An international team of astronomers has reported the discovery of a new hypersolar quasar. The newly discovered quasar, designated eFEDSJ0828-0139, has a high rate of star formation and its black hole is accreting mass at super-Eddington rates. The discovery is detailed in a scientific paper published on the arXiv preprint server on August 16.

Quasars, or quasi-stellar objects (QSOs), are very-high-luminosity active galactic nuclei (AGN) powered by supermassive black holes (SMBHs), and emit electromagnetic radiation observable in the radio, infrared, visible, ultraviolet, and X-ray wavelength ranges. They are among the brightest and most distant objects in the known universe and serve as fundamental tools for numerous studies in astrophysics and cosmology.

Now, a team of astronomers led by Yoshiki Toba of the National Astronomical Observatory of Japan (NAOJ) has discovered a new quasar with a bolometric magnitude greater than 290 quatrodemillion erg/s. The quasar was first identified by the eROSITA instrument on the Spektr-RG spacecraft, and its nature was confirmed by Toba’s team using the Seimei telescope and the James Clerk Maxwell Telescope (JCMT).

“We carried out optical spectroscopic observations with KOOLS-IFU at the Seimei telescope (…) To measure the precise infrared radiance (LIR), we obtained the submillimeter data obtained by SCUBA-2 at JCMT and analyzed the spectral energy distribution using the X-ray submillimeter data range,” explained the researchers.

According to the article, the newly discovered hyperluminous quasar eFEDSJ0828-0139 has a spectroscopic redshift of 1.62. The mass of the SMBH in this quasar is about 620 million solar masses.

The study found that eFEDSJ0828-0139 has a very high infrared luminosity of 68 trillion solar luminosities and an Eddington coefficient of 3.6. This confirms that eFEDSJ0828-0139 is an extremely luminous quasar with a very high black hole mass accretion rate.

The results show that eFEDSJ0828-0139 also has an extremely high star formation rate (SFR), with astronomers estimating the quasar’s SFR to be at least 1,000 solar masses per year.

The authors of the paper summarizing the results noted that eFEDSJ0828-0139 is likely at a certain stage where the SMBH and its host galaxy are actively growing as part of galaxy-SMBH co-evolution.

“As predicted by numerical simulations, we may witness a growth phase of both the SMBH and its host galaxy during galaxy-SMBH co-evolution,” the researchers concluded.

The astronomers added that their discovery proves that many more hyperluminous quasars could be discovered with follow-up observations with next-generation multi-object spectrographs such as the eROSITA all-sky survey and the Subaru Prime Focus Spectrograph (PFS).