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Too big to be real? No depleted core in Holm 15a

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posted on 2024-07-26, 13:47 authored by Paolo Bonfini, Bililign Dullo, Alister GrahamAlister Graham
Partially depleted cores, as measured by core-Sérsic model 'break radii,' are typically tens to a few hundred parsecs in size. Here we investigate the unusually large (${R}_{gamma prime =0.5}$ = 4.57 kpc) depleted core recently reported for Holm 15A, the brightest cluster galaxy of Abell 85. We model the one-dimensional (1D) light profile, and also the two-dimensional (2D) image (using Galfit-Corsair, a tool for fitting the core-Sérsic model in 2D). We find good agreement between the 1D and 2D analyses, with minor discrepancies attributable to intrinsic ellipticity gradients. We show that a simple Sérsic profile (with a low index n and no depleted core) plus the known outer exponential 'halo' provide a good description of the stellar distribution. We caution that while almost every galaxy light profile will have a radius where the negative logarithmic slope of the intensity profile $gamma prime $ equals 0.5, this alone does not imply the presence of a partially depleted core within this radius.

Funding

Massive black holes in dense star clusters

Australian Research Council

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The hearts of galaxies

Australian Research Council

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PDF (Published version)

ISSN

1538-4357

Journal title

The Astrophysical Journal

Volume

807

Issue

2

Article number

article no. 136

Pagination

9 pp

Publisher

IOP Publishing

Copyright statement

Copyright © 2014 The American Astronomical Society. The published version is reproduced in accordance with the copyright policy of the publisher and can be also be located at http://dx.doi.org/10.1088/0004-637X/807/2/136

Language

eng

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