We have found that the brightest cluster galaxy (BCG) in Abell~85, Holm 15A,
displays the largest core so far known. Its cusp radius, rγ=4.57±0.06 kpc (4.26′′±0.06′′), is more than 18 times
larger than the mean for BCGs, and ≥1 kpc larger than A2261-BCG, hitherto
the largest-cored BCG (Postman, Lauer, Donahue, et al. 2012) Holm 15A hosts the
luminous amorphous radio source 0039-095B and has the optical signature of a
LINER. Scaling laws indicate that this core could host a supermassive black
hole (SMBH) of mass M∙∼(109−1011)M⊙. We
suggest that cores this large represent a relatively short phase in the
evolution of BCGs, whereas the masses of their associated SBMH might be set by
initial conditions.Comment: 14 pages, 3 figure, 2 tables, accepted for publication in ApJ Letters
on October 6th, 2014, replacement of previous manuscript submitted on May
30th, 2014 to astro-p