beecee Posted May 10, 2018 Posted May 10, 2018 https://phys.org/news/2018-05-sagittarius-swarm-black-hole-bounty.html Sagittarius A* swarm: Black hole bounty captured in the Milky Way center: Astronomers have discovered evidence for thousands of black holes located near the center of our Milky Way galaxy using data from NASA's Chandra X-ray Observatory. This black hole bounty consists of stellar-mass black holes, which typically weigh between five to 30 times the mass of the Sun. These newly identified black holes were found within three light years—a relatively short distance on cosmic scales—of the supermassive black hole at our Galaxy's center known as Sagittarius A* (Sgr A*). Read more at: https://phys.org/news/2018-05-sagittarius-swarm-black-hole-bounty.html#jCp the paper: https://www.nature.com/articles/nature25029 A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy: Abstract: The existence of a ‘density cusp’1,2—a localized increase in number—of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamics3. The best place to detect such a cusp is in the Galactic Centre, where the nearest supermassive black hole, Sagittarius A*, resides. As many as 20,000 black holes are predicted to settle into the central parsec of the Galaxy as a result of dynamical friction3,4,5; however, so far no density cusp of black holes has been detected. Low-mass X-ray binary systems that contain a stellar-mass black hole are natural tracers of isolated black holes. Here we report observations of a dozen quiescent X-ray binaries in a density cusp within one parsec of Sagittarius A*. The lower-energy emission spectra that we observed in these binaries is distinct from the higher-energy spectra associated with the population of accreting white dwarfs that dominates the central eight parsecs of the Galaxy6. The properties of these X-ray binaries, in particular their spatial distribution and luminosity function, suggest the existence of hundreds of binary systems in the central parsec of the Galaxy and many more isolated black holes. We cannot rule out a contribution to the observed emission from a population (of up to about one-half the number of X-ray binaries) of rotationally powered, millisecond pulsars. The spatial distribution of the binary systems is a relic of their formation history, either in the stellar disk around Sagittarius A* (ref. 7) or through in-fall from globular clusters, and constrains the number density of sources in the modelling of gravitational waves from massive stellar remnants8,9, such as neutron stars and black holes. 2
T. McGrath Posted May 10, 2018 Posted May 10, 2018 (edited) A very interesting read. Thanks for posting it. I come up with three different mass estimates for Sagittarius A* (Sgr A*): 4.1 ± 0.6 × 106M☉ from Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits - The Astrophysical Journal, Volume 689, Number 2, 2008; , from Monitoring Stellar Orbits Around the Massive Black Hole in the Galactic Center - The Astrophysical Journal, Volume 692, Number 2, 2009; and (4.02 ± 0.16 ± 0.04) × 106M ⊙ from An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis - The Astrophysical Journal, Volume 830, Number 1, 2016. I am curious as to how much of those mass estimates include those "nearby" orbiting stellar mass black holes. Edited May 10, 2018 by T. McGrath 1
et pet Posted May 11, 2018 Posted May 11, 2018 ...see : https://www.scienceforums.net/topic/114217-multiple-black-holes-at-the-center-of-our-galaxy/?tab=comments#comment-1046315
beecee Posted May 11, 2018 Author Posted May 11, 2018 24 minutes ago, et pet said: ...see : https://www.scienceforums.net/topic/114217-multiple-black-holes-at-the-center-of-our-galaxy/?tab=comments#comment-1046315 Yes of course etpet I should have given you credit, but at least we are in the right section now.
et pet Posted May 12, 2018 Posted May 12, 2018 2 hours ago, beecee said: Yes of course etpet I should have given you credit, but at least we are in the right section now. I have no idea why you would state that you should have given me credit. I only linked to the previous Thread so that you could be aware of other Members thoughts or insights on this subject that you might to be interested in. You actually participated in that previous Thread. As far as being in "the right section now", that speculative Article that I Linked and Quoted in the Thread that I started had already been moved to this same "section" before you participated in it. So, no ,there was no reason that you should have given me any credit. Any and All credit should go to : Charles J. Hailey, Kaya Mori, Franz E. Bauer, Michael E. Berkowitz, Jaesub Hong and Benjamin J. Hord
beecee Posted May 12, 2018 Author Posted May 12, 2018 1 hour ago, et pet said: I have no idea why you would state that you should have given me credit. So, no ,there was no reason that you should have given me any credit. OK, your wish is my command.
Strange Posted May 12, 2018 Posted May 12, 2018 4 hours ago, beecee said: OK, your wish is my command. “I have no idea why you think my wish should be your command...” 1
beecee Posted May 12, 2018 Author Posted May 12, 2018 1 hour ago, Strange said: “I have no idea why you think my wish should be your command...” Just short circuiting.
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