Finding the happy medium of black holes

Understanding what the "seeds" for the largest black holes in the early Universe.


Using data from NASA‘s Chandra X-ray Observatory and other telescopes, scientists have taken major steps in their hunt to find black holes. Through this observation, they want to determine how common black holes are and what their properties teach us about the formation of the first supermassive black holes.

Many studies have suggested that some black holes contain between about tones times the mass of the Sun. Such black holes also known as intermediate-mass black holes, or IMBHs. Their mass places them in between the well-documented and frequently-studied “stellar mass” black holes on one end of the mass scale and the “supermassive black holes” found in the central regions of massive galaxies on the other.

Mar Mezcua of the Institute of Space Sciences in Spain who led one of the studies said, “We may have found that dwarf galaxies are a haven for these missing middleweight black holes. We didn’t just find a handful of IMBHs — we may have found dozens.”

One group of analysts utilized a large campaign called the Chandra COSMOS-Legacy review to study dwarf galaxies, which contain short of what one percent the measure of mass in stars as our Milky Way does. The portrayal of these galaxies was empowered by the rich dataset accessible for the COSMOS field at various wavelengths, including information from NASA and ESA telescopes.

Mezcua’s team identified forty growing black holes in dwarf galaxies. Twelve of them are located at distances more than five billion light years from Earth and the most distant is 10.9 billion light years away, the most distant growing black hole in a dwarf galaxy ever seen. One of the dwarf galaxies is the least massive galaxy found to host a growing black hole in its center.

A large portion of these sources is likely IMBHs with masses that are around ten thousand to a hundred thousand times that of the Sun. One crucial aftereffect of this examination is that the division of cosmic systems containing growing black holes is littler for less monstrous universes than for their more enormous partners.

A second group driven by Igor Chilingarian of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., found a different, vital example of conceivable IMBHs in cosmic systems that are nearer to us. In their example, the most removed IMBH applicant is around 2.8 billion light a very long time from Earth and around 90% of the IMBH competitors they found are close to 1.3 billion light-years away.

Gathering the data from the Sloan Digital Sky Survey (SDSS), Chilingarian and his partners discovered cosmic systems with the optical light mark of growing black holes and after that assessed their mass. They chose 305 galaxies with properties that proposed a black hole with a mass under 300,000 times that of the Sun was lurking in the central regions of every one of these universes.

Only 18 members of this list contained high-quality X-ray observations that would allow confirmation that the sources are black holes. Detections with Chandra and with XMM-Newton were obtained for ten sources, showing that about half of the 305 IMBH candidates are likely to be valid IMBHs. The masses for the ten sources detected with X-ray observations were determined to be between 40,000 and 300,000 times the mass of the Sun.

Chilingarian said, “This is the largest sample of intermediate-mass black holes ever found. “This black hole bounty can be used to address one of the biggest mysteries in astrophysics.”

Mezcua said, “Our evidence is only circumstantial because it’s possible that the IMBHs are just as common in the smaller galaxies but they’re not consuming enough matter to be detected as X-ray sources.”

Chilingarian’s team has a different conclusion,

Ivan Yu. Katkov of Moscow State University in Russia said, “We’re arguing that just the presence of intermediate-mass black holes in the mass range we detected suggests that smaller black holes with masses of about a hundred Suns exist. These smaller black holes could be the seeds for the formation of supermassive black holes.”

Another possibility is that both mechanisms actually occur. Both teams agree that to make firm conclusions much larger samples of black holes are needed using data from future satellites. The paper by Mar Mezcua and colleagues was published in the August issue of the Monthly Notices of the Royal Astronomical Society and is available online. The paper by Igor Chilingarian was recently accepted for publication in The Astrophysical Journal and is available online.

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