Exploration of a Recently Discovered Luminous Quasar by Astronomers

Using various space telescopes, an international team of astronomers has observed a recently discovered luminous quasar known as SMSS J114447.77-430859.3 or J1144 for short. Results of the Monitoring Campaign, available in the July 2023 issue of Monthly Notices of the Royal Astronomical Societyshed more light on the characteristics of this source.

Quasars, or quasi-stellar objects (QSOs) are active galactic nuclei (AGN) of extremely high luminosity, which emit electromagnetic radiation that can be observed in radio, infrared, visible, ultraviolet, and X-ray waves. They are among the brightest and most distant objects in the known universe, and serve as essential tools for many studies in astrophysics and cosmology. For example, quasars have been used to investigate the large-scale structure of the universe and the era of reionization. It has also improved our understanding of the dynamics of supermassive black holes and the galactic medium.

J1144 was discovered in June 2022 at a redshift of 0.83. Its bolometric luminosity is about 470 quattordelion erg/s, making it the brightest quasar over the last 9 billion years of cosmic history. It is also the most optically bright (unprotected) quasar at a redshift greater than 0.4.

The mass of the black hole in J1144 is estimated to be about 2.6 billion solar masses. This value, combined with the high polometric luminosity, produces an Eddington ratio of 1.4 for this quasar.

A group of astronomers led by Elias Camon of the University of Toulouse, France, made X-ray observations of this quasar using the Spektr-RG, Swift, NuSTAR and XMM-Newton space telescopes. These four space observatories allowed them to gain more insights into J1144’s properties.

The monitoring campaign found that J1144 shows a change in X-rays by a factor of about 10 within a year. Moreover, the results also indicate a shorter time scale fluctuation of ~2.7% within 40 days. According to the study authors, the large X-ray variance is due to intrinsic changes in the X-ray luminosity of the source accompanied by changes in line-of-sight absorption.

Observations indicate that J1144 appears to accumulate at a rate greater than 40% of the Eddington limit. However, astronomers note that if the black hole’s spin is relatively low, its accretion rate can exceed the Eddington limit.

The researchers confirmed that the X-ray and optical properties of J1144 differ from many high-Eddington sources. They hypothesize that this source may be a radio-quiet standard quasar rather than a quasi-stellar object high on Eddington.

The paper’s authors added that deeper X-ray and UV/optical observations of J1144 are needed to draw definitive conclusions about the nature and diversity of this source.

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