Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bridging the gap between stellar-mass black holes and ultraluminous
  X-ray sources   The X-ray spectral and timing properties of ultraluminous X-ray sources
(ULXs) have many similarities with the very high state of stellar-mass black
holes (power-law dominated, at accretion rates greater than the Eddington
rate). On the other hand, their cool disk components, large characteristic
inner-disk radii and low characteristic timescales have been interpreted as
evidence of black hole masses ~ 1000 Msun (intermediate-mass black holes). Here
we re-examine the physical interpretation of the cool disk model, in the
context of accretion states of stellar-mass black holes. In particular, XTE
J1550-564 can be considered the missing link between ULXs and stellar-mass
black holes, because it exhibits a high-accretion-rate, low-disk-temperature
state (ultraluminous branch). On the ultraluminous branch, the accretion rate
is positively correlated with the disk truncation radius and the bolometric
disk luminosity, while it is anti-correlated with the peak temperature and the
frequency of quasi-periodic-oscillations. Two prototypical ULXs (NGC1313 X-1
and X-2) also seem to move along that branch. We use a phenomenological model
to show how the different range of spectral and timing parameters found in the
two classes of accreting black holes depends on both their masses and accretion
rates. We suggest that ULXs are consistent with black hole masses ~ 50-100
Msun, moderately inefficiently accreting at ~20 times Eddington.

27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio