Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray Properties of Intermediate-Mass Black Holes in Active Galaxies.
  II. X-ray-Bright Accretion and Possible Evidence for Slim Disks   We present X-ray properties of optically-selected intermediate-mass
(~10^5--10^6 M_Sun) black holes (BHs) in active galaxies (AGNs), using data
from the Chandra X-Ray Observatory. Our observations are a continuation of a
pilot study by Greene & Ho (2007). Of the 8 objects observed, 5 are detected
with X-ray luminosities in the range L_0.5-2 keV = 10^41--10^43 erg s^-1,
consistent with the previously observed sample. Objects with enough counts to
extract a spectrum are well fit by an absorbed power law. We continue to find a
range of soft photon indices 1 < \Gamma_s < 2.7, where N(E) \propto
E^-\Gamma_s, consistent with previous AGN studies, but generally flatter than
other narrow-line Seyfert 1 active nuclei (NLS1s). The soft photon index
correlates strongly with X-ray luminosity and Eddington ratio, but does not
depend on BH mass. There is no justification for the inclusion of any
additional components, such as a soft excess, although this may be a function
of the relative inefficiency of detecting counts above 2 keV in these
relatively shallow observations. As a whole, the X-ray-to-optical spectral
slope \alpha_ox is flatter than in more massive systems, even other NLS1s. Only
X-ray-selected NLS1s with very high Eddington ratios share a similar \alpha_ox.
This is suggestive of a physical change in the accretion structure at low
masses and at very high accretion rates, possibly due to the onset of slim
disks. Although the detailed physical explanation for the X-ray loudness of
these intermediate-mass BHs is not certain, it is very striking that targets
selected on the basis of optical properties should be so distinctly offset in
their broader spectral energy distributions.

20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th