et pet Posted April 5, 2018 Posted April 5, 2018 I came across this, recently published in Nature : https://www.nature.com/articles/nature25029 " A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy " by Charles J. Hailey, Kaya Mori, Franz E. Bauer, Michael E. Berkowitz, Jaesub Hong & Benjamin J. Hord Partial Quote of the Editorial Summary : "Many black holes in the Galactic Centre Simulations predict that the supermassive black holes near the centres of all large galaxies are surrounded by a concentration of stellar-mass black holes. Such black holes, however, have not previously been detected at the centre of our galaxy. Low-mass X-ray binary systems containing black holes are proxies for single black holes. Charles Hailey and collaborators report finding a dozen such binary systems in the central parsec of the Milky Way. " https://www.nature.com/articles/nature25029 References to and Articles about the Letter have been Published @ : https://news.nationalgeographic.com/2018/04/black-hole-stellar-binary-stars-milky-way-galaxy/ - " Thousands of Black Holes May Lurk at the Galaxy's Center The discovery could help scientists better understand the space-time ripples called gravitational waves. By Sarah Gibbens PUBLISHED APRIL 4, 2018 A gaggle of black holes has been found clustered around the center of our home galaxy, the Milky Way—and the discovery hints at a much larger population of black holes hidden across the galaxy. The discover offers a new test bed for understanding the ripples in space-time known as gravitational waves. For years, scientists have known that a monster black hole sits in the middle of the galaxy. Called Sagittarius A* (Sgr A*), the compact object is more than four million times as massive as our sun, but it's packed into a region of space no bigger than the distance between Earth and our star. Scientists had long suspected that as many as 20,000 smaller black holes were orbiting the galactic center. But as the name suggests, black holes are not easy to see directly. (Find out how astronomers are trying to take the first picture of a black hole.) " https://news.nationalgeographic.com/2018/04/black-hole-stellar-binary-stars-milky-way-galaxy/ and @ https://www.newscientist.com/article/2165505-the-centre-of-our-galaxy-may-be-swarming-with-10000-black-holes/ - DAILY NEWS 4 April 2018 " The centre of our galaxy may be swarming with 10,000 black holes By Adam Mann As many as 10,000 new black holes have been discovered buzzing around in the centre of the Milky Way galaxy. The galactic centre is already known to teem with stars, supernovae, pulsars, gas and dust, and the humongous black hole called Sagittarius A*, whose mass is equivalent to four million suns. Simulations have long suggested that many smaller black holes – those with masses around the same as our sun – also exist in the Milky Way’s centre and the middles of other galaxies, though only a single one has ever been spotted. Combing through archival data from NASA’s Chandra X-ray Observatory, Charles Hailey at Columbia University in New York and his colleagues were able to finally tease out a signal that appears to be coming from 12 stellar-mass black holes that have sun-sized stars orbiting them. " https://www.newscientist.com/article/2165505-the-centre-of-our-galaxy-may-be-swarming-with-10000-black-holes/ I found the nature article and subsequent Science site articles very interesting on many levels, to say the least. 2
Strange Posted April 5, 2018 Posted April 5, 2018 (edited) I saw this too. Very interesting. I was going to post about it but you beat me to it! Edited April 5, 2018 by Strange
et pet Posted April 5, 2018 Author Posted April 5, 2018 46 minutes ago, Strange said: I saw this too. Very interesting. I was going to post about it but you beat me to it! Sorry for beating you "to it". If you want, you are more than welcome to have my "Post" deleted. Again, sorry. 1 minute ago, swansont said: ! Moderator Note Moved to Science News Okay, ? I had just replied to "Strange" that my Post could be deleted. It appears that it was done before I could actually hit "Submit Reply". In the future, I will try to make it a point not to Post anything for at least a month or so after reading. Again, sorry to Post Speculative or Theoretical articles on your Site. -1
Strange Posted April 5, 2018 Posted April 5, 2018 28 minutes ago, et pet said: Sorry for beating you "to it". If you want, you are more than welcome to have my "Post" deleted. Nothing to apologise for and no reason to have the post deleted. It is an interesting news story. 28 minutes ago, et pet said: Again, sorry to Post Speculative or Theoretical articles on your Site. There is nothing speculative in this post. (Which is why it has been moved to Science News. Because it is news. About science.)
