Swift Detection/Confirmation of the Hard X-ray Source SWIFT J2114.3+8206/S52116+81

ATel #846; A. Falcone (PSU), J. Tueller (NASA/GSFC), C. Markwardt (UMD/NASA/GSFC), M. Ajello (MPE Garching), S. Barthelmy (GSFC), T. Belloni (INAF/OAB), N. Gehrels (GSFC), O. Godet (U Leicester) , D. Grupe (PSU), S. Holland (USRA/NASA/GSFC), J. Kennea (PSU), K. Mukai (USRA/NASA/GSFC), R. Mushotzky (NASA/GSFC), R. Sambruna (NASA/GSFC), G. K. Skinner (CERS)
on 28 Jun 2006; 19:46 UT
Credential Certification: Abe Falcone (afalcone@astro.psu.edu)

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SWIFT J2114.3+8206 has been detected with the Swift/BAT as part of the hard X-ray survey and with the Swift/XRT X-ray telescope during recent follow-up pointed observations. Swift/BAT confirmed SWIFT J2114.3+8206 as a hard X-ray source by detecting it in the 14-195 keV band with a significance of 7.6 sigma using the 9-month survey data. This confirms past hard X-ray detections of this source by XTE Slew Survey (3-20 keV; Revnivtsev et al. 2004) and BeppoSAX/PDS (13-50 keV; Donato et al. 2005). Swift/BAT observations show indications of variability, and the spectrum in the BAT energy band is well fit by an absorbed power law with a spectral index of 1.8+/-0.25, absorption consistent with the Galactic value, and 14-195 keV flux of 4.3e-11 ergs cm^-2 s^-1.

The BAT position was observed by Swift/XRT for a total of 5.1 ks starting on 2006-06-25 at 14:52:38 UT and ending on 2006-06-26 at 00:40:57 UT. The position of the source (SWIFT J211400.5+820447) is RA=21 14 00.50 dec=+82 04 47.1 (J2000) with an error of 3.5". The position of SWIFT J211400.5+820447 is consistent with the ROSAT source 1RXS J211400.0+820447 and with XSS J21128+8216 (aka 2MASX J21140128+8204483, aka S5 2116+81). This source is thought to be a flat spectrum radio quasar at redshift z=0.08 (Donato, Sambruna, Gliozzi 2005, A&A, 433, 1163). No other strong X-ray sources are present within the BAT error circle.

SWIFT J211400.5+820447 is well fit in the 0.3-10.0 keV energy band by an absorbed power law with photon index 1.94+/-0.1 and absorption (9.8+/-2.1)e20 cm^-2 (galactic absorption=7.4e20 cm^-2). The reduced chi2 of the fit was 1.10 (92 dof). The absorbed flux in the XRT band (0.2-10 keV) is (1.97+/-0.07)e-11 ergs cm^-2 s^-1.

In Apr and Oct 1998, BeppoSAX observed the source S5 2116+81 and found an unabsorbed 2-10 keV flux of 1.6e-11 erg cm^-2 s^-1 (photon index 1.72+/-0.05) and 1.2e-11 erg cm^-2 s^-1 (photon index 1.83+/-0.09), respectively (Donato, Sambruna, Gliozzi 2005, A&A, 433, 1163). The average flux during the Swift/XRT observations is consistent with these flux values, and the variability covers a wider range; from 0.7e-11 erg cm^-2 s^-1 to 1.6e-11 erg cm^-2 s^-1 (unabsorbed, 2-10 keV flux). Significant variability was observed by Swift/XRT in the 0.2-2.0 keV band, as well as the 2-10 keV band.

During the Swift/XRT observations, significant variability was observed down to a 5 hour timescale (doubling time). There were hints of shorter timescale variability. The long timescale BAT data shows indications of variability. These observations support the blazar nature of this source. Further multiwavelength observations are encouraged.