Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chandra X-ray Observations of the Neutron Star Merger GW170817: Thermal
  X-Ray Emission From a Kilonova Remnant?   The recent discovery of the neutron star merger and multi-messenger event
GW170817 (also known as kilonova GRB170817A) provides an unprecedented
laboratory in which to study these mysterious objects, as well as an
opportunity to test cutting-edge theories of gravity in the strong field
regime. Before this event, such tests of our understanding of the nature of
gravity were not possible. In this study, we analyze the X-ray observations of
GW170817 obtained with NASA's Chandra X-ray Observatory following the 17 August
2017 detection of the event by the Laser Interferometer Gravitational Wave
Observatory (LIGO). Motivated by understanding the emission mechanism for X-ray
light and the outcome of the merger event, we fit the Chandra data with both
non-thermal (as done previously in the literature) and thermal models. We
specifically explore thermal plasma models that would be expected from a
kilonova remnant (KNR). We reproduced the non-thermal results which were
recently published by Nynka et al. (2018). We also find that thermal
bremsstrahlung emission from hot plasma can account for the X-ray emission from
this source. Furthermore, we consider models allowing for an intrinsic
absorption from the merger event, yielding a softer power-law model photon
index than previously published, or a lower plasma temperature. We also report
on evidence for line emission, or excess above the continuum model, near 1.3
keV and 2.2 keV which sheds new light on the interpretation of the KNR and its
nucleosynthesis products. We discuss the feasibility for the KNR as the origin
for thermal X-ray emission at this stage of the kilonova evolution.

12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics