Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Binary Black Holes, Gas Sloshing, and Cold Fronts in the X-ray Halo
  Hosting 4C+37.11   We analyzed deep $Chandra$ ACIS-I exposures of the cluster-scale X-ray halo
surrounding the radio source 4C+37.11. This remarkable system hosts the closest
resolved pair of super-massive black hole and an exceptionally luminous
elliptical galaxy, the likely product of a series of past mergers. We
characterize the halo with $r_{500} = 0.95$ Mpc, $M_{500} = (2.5 \pm 0.2)
\times 10^{14} \ M_{\rm{\odot}}$, $ kT = 4.6\pm 0.2$ keV, and a gas mass of
$M_{\rm g,500} = (2.2 \pm 0.1) \times 10^{13} M_\odot$. The gas mass fraction
within $r_{500}$ is $f_{\rm g} = 0.09 \pm 0.01$. The entropy profile shows
large non-gravitational heating in the central regions. We see several surface
brightness jumps, associated with substantial temperature and density changes,
but approximate pressure equilibrium, implying that these are sloshing
structures driven by a recent merger. A residual intensity image shows core
spiral structure closely matching that seen for the Perseus cluster, although
at $z=0.055$ the spiral pattern is less distinct. We infer the most recent
merger occurred $1-2$ Gyr ago and that the event that brought the two observed
super-massive black holes to the system core is even older. Under that
interpretation, this black hole binary pair has, unusually, remained at
pc-scale separation for more than 2 Gyr.

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The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio