Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for a 3 x 10^8 solar mass black hole in NGC 7052 from HST
  observations of the nuclear gas disk   We present an HST study of the nuclear region of the E4 radio galaxy NGC
7052, which has a nuclear disk of dust and gas. The WFPC2 was used to obtain B,
V and I broad-band images and an H_alpha+[NII] narrow-band image. The FOS was
used to obtain H_alpha+[NII] spectra along the major axis, using a 0.26 arcsec
diameter circular aperture. The observed rotation velocity of the ionized gas
is V = 155 +/- 17 km/s at r = 0.2 arcsec from the nucleus. The Gaussian
dispersion of the emission lines increases from sigma = 70 km/s at r=1 arcsec,
to sigma = 400 km/s on the nucleus.
  To interpret the gas kinematics we construct axisymmetric models in which the
gas and dust reside in a disk in the equatorial plane of the stellar body. It
is assumed that the gas moves on circular orbits, with an intrinsic velocity
dispersion due to turbulence. The circular velocity is calculated from the
combined gravitational potential of the stars and a possible nuclear black hole
(BH). Models without a BH predict a rotation curve that is shallower than
observed (V_pred = 92 km/s at r = 0.2 arcsec), and are ruled out at > 99%
confidence. Models with a BH of 3.3^{+2.3}_{-1.3} x 10^8 solar masses provide
an acceptable fit.
  NGC 7052 can be added to the list of active galaxies for which HST spectra of
a nuclear gas disk provide evidence for the presence of a central BH. The BH
masses inferred for M87, M84, NGC 6251, NGC 4261 and NGC 7052 span a range of a
factor 10, with NGC 7052 falling on the low end. By contrast, the luminosities
of these galaxies are identical to within 25%. Any relation between BH mass and
luminosity, as suggested by independent arguments, must therefore have a
scatter of at least a factor 10.

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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg