An article published in the journal “Nature Astronomy” reports the results of the study of the dwarf galaxy cataloged as LID-568, which has at its center a supermassive black hole that is devouring materials at a rate that is more than 40 times faster than its theoretical limits. A team of researchers led by astronomer Hyewon Suh of the International Gemini Observatory/NSF NOIRLab combined observations conducted with the Chandra and James Webb space telescopes to obtain precise data on this voracious supermassive black hole. We see it as it was about 1.5 billion years after the Big Bang and its discovery indicates a way in which these very extreme objects manage to grow so quickly.
In recent years, several supermassive black holes have been discovered in the early universe that must have grown very quickly from an astronomical point of view. Scientists struggle to understand the processes of such rapid accretion because it’s difficult to observe the details of galaxies more than ten billion light-years away. LID-568 offers truly intriguing details.
Hyewon Suh’s team used the James Webb Space Telescope to observe a sample of galaxies that are part of the COSMOS survey conducted with NASA’s Chandra X-ray Observatory. This is a survey of galaxies that are very bright in X-rays but invisible at optical and near-infrared frequencies.
The James Webb telescope is more sensitive than other instruments built for infrared astronomy and allowed to detect the emissions of the very ancient dwarf galaxy LID-568 in this band. In particular, the NIRSpec (Near InfraRed Spectrograph) instrument made it possible to obtain a spectrum of the electromagnetic emissions detected for each pixel of the field of view instead of the narrow slice obtained in traditional spectroscopy.
The X-ray detections left many uncertainties about LID-568, but the addition of infrared detections allowed the researchers to obtain a lot of new information about the supermassive black hole at its center. In particular, they were able to detect the powerful outflows of gas around that black hole. This allowed them to understand that a good part of its mass arrived in a single accretion episode. However, that accretion occurred more than 40 times faster than its theoretical limits.
The so-called Eddington limit is related to the maximum luminosity of a black hole and the speed at which it can swallow matter while maintaining a balance between the force of gravity and the outward push generated by the heat of the materials that are falling toward the black hole. The supermassive black hole inside LID-568 was called a super-Eddington because it significantly exceeds that limit.
It’s not yet clear whether the seeds that give birth to supermassive black holes form from the collapse of a primordial star of colossal mass or from the direct collapse of a gas cloud. This study doesn’t provide an answer but indicates that a seed can increase its mass significantly in a single episode. In essence, super-Eddingtons might have been normal when the universe was young but they’re difficult to find.
Perhaps, the stability of a system like a super-Eddington is maintained by powerful outflows like the ones detected in LID-568, which act as a release valve for the excess energy generated by episodes of such fast accretion.
The researchers plan to conduct follow-up observations of the dwarf galaxy LID-568 with the James Webb Space Telescope to further investigate its supermassive black hole’s growth mechanisms. Its mass was estimated to be around 7.2 million times the Sun’s, which is not particularly massive for this type of extreme object, another problem in their study. Webb has once again proved the possibilities it offers astronomers and could allow them to find other super-Eddingtons and provide further information on their fast growth.
