Phuongmai0000-0001-9248-6631
Blitz, Leo0000-0002-4272-4432
Bolatto, Alberto0000-0002-5480-5686
Martin, Christopher0000-0002-8650-1644
Morrissey, Patrick0000-0001-8177-1023
Additional Information:© 2019 The American Astronomical Society. Received 2018 December 21; revised 2019 January 22; accepted 2019 January 23; published 2019 February 27. We would like to thank Joshua Adams, Rachel Kuzio de Naray, and Kristine Spekkens for providing the rotation curve data used for comparisons made in Figure 8. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France.
Group:Space Astrophysics Laboratory
Funding AgencyGrant Number
Subject Keywords:dark matter – galaxies: dwarf – galaxies: kinematics and dynamics – galaxies: structure
Issue or Number:1
Record Number:CaltechAUTHORS:20190227-091113228
Persistent URL:
Official Citation:Nicole C. Relatores et al 2019 ApJ 873 5
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93291
Deposited By: Tony Diaz
Deposited On:27 Feb 2019 17:18
Last Modified:16 Nov 2021 16:56

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