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Date and Time of the Query: 2019-05-25 T19:08:05 PDT
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For refcode 2015ApJ...798...55D:
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2015ApJ...798...55D Core Shapes and Orientations of Core-Sersic Galaxies Dullo, Bililign T.; Graham, Alister W. Abstract. The inner and outer shapes and orientations of core-Sersic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sersic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sersic break radii R_b_ ---a measure of the size of their partially depleted core---that are >~ 0."2, we find that the ellipticities and position angles are quite robust against HST seeing. For the bulk of the galaxies, there is a good agreement between the ellipticities and position angles at the break radii and the average outer ellipticities and position angles determined over R_e_/2 < R < R_e_, where R_e_ is the spheroids' effective half light radius. However there are some interesting differences. We find a median "inner" ellipticity at R_b_ of epsilon_med_ = 0.13 +/- 0.01, rounder than the median ellipticity of the "outer" regions epsilon_med_ = 0.20 +/- 0.01, which is thought to reflect the influence of the central supermassive black hole at small radii. In addition, for the first time we find a trend, albeit weak (2sigma significance), such that galaxies with larger (stellar deficit-to-supermassive black hole) mass ratios---thought to be a measure of the number of major dry merger events---tend to have rounder inner and outer isophotes, suggesting a connection between the galaxy shapes and their merger histories. We show that this finding is not simply reflecting the well known result that more luminous galaxies are rounder, but it is no doubt related. Key words: galaxies: elliptical and lenticular, cD, galaxies: fundamental parameters, galaxies: nuclei, galaxies: photometry, galaxies: structure
Retrieve 24 NED objects in this reference.
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