X-Ray Flare in the Southern TeV-Detected Blazar 1ES 1101-232
ATel #16322; Bidzina Kapanadze (Ilia State University, Tbilisi, Georgia; National Astrophysical Observatory, Abastumani, Georgia)
on 6 Nov 2023; 15:39 UT
Credential Certification: Bidzina Kapanadze (bidzina_kapanadze@iliauni.edu.ge)
The southern TeV-detected ultra-high-frequency peaked BL Lac object (UHBL) 1ES 1101-232 (z=0.186) has been observed 45 times with the Neil Gehrels Swift Observatory since 2005 June 30. The last Swift visit to the source (November 2; performed in the framework of our TOO Request Number 19587) revealed it to be in a X-ray flaring state: the 0.3-10 keV observation of 1.65 ks duration carried out with the X-Ray Telescope (XRT) onboard Swift recorded the count rate of 2.71+/-0.09 cts/s which is equal to the highest historical 0.3-10 keV rates observed on 2005 June 30 and July 13 (within the error range; our measurements). However, the spectrum is significantly harder than those corresponding to the previous highest states. Namely, when fixing the absorption column density to the value of 2.703$\times$10^20 (derived from Willingale et al. 2013), the 0.3-10 keV spectrum from the last Swift-XRT observation of 1ES 1101-232 is well-fit with the logparabolic model, yielding the photon index at 1 keV $a$=1.73+/-0.06, the curvature parameter $b$=0.55+/-0.11 and synchrotron SED peak position E_p=1.76+/-0.21 keV versus versus $a$=1.96(0.04)-2.01(0.02), $b$=0.08(0.04)-0.20(0.08) and E_p=0.87(0.08)-1.26(0.15) from the spectra of the period 2005 June-July. Since the source is in X-ray flaring state and a further brightening may occur, as well as enhanced multiwavelength (MWL) activity is predicted also in other spectral ranges in the framework of one-zone SSC scenario, we strongly encourage intense MWL observations with the space and ground-based instruments.
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.
