Discovery of A red quasar with recurrent activity

Abstract

We report a new double–double radio quasar (DDRQ) J0746+4526 which exhibits two cycles of episodic activity. From radio continuum observations at 607 MHz using the Giant Metrewave Radio Telescope and 1400 MHz from the Faint Images of the Radio Sky at Twenty-cm survey we confirm its episodic nature. We examine the Sloan Digital Sky Survey (SDSS) optical spectrum and estimate the black hole mass to be (8.2 ± 0.3)×10⁷ Mꙩ from its observed Mg ii emission line, and the Eddington ratio to be 0.03. The black hole mass is significantly smaller than for the other reported DDRQ, J0935+0204, while the Eddington ratios are comparable. The SDSS spectrum is significantly red-continuum-dominated, suggesting that it is highly obscured with E(B − V )host = 0.70±0.16 mag. This high obscuration further indicates the existence of a large quantity of dust and gas along the line of sight, which may have a key role in triggering the recurrent jet activity in such objects.