Discovery of a hyperluminous quasar at z = 1.62 with Eddington ratio >3 in the eFEDS field confirmed by KOOLS-IFU on Seimei Telescope
Imanishi, Masatoshi; Ueda, Yoshihiro; Toba, Yoshiki; Tanaka, Masayuki; Nagao, Tohru; Ota, Naomi; Wang, Wei-Hao; Yanagawa, Anri; Yamada, Satoshi; Gao, Zhen-Kai; Oki, Aika; Masu, Keito; Dosaka, Itsuki; Kakimoto, Takumi; Kobayashi, Seira; Kurokawa, Neiro; Soga, Sorami; Shibata, Kohei; Takeuchi, Sayaka; Tsujita, Yukana
Japan, Taiwan
Abstract
We report the discovery of a hyperluminous type 1 quasar (eFEDS J082826.9-013911; eFEDS J0828-0139) at $z_{\rm spec} = 1.622$ with a super-Eddington ratio ($\lambda _{\rm Edd}$). We perform the optical spectroscopic observations with KOOLS-IFU (the Kyoto Okayama Optical Low-dispersion Spectrograph with optical fiber) on the Seimei Telescope. The black hole mass ($M_{\rm BH}$) based on the single-epoch method with Mg II$\lambda$2798 is estimated to be $M_{\rm BH} = {(6.2 \pm 1.2) }\times 10^8\, M_{\odot }$. To measure the precise infrared luminosity ($L_{\rm IR}$), we obtain submillimeter data taken by SCUBA-2 on the James Clerk Maxwell Telescope and conduct the spectral energy distribution analysis with X-ray to submillimeter data. We find that $L_{\rm IR}$ of eFEDS J0828-0139 is $L_{\rm IR} = {(6.8 \pm 1.8)} \times 10^{13}\, L_{\odot }$, confirming the existence of a hypeluminous infrared galaxy. $\lambda _{\rm Edd}$ is estimated to be $\lambda _{\rm Edd} = {3.6 \pm 0.7}$, making it a quasar with one of the highest BH mass accretion rates at cosmic noon.