geordief Posted April 5, 2018 Posted April 5, 2018 43 minutes ago, Strange said: Nothing to apologise for and no reason to have the post deleted. It is an interesting news story. There is nothing speculative in this post. (Which is why it has been moved to Science News. Because it is news. About science.) An amazing story ,even if it was predicted. Has a feel of Tolkein about it.
swansont Posted April 5, 2018 Posted April 5, 2018 2 hours ago, et pet said: Okay, ? I had just replied to "Strange" that my Post could be deleted. It appears that it was done before I could actually hit "Submit Reply". In the future, I will try to make it a point not to Post anything for at least a month or so after reading. Again, sorry to Post Speculative or Theoretical articles on your Site. Not a problem — articles from Nature, Nat Geo and New Scientist are not speculative. They belong in Science News, that's all.
et pet Posted April 5, 2018 Author Posted April 5, 2018 (edited) 1 hour ago, Strange said: Nothing to apologise for and no reason to have the post deleted. It is an interesting news story. There is nothing speculative in this post. (Which is why it has been moved to Science News. Because it is news. About science.) 1.) Please excuse my naivete in the Rules or Proper Conduct in Posting on your site. I have only been a member of a Guitar Forum before - so it seems that I have much to learn about this site. Many people might see what is claimed to be an "Original 1959 Gibson Les Paul" guitar - but until that Guitar can be "Professionally Authenticated" as "Real" - any claim about what it actually is remains purely "Speculative". 2.) I could only Link to the "Abstract" of the Letter on nature.com, : https://www.nature.com/articles/nature25029 , it will be up to each individual reading that "Abstract" to do further study. That being said, it clearly states in the "Abstract" - I added the "Bolding(?)" : " 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. " https://www.nature.com/articles/nature25029 and from the Editorial Summary @ that same Link : https://www.nature.com/articles/nature25029 " Many black holes in the Galactic Centre Simulations predict that the supermassive black holes near the centres of all large galaxies are surrounded by a concentration of stellar-mass black holes. Such black holes, however, have not previously been detected at the centre of our galaxy. Low-mass X-ray binary systems containing black holes are proxies for single black holes. Charles Hailey and collaborators report finding a dozen such binary systems in the central parsec of the Milky Way. By extrapolating these observations they conclude that the total population of such binary systems in the central parsec of the Galaxy is in the hundreds, with a much greater number of isolated black holes. They cannot, however, rule out the contribution of a sub-dominant population of rotating neutron stars that have become millisecond pulsars through the accretion of gas from close companion stars " https://www.nature.com/articles/nature25029 3.) again, sorry, but since this claimed "Original 1959 Gibson Les Paul" (Analogous!) has yet to be "Authenticated", I was under the evidently mistaken idea that it should be considered "Speculative". Edited April 5, 2018 by et pet Grammar ?
Strange Posted April 5, 2018 Posted April 5, 2018 20 minutes ago, et pet said: 3.) again, sorry, but since this claimed "Original 1959 Gibson Les Paul" (Analogous!) has yet to be "Authenticated", I was under the evidently mistaken idea that it should be considered "Speculative". No need to apologise. The "Speculations" section of the forum is for people to present their own "personal" theories for an informal review and feedback. (99.9% of the time it is full of nonsense.) If you are not actively advocating a speculative theory or hypothesis it is OK to post it in the appropriate part of the forum (New, Physics, etc) for discussion.
