A luminous flare in the lensed quasar J0816+2134 at z~7.4

Ekaterina Koptelova^1*

¹National Central University, Graduate Institute of Astronomy, Taoyuan City, Taiwan

* Presenter:Ekaterina Koptelova, email:koptelova@astro.ncu.edu.tw

The high-redshift quasar J0816+2134 at z~7.4 is the first gravitationally lensed quasar known deep within the reionization epoch. J0816+2134 is also the faintest of the most distant quasars known at z>7, with an intrinsic/unlensed absolute magnitude of M1450 ≈ −23. The observed properties of this low-luminosity quasar represent an interest in studying the early formation phases of quasars and the growth of their central black holes. We present the analysis of the intrinsic/unlensed spectral energy distribution of J0816+2134 measured at different epochs. The multi-epoch spectral energy distribution shows evidence for a significant variation in the flux of the Lyα line simultaneous with the dramatic increase in the flux of the UV continuum by ~3 mag. The extreme UV/ soft X-ray flare, which led to the increase in the flux of the Lyα line and that of the UV continuum, may have also caused the increase in the size of the UV/optical emitting region of J0816+2134 as the flare propagated through its accretion disk. We discuss the change in the mass growth rate of the black hole of J0816+2134 associated with the flare and the role of such changes in the rapid growth of first supermassive black holes.

Keywords: High-Redshift Quasars, Gravitationally Lensed Quasars, Supermassive Black Holes, Spectral Energy Distribution, Formation of Supermassive Black Holes