2015MNRAS.449.1686A -
Mon. Not. R. Astron. Soc., 449, 1686-1690 (2015/May-2)
An updated gamma-ray analysis of the Be-BH binary HD 215227.
ALEXANDER M.J. and McSWAIN M.V.
Abstract (from CDS):
We report an updated analysis of the gamma-ray source AGL J2241+4454 that was detected as a brief two-day flare in 2010 by the AGILE satellite. The high-energy emission of AGL J2241+4454 has been attributed to the binary system HD 215227, which consists of a Be star being orbited by a black hole making it the first known Be-black hole binary system. We have analysed the AGILE data and find a gamma-ray flux of (1.8±0.7)x10–6 ph/ cm2/s, in agreement with the initial report. Additionally, we examined data from the Fermi Large Area Telescope over several time intervals including the two-day flare, the folded orbital phase, and the entire mission ( ∼ 6 yr). We do not detect AGL J2241+4454 over any of these time periods with Fermi and find upper limits of 1.1x10–7 and 5.2x10–10 ph/ cm2/s for the flare and the full mission, respectively. We conclude that the HD 215227 Be-black hole binary is not a true gamma-ray binary as previously speculated. While analysing the Fermi data of the AGL J2241+4454 region, we discovered a previously unknown gamma-ray source with average flux of (13.56±0.02)x10–8 ph/ cm2/s that is highly variable on monthly time-scales. We associate this emission with the known quasar 87GB 215950.2+503417.
Abstract Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
Journal keyword(s):
binaries: general - stars: emission-line, Be - quasars: general - gamma-rays: stars
Simbad objects:
11
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