Astronomers have identified ID830 as the most X-ray luminous radio-loud quasar known to date, using data from the Spektr-RG spacecraft and multiple ground-based telescopes. This discovery sheds light on the extreme behavior of supermassive black holes (SMBHs) and their surrounding environments.
What Are Quasars?
Quasars, or quasi-stellar objects (QSOs), are incredibly bright active galactic nuclei (AGN) powered by SMBHs at the centers of galaxies. They emit vast amounts of electromagnetic radiation across the spectrum – from radio waves to X-rays – and boast some of the highest luminosities in the universe.
ID830: An Extreme Case
ID830, located at a redshift of 3.43, exhibits a bolometric luminosity of roughly one quindecillion erg/s. This suggests either an exceptionally massive SMBH (potentially approaching the theoretical limit of 10 billion solar masses) or a phase of super-Eddington accretion, where the black hole consumes matter at a rate far exceeding the standard limit.
Multiwavelength Observations Reveal Key Details
A team led by Sakiko Obuchi of Waseda University conducted a comprehensive study of ID830, combining X-ray spectroscopy from eROSITA with optical and ultraviolet data from SDSS and Subaru, alongside radio observations from LOFAR, GMRT, and other facilities. This approach revealed several key characteristics.
Extreme Luminosity and Accretion Rate
The study confirmed that ID830 has an X-ray luminosity of 0.01 quindecillion erg/s, making it one of the brightest X-ray emitting radio-loud quasars ever detected. Its total luminosity was measured at 0.076 quindecillion erg/s, with an Eddington ratio of 1.4, definitively confirming super-Eddington accretion.
Black Hole Mass and Reddening
The SMBH at the center of ID830 is estimated to have a mass of approximately 440 million solar masses. The quasar also exhibits moderate reddening, with a value of 0.39 mag.
High UV-to-X-Ray Ratio
ID830 displays a high ratio of ultraviolet to X-ray luminosity (-1.2), surpassing values observed in other super-Eddington quasars and so-called “little red dots” (LRDs), which are thought to represent early AGNs with rapidly accreting SMBHs.
Jet Power and Host Interaction
The estimated jet kinetic power of ID830, ranging from 1 to 10 quattuordecillion erg/s, is comparable to its radiative luminosity. This suggests that the energy released by the jet efficiently interacts with the surrounding interstellar medium.
A Transitional Phase
The findings suggest that ID830 is currently undergoing a transitional phase, where both the corona and jet are simultaneously energized following an accretion burst. The quasar may represent a post-burst super-Eddington object, bridging the gap between standard quasars and the X-ray weak, rapidly accreting LRDs identified by the James Webb Space Telescope (JWST).
This discovery provides valuable insight into the extreme behavior of SMBHs and the dynamics of accretion processes in the early universe
