SDSS J013127.34?032100.1: A NEWLY DISCOVERED RADIO-LOUD QUASAR AT z = 5.18 WITH EXTREMELY HIGH LUMINOSITY

摘要

Very few of the z>5 quasars discovered to date have been radio-loud, with radio-to-optical flux ratios (radioloudness parameters) higher than 10. Here we report the discovery of an optically luminous radio-loud quasar, SDSS J013127.34?032100.1 (J0131?0321 in short), at z = 5.18± 0.01 using the Lijiang 2.4 m and Magellan telescopes. J0131?0321 has a spectral energy distribution consistent with that of radio-loud quasars.With an i-band magnitude of 18.47 and a radio flux density of 33 mJy, its radio-loudness parameter is ～100. The optical and nearinfrared spectra taken by Magellan enable us to estimate its bolometric luminosity to be L_(bol) ～ 1.1 × 10~(48) erg s~(~(?1)), approximately 4.5 times greater than that of the most distant quasar known to date. The black hole mass of J0131?0321 is estimated to be 2.7 × 10~9M_⊙, with an uncertainty up to 0.4 dex. Detailed physical properties of this high-redshift, radio-loud, potentially super-Eddington quasar can be probed in the future with more dedicated and intensive follow-up observations using multi-wavelength facilities.