Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropic X-ray emission in AGN accretion discs   Straight-forward models of X-ray reflection in the inner region of accretion
discs predict that primary X-ray flux and the flux reflected off the surface of
the disc should vary together, albeit a short light travel time delay. Most of
the observations, however, show that the X-ray flux can vary while the
reflected features remain constant. Here we propose a simple explanation to
this. In all likelihood, the emission of a moderately optically thick magnetic
flare atop an accretion disc is anisotropic. A constant energy release rate in
a flare will appear to produce a variable X-ray flux as the flare rotates with
the accretion disc anchoring the magnetic tube. The reflector, on the other
hand, receives a constant X-ray flux from the flare. Since the reflected
emission is azimuthally symmetric, the observer will see a roughly constant
reflected flux (neglecting relativistic effects). The model does not produce
quasi-periodic oscillations (QPO) if magnetic flux tubes are sheared out faster
than they complete one orbit.

22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con