Astronomers have discovered another type of growing supermassive black hole thanks to a suite of telescopes, including NASA’s Chandra X-ray Observatory. The true identity of these black holes helps to solve a long-running mystery in astrophysics.
The wrong black holes are from a survey known as the lunar deep field-south (CDF-S), the deepest X-ray image ever.
Supermassive black holes develop by stretching into surrounding material, which heats up and produces radiation over a wide range of wavelengths, including X-rays. Many astronomers think that this increase involves a phase that occurred billions of years ago, when a dense cocoon of dust and gas covered most black holes. These cocoons of material are fuel sources that enable black holes to grow and produce radiation.
Many black holes submerged in such a cocoon exist (called “highly obscured” black holes) based on the current photograph placed by astronomers. However, this type of growing black hole is extremely difficult to find, and the number of predictions observed so far has been lacking – even in deeper images such as CDF-S.
“With the new identity, we’ve found a bunch of heavily obscure black holes that were previously missed,” said Erini Lambrides of Johns Hopkins University (JHU) in Baltimore, Maryland, who led the study. “We like to say that we found these supermassive black holes, but they were actually there.”
The latest study combined Chandra’s time of over 80 days with the observation of 80 days in the CDF-S with large amounts of data at various wavelengths from other observatories, including NASA’s Hubble Space Telescope and NASA’s Spitzer Space Telescope. The team observed a black hole located 5 billion light years or more away from Earth. At these distances, scientists had already found 67 massive inexplicably rising black holes in both CD-S with both X-rays and infrared data. In this latest study, the authors identified another 28.
These 28 supermassive black holes were previously classified into different categories – either slowly low density or without cocoons, or black holes growing along distant galaxies.
“This wrong black hole can be considered a case of identity,” said Marco Chiaberg, co-author of the Space Telescope Science Institute in Baltimore, Maryland, “but these black holes are actually exceptionally good at hiding what they’re doing Are good. “
Lambrides and his colleagues compared their data with expectations for a specific rising black hole. Using data from all wavelengths except X-rays, they estimated the amount of X-rays to be detected from each black hole. Researchers found the level of X-rays expected from 28 sources to be very low, meaning that the cocoon around them is about ten times more dense than the scientists for these objects.
Considering the high density of cocoons, the team showed that the wrong black holes are producing more X-rays than previously thought, but dense cocoons prevent most of these X-rays from escaping and reaching the lunar telescope is. This means that they are growing more rapidly.
Previous groups did not apply the analysis technique adopted by Lambrides and his team, nor did they use the full set of data available for the CDF-S, giving them little information about the density of cocoons.
These results are important for theoretical models estimating the number of black holes in the universe and their growth rate, including varying amounts of opacity (in other words, how dense their cocoons are). Scientists designed these models to explain the uniform brightness in X-rays in the sky called the “X-ray background”, first discovered in the 1960s. Individual rising black holes seen in images like the CDF-S account for most X-ray backgrounds.
Currently not resolved in different sources, the X-ray background is dominated by X-rays with energy above the threshold that Chandra can detect. Heavily obscured black holes are a natural explanation for this unresolved component because low-energy X-rays are absorbed by the cocoons by high-energy ones, and are therefore less detectable. The additional heavily ambiguous black holes described here help to assimilate past differences between theoretical models and observations.
“It’s like an X-ray backdrop, a blurry picture that’s been slowly gaining attention for decades,” said Roberto Gilli, co-author of the National Institute of Astrophysics (INAF) in Bologna, Italy. “Our work involves understanding the nature of the objects that are to be resolved.”
In addition to helping explain the X-ray background, these results are important for understanding the evolution of supermassive black holes and their host galaxies. The mass of galaxies and their supermassive black holes are interconnected with each other, meaning that the more massive galaxies, the more widely known black holes are.
A paper reporting the results of this study is published in The Astrophysical Journal. Other authors of the paper are Timothy Heckman of JHU; Fabio Vito from Ponticia Università Catalica de Chile in Santiago, Chile; And Colin Norman from JHU.
NASA’s Marshall Space Flight Center manages the lunar program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.
The largest starvation of the largest scale black hole in the universe
A large population of AGN disguised as less luminous AGNs in the Chandra Deep Field South, arxiv.org/abs/2002.00955
Provided by Chandra X-ray Center
Quotes: Black Hole Misidentification Cases (2020, 15 July) Retrieved 15 July 2020 from https://phys.org/news/2020-07-cases-black-hole-mistaken-identity.html
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