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(Left): Illustration of a feeding supermassive black hole. (Right) “Red dots” identified in the region of sky around the quasar J1030. BiRD is a central object: it stands out from the other red dots because it is closer and therefore brighter. | Credits: F. Loiacono, NASA, ESA, CSA
Using the James Webb Space Telescope, astronomers have discovered a monstrous supermassive black hole that existed during the cosmic period known as the “cosmic noon,” which occurred about 4 billion years after the Big Bang. The discovery could further unravel the mystery of how supermassive black holes grow to millions and even billions of times the size of the sun.
This black hole is part of a collection of objects James Webb Space Telescope (JWST) discovered in the early cosmos called “small red dots“, mysterious spots of light that were only discovered recently thanks to the incredibly powerful infrared eye of this $10 billion space telescope. But this black hole has a mass 100 million times that of the sun, so the discovery team named it “BiRD,” which stands for Big Red Dot.
Black holes emit no light themselves, actually trapping any incident light due to their massive gravitational influence, but when these cosmic titans are surrounded by the mass of matter they feed on, this matter and the jets blasted from the poles of black holes create a very bright and vivid object called a quasar. It can be seen from great distances; for example, light from BiRD travels to Earth 10 billion years.
BiRD was observed in the region of the sky around the previously known quasar called J1030+0524 (J1030), the power itself supermassive black hole is about 12.5 billion light-years from Earth. This region of the sky has been well studied by astronomers, including this team from the National Institute of Astrophysics (INAF). But after carefully analyzing the images and spectra obtained with JWST’s Near Infrared Camera (NIRCam), the research team discovered an unusual source of light. A bright infrared spot that has never been revealed by previous X-rays and data.
“Starting with the calibrated images, a catalog of sources in the field was created. It was there that we spotted BiRD: a bright, point-like object that, however, was not a star and did not appear in existing X-ray and radio catalogs,” team leader and INAF research associate Federica Loiacono said in a statement translated from Italian. “I analyzed its spectrum, which tells us about the chemical composition and some of the physical properties of the object.”
This is possible because the elements absorb and emit light at specific and characteristic frequencies. This means that elements leave their “fingerprints” in the wavelengths or spectra of light.
“We found clear signals for hydrogen, in particular a line called Paschen gamma, a luminous signature that reveals the presence of ionized hydrogen, and helium, also visible during absorption,” said Loiacono. “These details allowed us to estimate the distance to BiRD and to see that it is relatively close to us compared to many small red dots known so far. We were also able to estimate the mass of the central black hole from analysis of the spectrum of this source: about 100 million times that of the Sun.”
Small red dots are very compact objects with interesting spectroscopic properties. There are many possible theories regarding these bodies, including a recent proposal that they may be a new class of celestial bodies called “black hole stars.” One prevailing theory is that the tiny red dots feed and grow supermassive black holes. The problem with this concept is that the region around black holes should emit strongly in the X-ray region of the electromagnetic spectrum, but this does not seem to be the case for small red dots or BiRDs.
One possible explanation for this is that the small red dots are the huge “seeds” of black holes from which supermassive black holes grow, so they are still surrounded by thick envelopes of gas and dust that absorb high-energy X-rays and allow low-energy infrared light to pass through.
But even among the known small red dots, BiRD is an odd example.
“Prior to BiRD, only two other small red dots with the same spectral characteristics, including helium lines and Paschen gamma rays, were known at the same cosmic distance,” explained Loiacono. “When we compared the spectral properties of BiRD with the other two, we found strong similarities: the line width, absorption, black hole mass and gas density are very similar. This allowed us to conclude that BiRD belongs to the same family as the small red dots.”
In addition to the discovery of BiRD, this research could change the way scientists think about tiny red dots and, in turn, the growth and evolution of supermassive black holes. It was previously thought that these objects would have started to fade as the cosmic meridian fell about 11 billion years ago. However, this team did a calculation on the abundance of the small red dots at cosmic noon and found that they are still abundant during this cosmic epoch.
“The challenge now is to expand the study to include a larger number of nearby LRDs that we can study in more detail than distant ones to create a more complete picture,” concluded Loiacono. “JWST has opened a new frontier in extragalactic astrophysics, revealing objects we didn’t even suspect existed, and we’re only at the beginning of this adventure.”
The team’s research was published Thursday (October 30) in the journal Astronomy and astrophysics.