High-resolution mass models of dwarf galaxies from LITTLE THINGS

Journal Article · Mon Jun 01 00:00:00 EDT 2015 · The Astronomical Journal (Online)

DOI:https://doi.org/10.1088/0004-6256/149/6/180· OSTI ID:22879388

Oh, Se-Heon ^[1]; Hunter, Deidre A. ^[2]; Brinks, Elias; Ficut-Vicas, Dana ^[3]; Elmegreen, Bruce G. ^[4]; Schruba, Andreas ^[5]; Walter, Fabian ^[6]; Rupen, Michael P. ^[7]; Young, Lisa M.; Cigan, Phil ^[8]; Simpson, Caroline E. ^[9]; Johnson, Megan C. ^[10]; Herrmann, Kimberly A. ^[11]; Heesen, Volker ^[12]; Ashley, Trisha ^[13]; Zhang, Hong-Xin ^[14]

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1. The International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia)
2. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
3. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom)
4. IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States)
5. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)
6. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
7. National Radio Astronomy Observatory, 1003 Lopezville Road, Socorro, NM 87801 (United States)
8. Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States)
9. Department of Physics, Florida International University, CP 204, 11200 SW 8th St, Miami, FL 33199 (United States)
10. Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia)
11. Department of Physics, Pennsylvania State University Mont Alto, Science Technology Building, Mont Alto, PA 17237 (United States)
12. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
13. Bay Area Environmental Research Institute, Petaluma, CA 94952 (United States)
14. Peking University, Astronomy Department, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China)

We present high-resolution rotation curves and mass models of 26 dwarf galaxies from “Local Irregulars That Trace Luminosity Extremes, The H i Nearby Galaxy Survey” (LITTLE THINGS). LITTLE THINGS is a high-resolution (∼6″ angular; <2.6 km s{sup −1} velocity resolution) Very Large Array H i survey for nearby dwarf galaxies in the local volume within 11 Mpc. The high-resolution H i observations enable us to derive reliable rotation curves of the sample galaxies in a homogeneous and consistent manner. The rotation curves are then combined with Spitzer archival 3.6 μm and ancillary optical U, B, and V images to construct mass models of the galaxies. This high quality multi-wavelength data set significantly reduces observational uncertainties and thus allows us to examine the mass distribution in the galaxies in detail. We decompose the rotation curves in terms of the dynamical contributions by baryons and dark matter (DM) halos, and compare the latter with those of dwarf galaxies from THINGS as well as ΛCDM Smoothed Particle Hydrodynamic (SPH) simulations in which the effect of baryonic feedback processes is included. Being generally consistent with THINGS and simulated dwarf galaxies, most of the LITTLE THINGS sample galaxies show a linear increase of the rotation curve in their inner regions, which gives shallower logarithmic inner slopes α of their DM density profiles. The mean value of the slopes of the 26 LITTLE THINGS dwarf galaxies is α=−0.32±0.24 which is in accordance with the previous results found for low surface brightness galaxies (α=−0.2±0.2) as well as the seven THINGS dwarf galaxies (α=−0.29±0.07). However, this significantly deviates from the cusp-like DM distribution predicted by DM-only ΛCDM simulations. Instead our results are more in line with the shallower slopes found in the ΛCDM SPH simulations of dwarf galaxies in which the effect of baryonic feedback processes is included. In addition, we discuss the central DM distribution of DDO 210 whose stellar mass is relatively low in our sample to examine the scenario of inefficient supernova feedback in low mass dwarf galaxies predicted from recent ΛCDM SPH simulations of dwarf galaxies where central cusps still remain.

• OSTI ID: 22879388
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 6 Vol. 149; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BARYONS
CUSPED GEOMETRIES
FEEDBACK
GALAXIES
HYDRODYNAMICS
IMAGES
LUMINOSITY
MASS
MASS DISTRIBUTION
NONLUMINOUS MATTER
SIMULATION
WAVELENGTHS