Weeks after astronomers released a landmark image of the Milky Way’s supermassive black hole, Sagittarius A*, a separate study showed how it probed the evolution of black holes in dwarf galaxies.
A new analysis of surveys of dwarf galaxies suggests that black holes appear far more frequently in these small galaxies than previously thought. The study team said this study could be a missing link to learn more about the evolution of more massive black holes.
“This result really blew my mind, because these black holes were previously hiding in plain sight,” said lead author Mugdha Polimera, who holds a Ph.D. student at the University of North Carolina-Chapel Hill, said in a statement from the university (opens in a new tab) Tuesday (May 24).
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The Milky Way’s massive Sagittarius A* (Sgr A*) black hole is thought to have formed from gradual mergers of smaller dwarf galaxies over time, much like the Magellanic Clouds that are currently in our view and are heading towards a possible merger.
“Each dwarf that falls may bring with it a central massive black hole, tens or hundreds of thousands of times the mass of our sun, potentially destined to be swallowed up by the Milky Way’s central supermassive black hole,” the author added. ‘university.
Finding the black holes was a major challenge for the study, given that we can only see them through the radiation they produce. Sometimes the high energy we see from growing black holes can look a lot like newborn stars, making it hard to tell which is which in the absence of a detailed spectrum.
The solution the scientists proposed was to use the Sloan Digital Sky Survey’s catalog of emission lines for the entire sky; “Emission lines” refer to the bright lines visible in the spectra of stars. Astronomers focused on a phenomenon known as photoionization, which occurs when an atom becomes electrically charged as radiant energy is absorbed.
The authors used two sets of astronomical records from the catalog that contain large groups of dwarf galaxies, rather than focusing on the largest and brightest galaxies.
By examining the hydrogen and helium that tend to prevail in dwarf galaxies, astronomers compared various elemental combinations and confirmed the work with theoretical simulations. The authors say their tests closely match predictions that dwarf galaxies contain black holes.
A study (opens in a new tab) based on the research was published Tuesday in The Astrophysical Journal.