The Abell 85 BCG: a nucleated, core-less galaxy

TL;DR

High-resolution imaging of the Abell 85 BCG reveals a nuclear emission and a continuous brightness profile, challenging previous claims of an evacuated core, and is best described by a double Sersic model.

Contribution

This study provides the first high-resolution imaging evidence of nuclear emission in the Abell 85 BCG and refutes the existence of an evacuated core, proposing a double Sersic profile as the best fit.

Findings

Detection of nuclear emission in the galaxy's center

Refutation of the evacuated core hypothesis

Surface brightness profile fits a double Sersic model

Abstract

New high-resolution r band imaging of the brightest cluster galaxy (BCG) in Abell 85 (Holm 15A) was obtained using the Gemini Multi Object Spectrograph. These data were taken with the aim of deriving an accurate surface brightness profile of the BCG of Abell 85, in particular its central region. The new Gemini data show clear evidence of a previously unreported nuclear emission that is evident as a distinct light excess in the central kiloparsec of the surface brightness profile. We find that the light profile is never flat nor does it present a downward trend towards the center of the galaxy. That is, the new Gemini data show a different physical reality from the featureless, "evacuated core" recently claimed for the Abell 85 BCG. After trying different models, we find that the surface brightness profile of the BCG of Abell 85 is best fit by a double Sersic model.