Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Warped accretion disks and the unification of Active Galactic Nuclei   Orientation of parsec-scale accretion disks in AGN is likely to be nearly
random for different black hole feeding episodes. Since AGN accretion disks are
unstable to self-gravity on parsec scales, star formation in these disks will
create young stellar disks, similar to those recently discovered in our
Galactic Center. The disks blend into the quasi-spherical star cluster
enveloping the AGN on time scales much longer than a likely AGN lifetime.
Therefore, the gravitational potential within the radius of the black hole
influence is at best axi-symmetric rather than spherically symmetric. Here we
show that as a result, a newly formed accretion disk will be warped. For the
simplest case of a potential resulting from a thin stellar ring, we calculate
the disk precession rates, and the time dependent shape. We find that, for a
realistic parameter range, the disk becomes strongly warped in few hundred
orbital times. We suggest that this, and possibly other mechanisms of accretion
disk warping, have a direct relevance to the problem of AGN obscuration, masing
warped accretion disks, narrow Fe K-alpha lines, etc.

21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an