Intra-night optical variability study of a non-jetted narrow-line Seyfert 1 galaxy: SDSS J163401.94+480940.1

Abstract

SDSS J163401.94þ480940.1 is a non-jetted radio-loud narrow-line Seyfert 1 (NLSy1) galaxy. Optical monitoring of this object was carried out in two intra-night sessions each 3 h with 3.6-m DOT. Intra-night optical variability characterization is presented for the first time for this source. We have detected an unexpected remarkable flare in one of two monitoring sessions of SDSS J163401.94þ480940.1, whose rapid brightening phase implied a minute like doubling time of 22 min, thereby approaching the extremely fast minute like variability, observed from FSRQ PKS 1222þ21 at 400 GeV. The detection of a minute-like variability suggests the existence of relativistic jets with a small viewing angle. We briefly discuss the possible mechanisms for the non-detection of relativistic jets in its very long baseline array observations.