Detection of the microquasar V404 Cygni at gamma-rays revisited: short flaring events in quiescence. (arXiv:2006.15790v2 [astro-ph.HE] UPDATED)
<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 sub-day time periods during
its 2015 outburst. In order to provide more detailed information at the high
energy range for this black hole binary system, we conduct 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. In
addition to the previously reported detection at the peak of 2015 outburst, we
find possible detection ($sim 4sigma$) of the source during the 3-day time
periods of 2009 May 11–13 and 2015 Aug. 17–19, the latter being at the end of
the 2015 outburst, and one convincing detection ($simeq 7sigma$) in 2016 Aug.
23–25. The high-significance detection shows that the gamma-ray emission of
the source is soft with photon index $Gammasim 2.9$, mostly detected below
$sim 1.3$ GeV with Fermi LAT. As gamma-ray emission from microquasars is
considered to be 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 likely helps identify V404 Cygni as a microquasar with detectable
gamma-ray emission in its quiescent state, and adds interesting features to the
microquasar 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 sub-day time periods during
its 2015 outburst. In order to provide more detailed information at the high
energy range for this black hole binary system, we conduct 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. In
addition to the previously reported detection at the peak of 2015 outburst, we
find possible detection ($sim 4sigma$) of the source during the 3-day time
periods of 2009 May 11–13 and 2015 Aug. 17–19, the latter being at the end of
the 2015 outburst, and one convincing detection ($simeq 7sigma$) in 2016 Aug.
23–25. The high-significance detection shows that the gamma-ray emission of
the source is soft with photon index $Gammasim 2.9$, mostly detected below
$sim 1.3$ GeV with Fermi LAT. As gamma-ray emission from microquasars is
considered to be 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 likely helps identify V404 Cygni as a microquasar with detectable
gamma-ray emission in its quiescent state, and adds interesting features to the
microquasar group, or in a more general context to X-ray binaries with jets.
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