Swift follow-up observations of the renewed gamma-ray activity of the quasar S5 0836+710 (4C 71.07) detected by AGILE

ATel #8271; S. Vercellone, P. Romano (INAF/IASF Palermo), C. M. Raiteri (INAF/OA Torino), F. Verrecchia, C. Pittori, F. Lucarelli (ASDC and INAF/OA Roma)
on 11 Nov 2015; 10:08 UT
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Credential Certification: Stefano Vercellone (stefano@ifc.inaf.it)

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On 2015 November 10, following a report of a gamma-ray flare detected by AGILE (Pittori et al., ATel #8266) from the high-redshift (z=2.172) flat-spectrum radio quasar (FSRQ) S5 0836+710 (4C 71.07), we triggered a Swift Target of Opportunity observation.

We report the preliminary results of the Swift observation, starting on 2015-11-10 (MJD 57336.6924).

The XRT/PC spectrum (1976 s), is fitted with an absorbed power law, with two absorbing components (NHGAL=2.8E20 cm-2; Kalberla et al. 2005; and one free NH=0.3E20 cm-2) and a photon index = 1.1+/-0.1. The average unabsorbed flux is 5.6E-11 erg/cm2/s (0.3-10 keV).

The UVOT observed the field simultaneously with the XRT in the following optical and UV filters. The preliminary observed magnitudes in the Vega system are:

MJD Filter Magnitude

57336.7006+/-0.0005 V 16.85+/-0.10 (stat) +/-0.01 (sys)

57336.7247+/-0.0294 B 17.02+/-0.04 (stat) +/-0.02 (sys)

57336.7237+/-0.0294 U 16.24+/-0.04 (stat) +/-0.02 (sys)

57336.7223+/-0.0298 W1 16.88+/-0.06 (stat) +/-0.03 (sys)

57336.7040+/-0.0029 M2 17.32+/-0.07 (stat) +/-0.03 (sys)

57336.7271+/-0.0307 W2 17.65+/-0.06 (stat) +/-0.03 (sys)

The magnitudes are not corrected for Galactic extinction.

Our group has been regularly monitoring S5 0836+710 with Swift since October 2014 in collaboration with the GASP-WEBT. Previously, we triggered Swift ToOs (Vercellone et al., ATel #8229 and ATel #7898) following gamma-ray flares detected by AGILE (Bulgarelli et al., ATel #8223) and Fermi (Ciprini et al., ATel #7870). Based on both the UVOT and XRT data, we note a moderate decrease in flux in the UVOT energy range, while the XRT one is almost consistent with respect to the follow-up of the previous gamma-ray flare.

We warmly thank N. Gehrels, the Science Planners, and the Observatory Duty Scientists for having scheduled these observations.