OJ 287: Discovery of an X-ray and UV flare with Swift
ATel #9629; Dirk Grupe (Morehead State University), S. Komossa (QianNan Normal University for Nationalities), & J. L. Gomez (Instituto de Astrofisica de Andalucia)
on 15 Oct 2016; 12:05 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)
Subjects: Ultra-Violet, X-ray, AGN, Black Hole, Blazar
We report on a very high X-ray and UV flux state in the candidate binary black hole blazar OJ 287 discovered by Swift on October 12. We have monitored OJ 287 before it became sun-constraint for Swift
in June 2016 and found its X-ray 0.3-10 keV flux to be of the order of 6e-15 W/m2. However, when Swift observed OJ 287 on 2016 October 12 (MJD 57673.3568) the X-ray flux in the 0.3-10 keV band was 3.2e-15 W/m2. This is a factor of more than two higher than any value measured of OJ 287 since the beginning of the Swift monitoring campaign in 2015 May. The strong increase in the X-ray flux is accompanied by a softening of the spectrum from about Gamma=2.3+/-0.2 to 2.86+/-0.11 in the most recent observation.
We also noticed an increase of the UV flux by more than a magnitude
compared to the previous values measured before the sun-constraint
in June 2016, and as high as in past observations around December 2015, which were triggered following the optical high-state of the source at that time (ATel #8372, ATel# 8378, Valtonen et al. 2016). The UV magnitudes found in the most recent observation are (not corrected for Galactic reddening):
UVW1: 13.07+/-0.05, UVM2: 13.05+/-0.05, UVW2: 13.25+/-0.05.
We encourage observers to obtain multi-wavelength observations in
order to cover this strong flare.
