The appearance of the glow will give the first clues about the interstellar medium that the cloud must pass through to approach the black hole, says Eliot Quataert at the University of California, Berkeley, who was also a co-author of the gas-cloud-discovery paper. The density of the space the gas cloud ploughs through will affect its glow, for example: just as a meteor that ploughs through Earth’s atmosphere will put on a very different light show from a meteor zipping through the airless region above the Moon. Characterizing the interstellar medium “gives us some very important clues about how the black hole gathers up gas from its surroundings, and addresses the fundamental question of how massive black holes grow at the centers of galaxies," Quataert says.
This article is reproduced with permission from the magazine Nature. The article was first published on September 11, 2012.
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14 Comments
Add CommentIs it possible that the gas cloud can never make it past the event horizon? In other words, black holes grow only by merging with other black holes.
Reply | Report Abuse | Link to thisIt will make it past the event horizon, but we will not see it after that.
Reply | Report Abuse | Link to thisI believe black holes at the centre of galaxies are anti-matter stars, made from all the anti-matter that was formed simultaneously with matter. Perhaps anti-matter clumps more and was the first to form stars. Now you should have 2 event horizons, one between the black hole and all the matter it is attracting and another between the antimatter star and the region where matter and antimatter annihilates itself.
When two black holes will merge, matter within event horizons of two BHs will merge effectively.
Reply | Report Abuse | Link to thisYou said "within" the event horizon. I referred only to matter outside the event horizon.
Reply | Report Abuse | Link to thismatter that is falling towards the black hole will pass through the event horizon from its point of view. It's only from a distant observer's point of view that the matter appears to never pass the event horizon.
Reply | Report Abuse | Link to thisTherefore, the matter within the event horizon is basically the matter that makes up the black hole, and when two black holes merge, that matter will also merge.
If matter from outside an event horizon can not enter event horizon of a BH, how matter within event horizon of another BH, on merging of two BHs, will enter the combined event horizon of submerged BH.
Reply | Report Abuse | Link to thisGravitational interaction resulting from merging of two BHs may be much more intense than as applicable upon matter lying outside the event horizon of a single BH, therefore, TD may also be equally high.
It is my understanding that the Gravitational Time Distortion at the event horizon is so great that (from our perspective) the matter is just frozen at the horizon and never actually enters. Meanwhile, from the matter's own perspective, it travels through in normal time. I have seen Leonard Susskind describe this on various documentaries. I believe that is the solution to the problem of lost information that black holes present.
Reply | Report Abuse | Link to thisOf course, any of the answers given to this are completely theoretical. Nobody knows what really happens...although hopefully the coming observations will help to correct that.
New observations made this year of G2 have improved ephemerides wrt the encounter next year with Sag A*. Not only is the speed and degree of tidal disruption of G2 greater than predicted (due to increased orbital eccentricity), but the estimated closest passage of the cloud has decreased to 2200 Schwarzschild radii and the predicted perihelion passage has now shifted to early September 2013 (specifically Sep 10, 2013).
Reply | Report Abuse | Link to thisDetails of the new observations have been submitted to the Astrophysical Journal and posted online: http://arxiv.org/abs/1209.2272v1
Thanks for the interesting link.
Reply | Report Abuse | Link to thisThat report states that that the infalling gas cloud has a mass ~3 Earth masses.
While the Nature article's referenced report argues somewhat convincingly that the cloud contains a low mass star (0.3 Solar masses - minimum to form a stable disk) surrounded by a (diminished) tidally stretched protoplanetary disk, this seems to conflict with your reference's mass estimate of 3 Earth masses for the entire cloud. In fact, your reference concludes:
"Overall, a simple ballistic gas cloud, which is being tidally sheared, is an excellent description of the
data available. The origin of such a cloud remains puzzling."
For the Nature article source report, please see:
Ruth A. Murray-Clay & Abraham Loeb, (2012), "Disruption of a proto-planetary disc by the black hole at the milky way centre",
http://www.nature.com/ncomms/journal/v3/n9/full/ncomms2044.html
http://arxiv.org/pdf/1112.4822.pdf
BTW, even if the (low-mass) stars within the ring of stars encircling the MW's SMBH can or do include protoplanetary disks, that is not evidence that they form planets.
Reply | Report Abuse | Link to thisAs I understand, almost all protostars accreted within a molecular cloud form a protoplanetary disk, even though most (especially low mass) stars do not form planetary systems. Please see
http://en.wikipedia.org/wiki/Protoplanetary_disks#Formation
In reviewing other references to G2 wrt mass, I found Burkert et al point out that the total mass of the system "could be substantially larger than G2's estimated mass".
Reply | Report Abuse | Link to thisThis same paper looks at two likely scenarios for the formation of G2.
1)Diffuse cloud scenario - the cloud consists of shocked wind material ejected from a Wolf-Rayet or Luminous Blue Variable(LBV) star.
2)Compact source scenario - the cloud is associated with a compact source eg:
a. Low mass star with a protoplanetary disk (ala Murray-Clay & Loeb)
b. A compact planetary nebula
c. An evaporating low mass star, brown dwarf, or Jupiter-mass planet.
Future observations should help determine the precise nature and origin of the cloud. The Burkert et al paper "Physics of the Galactic Center Cloud G2, on its Way towards the Super-Massive Black Hole" can be found here:
http://arxiv.org/abs/1201.1414
If the 2013 date for infalling gas is correct, we will experience a solar response? The cold infalling gas is heated and jetted outward? Is this jet a way to see 'action at a distance'? I am not convinced the AGN eats planets; I see the gas as the convertible agency.
Reply | Report Abuse | Link to thisScientists have found not one but two stars at the galaxy center hole that orbit each other. Wonderful info.
There are theories that tie a galactic center activity to our solar system such as Miles Mathis'.
Nov 22 says black hole at galaxy center flaring. Is it our gas cloud?
Reply | Report Abuse | Link to thisThe problem with these info briefs is that there never is any connection and leaves us without follow up.
The article contains several contradictions. From our point of view, the falling material will never cross the event horizon. It doesn't have to be as seen by a "distant observer" as posted earlier, but any observer not traveling with the matter being pulled in. From wikipedia:
Reply | Report Abuse | Link to this"Likewise, any object approaching the horizon from the observer's side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses." http://en.wikipedia.org/wiki/Event_horizon