Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA   We have investigated the orbital phase dependence of the X-ray spectrum of
the High Mass X-ray Binary pulsar GX 301--2. Here we present the results from a
spectral analysis of two sets of observations of GX 301--2 with the Rossi X-ray
Timing Explorer (RXTE). Of particular interest are the variations of the
absorption column density and the iron line flux along with other parameters of
the spectral model with the orbital phase. We found that the X-ray spectrum can
almost always be fitted with a partial covering absorption model. We have
detected enhanced absorption near the periastron. However, the column density
variation with orbital phase is not smooth, as is expected in a smooth stellar
wind model. We discuss the results of the column density variation in the light
of the two proposed models for GX 301-2, an equatorial disk emanating from the
companion star Wray 977 and a gas stream following the neutron star. We also
found that the iron K_alpha and K_beta line fluxes have peaks near the
periastron and are well correlated with the continuum hard X-ray flux. The line
equivalent width shows an interesting pattern with the column density,
reasonably constant for low values of the column density and increasing rapidly
beyond a certain value.

12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc