Increasing X-Ray Brightness of HBL Source 1ES 1727+650
ATel #10054; Bidzina Kapanadze (Abastumani Astrophysical Observatory at Ilia State University)
on 6 Feb 2017; 21:08 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)
The nearby TeV-detected HBL object 1ES 1727+502 (1Zw 187, z=0.055) has been targeted 111 times by X-ray Telescope (XRT) onboard Swift since 2010 April 2. During this monitoring, the 0.3-10 keV count rate varied by a factor of 17.4 (see http://www.swift.psu.edu/monitoring/source.php?source=QSOB1727+502 ) and showed a prolonged X-ray flaring activity during 2015 March - 2016 February, revealed mainly via the Target of Opportunity observations performed in the framework of our request of different urgencies (Request Number 6571, 6606, 6717, 6809, 6927, 7322, 7355, 7379, 7390, 7404, 7430, 7441, 7516, 7565; see Kapanadze et al. 2015, Atel #8224, #7342). In this period, the source showed its highest historical X-ray state corresponding to 4.96+/-0.06 cts/s (on 2015 November 11). In contrast, the Swift observations , based on our last ToOs of a low urgency (Request Number 8757), the source showed its lowest historical 0.3-10 keV state and then showed a slow long-term increase by a factor of 3 as follows:
2015 December 18 0.28+/-0.02 cts/s
2015 December 25 0.34+/-0.02 cts/s
2017 January 1 0.40+/-0.02 cts/s
2017 January 8 0.49+/-0.02 cts/s
2017 January 15 0.57+/-0.02 cts/s
2017 January 22 0.65+/-0.03 cts/s
2017 January 29 0.89+/-0.04 cts/s
2017 February 5 0.95+/-0.04 cts/s
In the framework of one-zone SSC models, an enhanced activity is also expected in the UV-radio and gamma-ray parts of the spectrum, and intensive multiwavelength observations of 1ES 1727+502 are strongly encouraged to study instable processes and emission mechanisms in this source.
XRT is one of the Swift instruments along with Burst Alert Telescope (BAT) and UV/Optical Telescope (UVOT). It is a JET-X Wolter I type telescope, developed jointly by Pennsylvania State University, Brera Astronomical Observatory (OAB) and University of Leicester. Thanks to the unique characteristics, good photon statistics and low background counts of this instrument (in combination with EEV CCD2 detector), we can investigate a flux variability on different time-scales from minutes to years, obtain high-quality spectra for the majority of the observations, derive different spectral parameters, and study their timing behaviour in the 0.3-10 keV range of the electromagnetic spectrum. The Swift Satellite is operated by Pennsylvania State University.
