Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Massive Pulsars and Ultraluminous X-ray Sources   The detection of 1.37$\, $s pulsations from NuSTAR J095551+6940.8 implies the
existence of an accreting pulsar, which challenges the conventional
understanding of ultraluminous X-ray source. This kind of sources are proposed
to be massive pulsars in this paper. Considering the general relativistic
effect, stronger gravity of massive pulsars could lead to a larger maximum
luminosity, scaled as the Eddington luminosity. The pseudo-Newtonian potential
is employed to simulate the gravitational field in general relativity, and the
Eddington luminosity is calculated for self-bound stars (quark star and
quark-cluster star) and for the Tolman IV solution. It is found that, for a
massive pulsar with radius close to the Schwarszchild radius, the Eddington
luminosity could be as high as $2\times10^{39} \, {\rm erg\, s}^{-1}$. It is
able to account for the X-ray luminosity of NuSTAR J095551+6940.8 with
reasonable beaming factor. It is also suggested that massive pulsar-like
compact stars could form via this super-Eddington phase of ultraluminous X-ray
source.

15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom