Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hard X-ray flares and spectral variability in NGC 4395 ULX1   We report the detection of flaring events in NGC 4395 ULX1, a nearby
ultraluminous X-ray source(ULX), for the first time, using recent XMM-NEWTON
observations. The flaring episodes are spectrally harder than the steady
emission periods, resulting in higher fractional variability in the high energy
regime. A thin Keplerian and a slim accretion disk provide the best-fit
continuum for XMM-NEWTON spectra. In all observations, the presence of a broad
Gaussian emission feature around ~0.9 keV suggests a strong wind outflow in
this ULX. The flaring spectra correspond to higher slim disk temperatures due
to higher mass accretion rate under an advection-dominated accretion scenario.
The luminosity-temperature profile in different flux states is consistent with
the theoretical predictions for a slim accretion disk in the case of
super-Eddington accretion onto a stellar-mass compact object. The unperturbed
absorption column and wind outflow line emission during flaring events suggest
that the site of origin of these flares is mainly the advection flow in the
inner region of the accretion disk.

24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org