S5 2007+777

Description

S5 2007+777 is a blazar that varies across the electromagnetic spectrum, with amplitudes increasing with frequency. It is an Intraday Variable source, showing variations in total and polarized intensity on timescales of 2 to 6 days at centimeter wavelengths. Dereddened B and I-band light curves from 2001 show a smaller amplitude variation of 10%, while observations in 2002 and 2004 reveal minimum-to-maximum variations of 30–40% over 2–4 day periods. Mostly quiescent, an outburst between 1991 and 1992 produced a peak flux of 3.69 Jansky at 14.5 GHz, and a gamma ray flare was detected in February 2016 by a 30 cm telescope at Foligno Observatory. Very Long Baseline Array radio imaging reveals a one-sided core-jet structure, with one component showing proper motion and greater flux density. Very Large Array and Very Long Baseline Interferometry imaging instead show a core-dominated source with a bright radio lobe on the eastern side and a long jet on the western side that terminates without a clear hot spot at 10 arcseconds from the nucleus. This jet exhibits superluminal motion, aligned 24° to the line of sight, with a 4.9 GHz luminosity of 10^32 erg s−1 Hz−1. The radio emission contains several unique knots, the brightest located midstream; at 1.49 GHz the jet has an extended linear structure that bends west at a changed position angle of 20°. An extended X-ray jet on kiloparsec scales was found by Chandra, making S5 2007+777 one of only four BL Lacertae objects with this feature.