beecee Posted April 5, 2018 Posted April 5, 2018 30 minutes ago, et pet said: They cannot, however, rule out the contribution of a sub-dominant population of rotating neutron stars that have become millisecond pulsars through the accretion of gas from close companion stars " https://www.nature.com/articles/nature25029 3.) again, sorry, but since this claimed "Original 1959 Gibson Les Paul" (Analogous!) has yet to be "Authenticated", I was under the evidently mistaken idea that it should be considered "Speculative". Science is a discipline in continued progress. As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted. The interpretations are obviously from credentialed professional cosmologists and scientists in general, through the proper channels and via the scientific methodology. That is far removed from adhoc, unevidenced and unprofessional ideas and claims from any Joe Blow with access to a public forum. Nice article...thanks. 17 minutes ago, Strange said: No need to apologise. The "Speculations" section of the forum is for people to present their own "personal" theories for an informal review and feedback. (99.9% of the time it is full of nonsense.) So far on my times on science forums, that 99.9% is far closer to 100% in actual fact. But your point is well made. 1
et pet Posted April 6, 2018 Author Posted April 6, 2018 (edited) 19 hours ago, beecee said: 19 hours ago, beecee said: Science is a discipline in continued progress. As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted. The interpretations are obviously from credentialed professional cosmologists and scientists in general, through the proper channels and via the scientific methodology. That is far removed from adhoc, unevidenced and unprofessional ideas and claims from any Joe Blow with access to a public forum. Nice article...thanks. So far on my times on science forums, that 99.9% is far closer to 100% in actual fact. But your point is well made. 1.) is it because I am new to this site that I cannot read the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted." In my Browser, I can only Read Three(3) Posts from "Strange" : 1.) says "I saw this too. Very interesting. I was going to post about it but you beat me to it!" ; 2.) says "Nothing to apologise for and no reason to have the post deleted. It is an interesting news story." and "There is nothing speculative in this post. (Which is why it has been moved to Science News. Because it is news. About science.)" ; 3.) says "No need to apologise. The "Speculations" section of the forum is for people to present their own "personal" theories for an informal review and feedback. (99.9% of the time it is full of nonsense.)" and "If you are not actively advocating a speculative theory or hypothesis it is OK to post it in the appropriate part of the forum (New, Physics, etc) for discussion." so again, may I ask, am I unable to view the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted.", because I am new to this site? or is it a problem with my Browser? or is there another discussion about this article that I am either not able to view, or simply unaware of? Edited April 6, 2018 by et pet delete empty line space ? -1
geordief Posted April 6, 2018 Posted April 6, 2018 8 minutes ago, et pet said: 1.) is it because I am new to this site that I cannot read the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted." In my Browser, I can only Read Three(3) Posts from "Strange" : 1.) says "I saw this too. Very interesting. I was going to post about it but you beat me to it!" ; 2.) says "Nothing to apologise for and no reason to have the post deleted. It is an interesting news story." and "There is nothing speculative in this post. (Which is why it has been moved to Science News. Because it is news. About science.)" ; 3.) says "No need to apologise. The "Speculations" section of the forum is for people to present their own "personal" theories for an informal review and feedback. (99.9% of the time it is full of nonsense.)" and "If you are not actively advocating a speculative theory or hypothesis it is OK to post it in the appropriate part of the forum (New, Physics, etc) for discussion." so again, may I ask, am I unable to view the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted.", because I am new to this site? or is it a problem with my Browser? or is there another discussion about this article that I am either not able to view, or simply unaware of? It is possible to "collapse"or show sections of (or quotes within) posts by clicking on the small arrow inside a small circle to the left of where it says,for example "19 hours ago,Strange said" Perhaps that is the problem? If the arrow has been inadvertently clicked then perhaps some of the post may be invisible or it may need to be clicked to show the various quotes.
Strange Posted April 6, 2018 Posted April 6, 2018 31 minutes ago, et pet said: is it because I am new to this site that I cannot read the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted." I think you are taking this too literally. I said it was "news". That implies it is new. Hence it can be described as a discovery. That's all. What beecee said was an indirect quotation; he used his own words to paraphrase my comment (and then added his own thoughts).
