A supermassive black hole from the early universe is confounding scientists with behavior that defies established theory. The object, a quasar designated ID830, is not only growing at a rate exceeding known limits for black hole accretion, but also simultaneously emits intense X-rays and radio waves – a combination previously considered improbable.
ID830 is an exceptionally luminous and active quasar, exhibiting powerful bursts of radiation from both its poles. Simultaneously, material spiraling into the black hole generates strong X-ray emissions as it rotates at high velocity. Observations indicate that approximately 12 billion years ago, when the universe was roughly 15 percent of its current age, ID830 had already amassed a mass around 440 million times that of our Sun. This is more than 100 times the mass of Sagittarius A*, the black hole at the center of the Milky Way galaxy.
A study published January 21 in The Astrophysical Journal details how an international team of researchers observed ID830 across multiple wavelengths to understand the mechanisms driving this unusual behavior. The team’s findings challenge existing models of black hole growth and accretion.
Theoretical physics dictates that black hole growth is constrained by a process known as the Eddington limit. This limit arises when the radiation pressure from infalling material counteracts the inward pull of gravity, preventing further accretion. Still, scientists posit that black holes can temporarily surpass this limit during a phase termed “super-Eddington.”
“It should be perfectly possible for a black hole to eat material faster than the Eddington limit for a short period of time before the radiation pressure builds up and limits the accretion rate,” explained Anthony Taylor, an astronomer at the University of Texas at Austin who was not involved in the research.
Researchers calculated ID830’s growth rate by measuring its ultraviolet and X-ray brightness. The results reveal that the quasar is accreting matter approximately 13 times faster than the Eddington limit. One potential explanation is a sudden influx of gas, perhaps triggered by ID830 disrupting and consuming a passing celestial object.
Sakiko Obuchi, an observational astronomer at Waseda University in Tokyo and a co-author of the study, elaborated, “For an SMBH [supermassive black hole] of ID830’s size, this would require not a normal star, but a more massive giant star or a very large gas cloud.” She added that such super-Eddington phases are estimated to last only around 300 years.
Adding to the puzzle is the simultaneous presence of radio and X-ray emissions. This combination is considered atypical, as the super-Eddington accretion process is generally thought to suppress the emergence of these emissions. Researchers suggest this indicates the presence of physical mechanisms not yet fully understood within current models of jet formation and extreme accretion.
The behavior of ID830 represents a rare transitional phase where a black hole is undergoing an exceptionally intense “feeding frenzy.” The immense energy released not only accelerates its growth but also has the potential to impact the surrounding galactic environment by heating and dispersing interstellar gas, potentially inhibiting latest star formation.
These findings offer crucial insights into how supermassive black holes could have grown so rapidly in the early universe and how they, in turn, shaped the evolution of the galaxies they inhabit.