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

Abstract

Partially depleted cores, as measured by core-Sersic model "break radii", are typically tens to a few hundred parsecs in size. Here we investigate the unusually large (cusp radius of 4.57 kpc) depleted core recently reported for Holm 15A, the brightest cluster galaxy of Abell 85. We model the 1D light profile, and also the 2D image (using GALFIT-CORSAIR, a tool for fitting the core-Sersic 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 Sersic 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 equals 0.5, this alone does not imply the presence of a partially depleted core within this radius.

Accepted by ApJ (matches the accepted version)

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• AGN jets and a fanciful trio of black holes in the Abell 85 Brightest Cluster Galaxy