Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An X-ray study of the supernova remnant G18.95-1.1   We present an analysis of data from both the Rontgen Satellite (ROSAT), and
the Advanced Satellite for Cosmology and Astrophysics (ASCA) of the supernova
remnant (SNR) G18.95-1.1. We find that the X-ray emission from G18.95-1.1 is
predominantly thermal, heavily absorbed and can be best described by an NEI
(nonequilibrium ionization) model with a temperature around 0.9keV, and an
ionization timescale of 1.1x10^10 /cm3/s. We find only marginal evidence for
non-solar abundances. Comparisons between 21 cm HI absorption data and derived
parameters from our spectral analysis strongly suggest a relatively near-by
remnant (a distance of about 2kpc). Above 4keV, we identify a small region of
emission located at the tip of the central, flat spectrum bar-like feature in
the radio image. We examine two possibilities for this emission region: a
temperature variation within the remnant or a pulsar wind nebula (PWN). The
current data do not allow us to distinguish between these possible
explanations. In the scenario where this high-energy emission region
corresponds to a PWN, our analysis suggests a rotational loss rate for the
unseen pulsar of about 7x10^35 erg/s and a ratio Lr/Lx about 3.6 for the entire
PWN, slightly above the maximum ratio (3.4 for Vela) measured in known PWN.

36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph