Kavli Affiliate: Michael McDonald
| First 5 Authors: Laurel White, Michael McDonald, Francesco Ubertosi, Massimo Gaspari, Julie Hlavacek-Larrondo
| Summary:
We present a new 8.5 ks Chandra observation of Abell 1885, obtained as part
of the Cluster Evolution Reference Ensemble At Low-z (CEREAL) survey of ~200
low-z galaxy groups and clusters. These data reveal that Abell 1885 is a strong
cool core, with a central cooling time of 0.43 Gyr, and that the central galaxy
hosts an X-ray luminous point source at its center (L=2.3×10^42 erg/s),
indicative of a rapidly accreting supermassive black hole. In the context of
the larger CEREAL sample, we constrain the fraction of clusters at z~0.15 with
X-ray bright central AGN to be no more than 4.1%. Including radio data from
LOFAR, GMRT, ASKAP, and the VLA and optical integral field unit data from SDSS
MaNGA, we probe the details of cooling, feeding, and feedback in this system.
These data reveal that cooling of the intracluster medium is highly suppressed
on large (>10 kpc) scales despite a central supermassive black hole that is in
the early stages of the self-regulation cycle (characterized by rapid
accretion, physically small jets, and no large-scale low-frequency radio
emission). To reconcile the large-scale quenching with a lack of visible
large-scale feedback, we propose that the timescale on which energy is
dissipated on large scales is significantly longer than the timescale on which
black hole feeding operates on small (~pc) scales. These observations suggest
that there are two separate timescales characterizing AGN feedback in clusters:
the short timescale of small-scale feeding and feedback processes and a longer
timescale by which energy is dissipated on large physical scales in the
intracluster medium. This interpretation disfavors a model in which the energy
is rapidly dissipated (e.g. shocks), which would synchronize the feeding and
feedback timescales, and favors a model in which the heating effects of AGN
feedback can linger long after the outburst has passed (e.g. turbulent mixing).
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