A strong X-ray Flare in 1ES 1959+650
ATel #9121; Bidzina Kapanadze (Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia)
on 6 Jun 2016; 11:59 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)
Subjects: X-ray, AGN, Blazar
Referred to by ATel #: 9139, 9148, 9203, 9239, 9949, 10430, 10514, 10743, 11059, 11538, 15433, 16087, 16162
The nearby TeV-detected HBL object 1ES 1959+650 (z=0.047) has been observed by Swift today which revealed a strong X-ray flare in the source. Namely, the observation-binned 0.3-10 keV count rate is 16.49+/-0.15 cts/s that is by a factor 2.45 larger compared to weighted mean count rate from all Swift-XRT pointings to this source, and by 90% larger than the rate recorded during the previous observation (performed on June 4). Note that the higher brightness states were observed only three times in the past (in 2015 September - December; see Kapanadze B. et al. 2016, "A recent strong X-ray flaring activity of 1ES 1959+650 with possibly less efficient stochastic acceleration", MNRASL, in press). 1ES 1959+650 has been detected by the FACT telecope above the 3 sigma confidence with the TeV flux of at least 1 Crab (Daniela Dorner, private communication; see also http://fact-project.org/monitoring/index.php?y=2016&m=06&d=05&source=7&timebin=3&plot=night ). The daily-binned 0.3-100 GeV flux from the Fermi-LAT observation of 1ES 1959+650 on June 5 shows a detection with about 7.7 sigma significance. Note that the detection of 1ES 1959+650 by LAT above the 3 sigma significance on the daily time scales is a rare event (See Kapanadze et al. 2016; Aliu et al. 2103). The 0.3-100 GeV photon flux is (8.51+/-2.00)\times 10^{-8) ph/cm^2/s that corresponds to a flaring state for this object in the LAT-band. In the framework of one-zone SSC models, an increased activity is also expected in the UV-radio and gamma-ray parts of the spectrum, and intensive multiwavelength observations of 1ES 1959+650 are strongly encouraged to study instable processes and emission mechanisms in this source.