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        High-resolution mass models of dwarf galaxies from LITTLE THINGS

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        1502.01281.pdf (PDF, 9Mb)
        Author
        Oh, Se-Heon
        Hunter, Deidre A.
        Brinks, E.
        Elmegreen, Bruce G.
        Schruba, Andreas
        Walter, Fabian
        Rupen, Michael P.
        Young, Lisa M.
        Simpson, Caroline E.
        Johnson, Megan
        Herrmann, Kimberly A.
        Ficut-Vicas, Dana
        Cigan, Phil
        Heesen, V.
        Ashley, Trisha
        Zhang, Hong-Xin
        Attention
        2299/15984
        Abstract
        We present high-resolution rotation curves and mass models of 26 dwarf galaxies from LITTLE THINGS. LITTLE THINGS is a high-resolution Very Large Array HI survey for nearby dwarf galaxies in the local volume within 11 Mpc. The rotation curves of the sample galaxies derived in a homogeneous and consistent manner are combined with Spitzer archival 3.6 micron and ancillary optical U, B, and V images to construct mass models of the galaxies. We decompose the rotation curves in terms of the dynamical contributions by baryons and dark matter halos, and compare the latter with those of dwarf galaxies from THINGS as well as Lambda CDM 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 alpha of their dark matter density profiles. The mean value of the slopes of the 26 LITTLE THINGS dwarf galaxies is alpha =-0.32 +/- 0.24 which is in accordance with the previous results found for low surface brightness galaxies (alpha = -0.2 +/- 0.2) as well as the seven THINGS dwarf galaxies (alpha =-0.29 +/- 0.07). However, this significantly deviates from the cusp-like dark matter distribution predicted by dark-matter-only Lambda CDM simulations. Instead our results are more in line with the shallower slopes found in the Lambda CDM SPH simulations of dwarf galaxies in which the effect of baryonic feedback processes is included. In addition, we discuss the central dark matter 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 Lambda SPH simulations of dwarf galaxies where central cusps still remain.
        Publication date
        2015-06
        Published in
        The Astronomical Journal
        Published version
        https://doi.org/10.1088/0004-6256/149/6/180
        Other links
        http://hdl.handle.net/2299/15984
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