beecee Posted April 6, 2018 Posted April 6, 2018 (edited) 6 hours ago, et pet said: 1.) is it because I am new to this site that I cannot read the Post in this discussion where "Strange" has said : " As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted." 5 hours ago, Strange said: I think you are taking this too literally. I said it was "news". That implies it is new. Hence it can be described as a discovery. That's all. What beecee said was an indirect quotation; he used his own words to paraphrase my comment (and then added his own thoughts). Bingo! again as Strange has suggested. I really cannot see anything too complicated in what I said.. Quote " Science is a discipline in continued progress. As Strange has said, this is a discovery, although other interpretations may be possible, the likelyhood is that they are correct. If in the future, evidence turns up showing that they are/were mistaken, the new model will then be accepted. The interpretations are obviously from credentialed professional cosmologists and scientists in general, through the proper channels and via the scientific methodology. That is far removed from adhoc, unevidenced and unprofessional ideas and claims from any Joe Blow with access to a public forum. Nice article...thanks." The meat in what I said is highlighted. It seems you have trouble of not being able to see the woods for the trees? But again, thanks, certainly an Interesting article. On 4/6/2018 at 2:16 AM, et pet said: The galactic centre is already known to teem with stars, supernovae, pulsars, gas and dust, and the humongous black hole called Sagittarius A*, whose mass is equivalent to four million suns. Simulations have long suggested that many smaller black holes – those with masses around the same as our sun – also exist in the Milky Way’s centre and the middles of other galaxies, though only a single one has ever been spotted. Combing through archival data from NASA’s Chandra X-ray Observatory, Charles Hailey at Columbia University in New York and his colleagues were able to finally tease out a signal that appears to be coming from 12 stellar-mass black holes that have sun-sized stars orbiting them. " https://www.newscientist.com/article/2165505-the-centre-of-our-galaxy-may-be-swarming-with-10000-black-holes/ Actually this is incredible science and highlights the advances in technology that seems to be proceeding at tremendous pace and once again confirms what was earlier suggested and hypothesised. Obviously the far more densely packed galactic center, and the expected violent interactions, has lead to difficulty in "teasing out a signal" among the many other interactions between binary/trinary stellar partners, including Neutron stars accumulating matter and eventually overcoming its NDP. And of course LIGO and Virgo have shown us that intermediate and stellar size BH's are probably more common then once thought. Edited April 6, 2018 by beecee
et pet Posted April 6, 2018 Author Posted April 6, 2018 (edited) 7 hours ago, Strange said: I think you are taking this too literally. I said it was "news". That implies it is new. Hence it can be described as a discovery. That's all. What beecee said was an indirect quotation; he used his own words to paraphrase my comment (and then added his own thoughts). Thank you, Strange. I must apologize(constantly, it seems!), I am new to this type of site. It is different than http://forum.gibson.com I do not even know what the Green Cube and Red Cube highlighted numbers signify, nor the Yellow Circles, nor the "+" and "-" numbers under the "Members". We do not have them at http://forum.gibson.com . Edited April 7, 2018 by et pet
JacobsLadder Posted April 12, 2018 Posted April 12, 2018 One should be careful about accepting the concept of black holes. Let us not forget we have only observed areas of dense mass. We cannot be sure of the existence of singularities in our universe. I would not be surprised if another fundamental force preventing the formation of a singularity was discovered, although in terms of astronomy it is not relevant.
pzkpfw Posted April 12, 2018 Posted April 12, 2018 9 minutes ago, JacobsLadder said: One should be careful about accepting the concept of black holes. Let us not forget we have only observed areas of dense mass. We cannot be sure of the existence of singularities in our universe. I would not be surprised if another fundamental force preventing the formation of a singularity was discovered, although in terms of astronomy it is not relevant. They were predicted by theory, before observation was made; that's pretty strong stuff. Also, existence of a literal singularity is not considered fact. The idea of an infinitely dense infinitely small mass is mostly pop-science. All that's needed for a black hole is for its mass to be within a certain size, not necessarily a singularity. So "another fundamental force preventing the formation of a singularity" would not actually disprove or prevent black holes. 1
beecee Posted April 12, 2018 Posted April 12, 2018 38 minutes ago, JacobsLadder said: One should be careful about accepting the concept of black holes. Let us not forget we have only observed areas of dense mass. We cannot be sure of the existence of singularities in our universe. I would not be surprised if another fundamental force preventing the formation of a singularity was discovered, although in terms of astronomy it is not relevant. Most cosmologists doubt that any physical singularity exists, but singularities do not define a BH. The only defined singularity is that defined by the limitations bounds of applicability of our models such as GR. We most certainly can be sure of BH's, at least as certain as we can with any well supported scientific theory. One would wonder what LIGO has discovered at least 5 times so far if that was not the case.. 3
Strange Posted April 12, 2018 Posted April 12, 2018 5 hours ago, JacobsLadder said: One should be careful about accepting the concept of black holes. Let us not forget we have only observed areas of dense mass. We have observed objects that are sufficiently dense that they can only be explained by black holes. 5 hours ago, JacobsLadder said: We cannot be sure of the existence of singularities in our universe. I don’t think anyone considers singularities to represent physical reality. It just indicates that the current theory doesn’t work under those conditions.
