3/17/2023 0 Comments Quasar black holes![]() The infalling gas fuels the black hole "engine," triggering outflows and gas turbulence that incites a firestorm of star birth. The result of the merger has been to make Mrk 231 an energetic starburst galaxy with a star-formation rate 100 times greater than that of our Milky Way galaxy. Evidence of a recent merger comes from the host galaxy's asymmetry, and the long tidal tails of young blue stars. The lower-mass black hole is the remnant of a smaller galaxy that merged with Mrk 231. The dynamic duo completes an orbit around each other every 1.2 years. The central black hole is estimated to be 150 million times the mass of our sun, and the companion weighs in at 4 million solar masses. "The structure of our universe, such as those giant galaxies and clusters of galaxies, grows by merging smaller systems into larger ones, and binary black holes are natural consequences of these mergers of galaxies," added co-investigator Xinyu Dai of the University of Oklahoma. "We are extremely excited about this finding because it not only shows the existence of a close binary black hole in Mrk 231, but also paves a new way to systematically search binary black holes via the nature of their ultraviolet light emission," said Youjun Lu of the National Astronomical Observatories of China, Chinese Academy of Sciences. The second, smaller black hole orbits in the inner edge of the accretion disk, and has its own mini-disk with an ultraviolet glow. The best explanation for the observational data, based on dynamical models, is that the center of the disk is carved out by the action of two black holes orbiting each other. This provides observational evidence that the disk has a big donut hole encircling the central black hole. Instead, the ultraviolet glow of the dusty disk abruptly drops off towards the center. If only one black hole were present in the center of the quasar, the whole accretion disk made of surrounding hot gas would glow in ultraviolet rays. Scientists looked at Hubble archival observations of ultraviolet radiation emitted from the center of Mrk 231 to discover what they describe as "extreme and surprising properties." Like a pair of whirling skaters, the black-hole duo generates tremendous amounts of energy that makes the core of the host galaxy outshine the glow of the galaxy's population of billions of stars, which scientists then identify as quasars. The finding suggests that quasars – the brilliant cores of active galaxies – may commonly host two central supermassive black holes that fall into orbit about one another as a result of the merger between two galaxies. The second black hole must have come from a smaller galaxy that merged with Markarian 231 to ignite the quasar about 1 million years ago.Īstronomers using NASA's Hubble Space Telescope have found that Markarian 231 (Mrk 231), the nearest galaxy to Earth that hosts a quasar, is powered by two central black holes furiously whirling about each other. The best explanation for the gap is that two black holes are orbiting each other in a dizzying dance that powers the quasar fireworks. Instead of being pancake shaped, it looks more like it has a big donut hole. The ultraviolet radiation – only measurable by Hubble – revealed evidence for a curious gap in the disk. ![]() So, astronomers did the next best thing, measure all the light from a disk of infalling material around the black hole. Black holes – even supermassive ones – are too compact to be resolved by any present-day telescope. Hubble Space Telescope astronomers set their sights on the nearest quasar to Earth, Markarian 231, located 581 million light-years away. Supermassive black holes, with millions or billions of times the mass of our sun, are the only imaginable powerhouse behind these tsunamis of raw energy. These brilliant cores of active galaxies blaze with the radiance of a hundred billion stars compressed into a region of space not much larger than our solar system. Four Successful Women Behind the Hubble Space Telescope's Achievements. ![]() Characterizing Planets Around Other Stars.Measuring the Universe's Expansion Rate.
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