Detection of the microquasar V404 Cygni at gamma-rays revisited: only one flaring event in quiescence. (arXiv:2006.15790v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Xing_Y/0/1/0/all/0/1">Yi Xing</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Z/0/1/0/all/0/1">Zhongxiang Wang</a>
The microquasar V404 Cygni (also known as GS 2023+338) was previously
reported to have possible GeV gamma-ray emission in two days during its 2015
outburst. In order to provide more detailed information at the high energy
range for this black hole binary system, we conduct detailed analysis to the
data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma Ray
Space Telescope (Fermi). Both LAT database and source catalog used are the
latest. From the analysis, we can not confirm the previous detection. Instead,
we find one possible detection (~4 sigma) of the source at the end of the
outburst in the time period of 2015 Aug. 17-19, and one convincing detection
(~7 sigma) in 2016 Aug. 23-25. The latter shows that the gamma-ray emission of
the source is soft with photon index $Gammasim 2.9$, mostly detected below
~1.3 GeV with Fermi LAT. As gamma-ray emission from microquasars is likely
associated with their jet activity, we discuss the results by comparing with
those well studied cases, namely Cyg X-3 and Cyg X-1. The detection establishes
V404 Cygni as one of four microquasars with detectable gamma-ray emission, and
adds interesting features to the small group, or in a more general context to
X-ray binaries with jets.
The microquasar V404 Cygni (also known as GS 2023+338) was previously
reported to have possible GeV gamma-ray emission in two days during its 2015
outburst. In order to provide more detailed information at the high energy
range for this black hole binary system, we conduct detailed analysis to the
data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma Ray
Space Telescope (Fermi). Both LAT database and source catalog used are the
latest. From the analysis, we can not confirm the previous detection. Instead,
we find one possible detection (~4 sigma) of the source at the end of the
outburst in the time period of 2015 Aug. 17-19, and one convincing detection
(~7 sigma) in 2016 Aug. 23-25. The latter shows that the gamma-ray emission of
the source is soft with photon index $Gammasim 2.9$, mostly detected below
~1.3 GeV with Fermi LAT. As gamma-ray emission from microquasars is likely
associated with their jet activity, we discuss the results by comparing with
those well studied cases, namely Cyg X-3 and Cyg X-1. The detection establishes
V404 Cygni as one of four microquasars with detectable gamma-ray emission, and
adds interesting features to the small group, or in a more general context to
X-ray binaries with jets.
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