Strange Posted April 13, 2018 Posted April 13, 2018 For those interested in the the original topic, there is a good overview of this work here: https://medium.com/starts-with-a-bang/the-milky-way-is-hiding-tens-of-thousands-of-black-holes-d7a2930fed1a
DrP Posted April 13, 2018 Posted April 13, 2018 I can't/haven't read that yet.. I will do when I get time later hopefully. From the title alone though I have a question (which might be explained in the article - sorry if so) - How does this leave the theory that there is a single supermassive black hole at the centre of each galaxy? Is that SMBH just an agglomeration of many BHs now then?.... do they not coalesce into one SMBH? Sorry if these are daft questions - it isn't my field but these thoughts came to mind when reading the thread title.
Strange Posted April 13, 2018 Posted April 13, 2018 10 minutes ago, DrP said: I can't/haven't read that yet.. I will do when I get time later hopefully. From the title alone though I have a question (which might be explained in the article - sorry if so) - How does this leave the theory that there is a single supermassive black hole at the centre of each galaxy? The answers are mainly in the first paragraph Quote At the center of practically every galaxy is a supermassive black hole, where millions or even billions of solar masses worth of material collect in a single location. Surrounding them, however, should be not only a slew of fast-moving stars, but tens of thousands of smaller black holes, formed from the corpses of massive stars that should have existed in the galactic center’s vicinity. There are a large number of stars created and dying in the centre of the galaxy, because of the large amounts of gas and dust there, so there should be many black holes. They can't be detected directly (because they are black holes) so this study looks for indirect evidence that they are there. 1
DrP Posted April 13, 2018 Posted April 13, 2018 (edited) 12 minutes ago, Strange said: The answers are mainly in the first paragraph There are a large number of stars created and dying in the centre of the galaxy, because of the large amounts of gas and dust there, so there should be many black holes. They can't be detected directly (because they are black holes) so this study looks for indirect evidence that they are there. I would have thought that they would be harder to detect than normal due their close proximity to the SMBH... I would guess the SMBH would obscure the smaller ones in orbit around it. Looking for a total shadow in a total shadow against a pitch black background. Thanks - I'll have a read later. On 12/04/2018 at 9:49 AM, JacobsLadder said: One should be careful about accepting the concept of black holes. Let us not forget we have only observed areas of dense mass. We cannot be sure of the existence of singularities in our universe. I would not be surprised if another fundamental force preventing the formation of a singularity was discovered, although in terms of astronomy it is not relevant. They are not thought of as singularities anymore I do not think... Mathematically maybe - but not in actual space. We discussed this here over a decade ago and it was thought then that they were actual physical singularities.... I didn't believe it then and still do not. We now know it has a size etc... I think the singularity is a dated concept. I am sure I will be corrected if I am wrong. As I said - I'm not an expert, but obviously an interested observer. @Strange - can you correct me if I am wrong please - The singularity is the mathematical depiction which has, rather recently, been shown to be pure maths and not practice. Black holes HAVE been detected now. indirectly and are, of course, not actually singularities but actually pretty big. Thanks. 37 minutes ago, Strange said: The answers are mainly in the first paragraph Thanks - so they were! lol. Strange - could you correct me if I am wrong in my reply to Jacobs Ladder above please. Thanks. Edited April 13, 2018 by DrP
Strange Posted April 13, 2018 Posted April 13, 2018 2 hours ago, DrP said: @Strange - can you correct me if I am wrong please - The singularity is the mathematical depiction which has, rather recently, been shown to be pure maths and not practice. Black holes HAVE been detected now. indirectly and are, of course, not actually singularities but actually pretty big. So, a black hole is defined by the event horizon, which is the [spherical] surface where nothing, not even light, can escape. The radius of the event horizon is proportional to the mass of the black hole, so is large (for 1 solar mass it is about 3km). The singularity is what happens when you apply General Relativity to the internals of the black hole. It means that curvature and density become infinite. I don't think anyone considers to represent reality. We probably need a theory that is able to take quantum effects into account in these extreme circumstances to have a better idea of what happens inside a black hole. There is no evidence a singularity doesn't exist (we haven't yet directly observed a black hole and wouldn't be able to see what goes on inside anyway!)
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