Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A long decay of X-ray flux and spectral evolution in the supersoft
  active galactic nucleus GSN 069   GSN 069 is an optically identified very low-mass AGN which shows supersoft
X-ray emission. The source is known to exhibit huge X-ray outburst, with flux
increased by more than a factor of ~240 compared to the quiescence state. We
report its long-term evolution in the X-ray flux and spectral variations over a
time-scale of ~decade, using both new and archival X-ray observations from the
XMM and Swift. The new Swift observations detected the source in its lowest
level of X-ray activity since outburst, a factor of ~4 lower in the 0.2-2 keV
flux than that obtained with the XMM observations nearly 8 years ago. Combining
with the historical X-ray measurements, we find that the X-ray flux is
decreasing slowly. There seemed to be spectral softening associated with the
drop of X-ray flux. In addition, we find evidence for the presence of a weak,
variable hard X-ray component, in addition to the dominant thermal blackbody
emission reported before. The long decay of X-ray flux and spectral evolution,
as well as the supersoft X-ray spectra, suggest that the source could be a
tidal disruption event, though a highly variable AGN cannot be fully ruled out.
Further continued X-ray monitoring would be required to test the TDE
interpretation, through better determining the flux evolution in the decay
phase.

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The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph