Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Prompt X-ray emission from Fast Radio Bursts -- Upper limits with
  AstroSat   Fast Radio Bursts (FRBs) are short lived ($\sim$ msec), energetic transients
(having a peak flux density of $\sim$ Jy) with no known prompt emission in
other energy bands. We present results of a search for prompt X-ray emissions
from 41 FRBs using the Cadmium Zinc Telluride Imager (CZTI) on AstroSat which
continuously monitors $\sim70\%$ of the sky. Our searches on various timescales
in the 20-200 keV range, did not yield any counterparts in this hard X-ray
band. We calculate upper limits on hard X-ray flux, in the same energy range
and convert them to upper bounds for $\eta$: the ratio X-ray to radio fluence
of FRBs. We find $\eta \leq 10^{8-10}$ for hard X-ray emission. Our results
will help constrain the theoretical models of FRBs as the models become more
quantitative and nearer, brighter FRBs are discovered.

11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn