Fermi-LAT Gamma-ray Detection of Symbiotic Recurrent Nova V3890 Sgr
ATel #13114; S. Buson (Univ. of Wuerzburg; UMBC), P. Jean (IRAP, Toulouse), C. C. Cheung (NRL), on behalf of the Fermi Large Area Telescope Collaboration
on 17 Sep 2019; 22:31 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)
Subjects: Gamma Ray, >GeV, Nova, Transient
Referred to by ATel #: 13185
The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has detected gamma-ray emission from a source positionally consistent with the recent optical outburst of the recurrent nova V3890 Sgr on 2019 Aug 27.870 reported by A. Pereira (see ATel #13047; AAVSO Alert Notice 677), with an observed peak at V-band on 2019 Aug 28.1188 (ATel #13050). This is its third recorded outburst, with previous outbursts reported in 1962 and 1990.
Preliminary analysis using 3-day time bins indicates its first detection (with greater than 4-sigma signficance) during the time interval 2019 Aug 26-29 with a (E >300 MeV) flux of (1.2 +/- 0.4) x 10^-7 photons cm^-2 s^-1 (photon index fixed at 2.2; statistical uncertainties only). The flux slowly declined over the following 12 days to (2.6 +/- 1.7) x 10^-7 photons cm^-2 s^-1 from Sep 7-10. Summing the data from 2019 Aug 23 to Sep 13, the source is significantly detected (>5 sigma). The gamma-ray onset is coincident with the time of the optical peak, within the 3-day time bin adopted in the current analysis. This is similar to the case of the Fermi-LAT detection of a similar symbiotic-like recurrent nova V407 Cyg 2010 (Abdo et al. 2010 Sci 329, 817; ATel #2487) where the gamma-ray onset was observed coincident with the optical peak.
We encourage further multiwavelength observations. Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source, we encourage multi-wavelength observations. For this source the Fermi LAT contact people are S. Buson (sara.buson@gmail.com) and P. Jean (pjean at irap.omp.eu).
The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
