Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mass Deficits, Stalling Radii, and the Merger Histories of Elliptical
  Galaxies   A binary supermassive black hole leaves an imprint on a galactic nucleus in
the form of a "mass deficit," a decrease in the mass of the nucleus due to
ejection of stars by the binary. The magnitude of the mass deficit is in
principle related to the galaxy's merger history, but the relation has never
been quantified. Here, high-accuracy N-body simulations are used to calibrate
this relation. Mass deficits are shown to be approximately 0.5M_{12}, with
M_{12} the total mass of the binary; the coefficient in this relation depends
only weakly on the binary mass ratio or on the galaxy's pre-existing density
profile. Hence, after N mergers, the mass deficit is ~0.5 N M_h with M_h the
final (current) black hole mass. When compared with observed mass deficits,
this result implies between 1 and 3 mergers for most galaxies, in accord with
hierarchical galaxy formation models. Implications for binary stalling radii,
the origin of hyper-velocity stars, and the distribution of dark matter at the
centers of galaxies are discussed.

31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
30
The categories of this paper are: q-alg