Black holes have simple feeding habits

June 18, 2008
Composite Image of M81 with Inset
Caption: This composite image of M81 includes X-rays from the Chandra (blue), optical data from Hubble (green), infrared from Spitzer (pink) and ultraviolet data from GALEX (purple). The inset shows a close-up of the Chandra image where a supermassive black hole about 70 million times more massive than the Sun lurks. A new study using data from Chandra and ground-based telescopes, combined with detailed theoretical models, shows that the giant black hole in M81 feeds just like ones with masses of only about ten times that of the Sun. Credit: Credit: X-ray: NASA/CXC/Wisconsin/D.Pooley and CfA/A.Zezas; Optical: NASA/ESA/CfA/A.Zezas; UV: NASA/JPL-Caltech/CfA/J.Huchra et al.; IR: NASA/JPL-Caltech/CfA

The biggest black holes may feed just like the smallest ones, according to data from NASA's Chandra X-ray Observatory and ground-based telescopes. This discovery supports the implication of Einstein's relativity theory that black holes of all sizes have similar properties, and will be useful for predicting the properties of a conjectured new class of black holes.

The conclusion comes from a large observing campaign of the spiral galaxy M81, which is about 12 million light years from Earth. In the center of M81 is a black hole that is about 70 million times more massive than the Sun, and generates energy and radiation as it pulls gas in the central region of the galaxy inwards at high speed.

In contrast, so-called stellar mass black holes, which have about 10 times more mass than the Sun, have a different source of food. These smaller black holes acquire new material by pulling gas from an orbiting companion star. Because the bigger and smaller black holes are found in different environments with different sources of material to feed from, a question has remained about whether they feed in the same way.

Using these new observations and a detailed theoretical model, a research team compared the properties of M81's black hole with those of stellar mass black holes. The results show that either big or little, black holes indeed appear to eat similarly to each other, and produce a similar distribution of X-rays, optical and radio light.

One of the implications of Einstein's theory of General Relativity is that black holes are simple objects and only their masses and spins determine their effect on space-time. The latest research indicates that this simplicity manifests itself in spite of complicated environmental effects.

"This confirms that the feeding patterns for black holes of different sizes can be very similar," said Sera Markoff of the Astronomical Institute, University of Amsterdam in the Netherlands, who led the study. "We thought this was the case, but up until now we haven't been able to nail it."

The model that Markoff and her colleagues used to study the black holes includes a faint disk of material spinning around the black hole. This structure would mainly produce X-rays and optical light. A region of hot gas around the black hole would be seen largely in ultraviolet and X-ray light. A large contribution to both the radio and X-ray light comes from jets generated by the black hole. Multi-wavelength data is needed to disentangle these overlapping sources of light.

"When we look at the data, it turns out that our model works just as well for the giant black hole in M81 as it does for the smaller guys," said Michael Nowak, a coauthor from the Massachusetts Institute of Technology. "Everything around this huge black hole looks just the same except it's almost 10 million times bigger."

Among actively feeding black holes the one in M81 is one of the dimmest, presumably because it is "underfed". It is, however, one of the brightest as seen from Earth because of its relative proximity, allowing high quality observations to be made.

"It seems like the underfed black holes are the simplest in practice, perhaps because we can see closer to the black hole," said Andrew Young of the University of Bristol in England. "They don't seem to care too much where they get their food from."

This work should be useful for predicting the properties of a third, unconfirmed class called intermediate mass black holes, with masses lying between those of stellar and supermassive black holes. Some possible members of this class have been identified, but the evidence is controversial, so specific predictions for the properties of these black holes should be very helpful.

In addition to Chandra, three radio arrays (the Giant Meterwave Radio Telescope, the Very Large Array and the Very Long Baseline Array), two millimeter telescopes (the Plateau de Bure Interferometer and the Submillimeter Array), and Lick Observatory in the optical were used to monitor M81. These observations were made simultaneously to ensure that brightness variations because of changes in feeding rates did not confuse the results. Chandra is the only X-ray satellite able to isolate the faint X-rays of the black hole from the emission of the rest of the galaxy.

This result confirms less detailed earlier work by Andrea Merloni from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany and colleagues that suggested that the basic properties of larger black holes are similar to the smaller ones. Their study, however, was not based on simultaneous, multi-wavelength observations nor the application of a detailed physical model.

Source: Chandra X-ray Center

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4 / 5 (1) Jun 18, 2008
Wouldn't a significant surrounding halo of dark matter(or any matter) have the affect of reducing the apparent effect of a planet's gravity on anyone standing on the surface?

Wouldn't it be something like being closer to the center of a large mass? The lateral mass' effect being near negligible, and the mass above having a cancelling effect on the mass below. But then there's the mass below(or behind) the planet. Hmmm.
not rated yet Jun 18, 2008
Good question. Asuming the system is relatively uniform, you would only 'feel' the mass inside of a sphere that extends from your body to the center of mass of the system, this should corrospond with the center of the planet, meaning that a uniform distribution of matter outside of that sphere will have no effect on what you 'feel'.

I think. It's been a while.
5 / 5 (1) Jun 18, 2008
I would suspect not, because only a small portion of that disk would be on the other side of the center of gravity. But what does that have to do with this article anyways?
4 / 5 (2) Jun 18, 2008
I was wondering something simmilar in a different thread, only i reasoned that if there was an abundance of dark matter in your system, that it would accrete "alongside" the stars and planets, condensing and overlaping around them, and thus combining gravities. I wouldnt expect that dark matter in the space around a system would have any effect on the planets surface gravity any more that the matter in the planets atmosphere would. I do wonder though, if dark matter follows matter gravitationally. by this reasoning, there could be a "dark earth" either within our own, or maybe even bigger than earth, axtending outward. The question is, does dark matter gravitate toward itself, or just ordinary matter?
not rated yet Jun 18, 2008
Ah, yeah, wrong thread. But thanks for the answers.
Sorry about that.
1 / 5 (1) Jun 23, 2008
Among actively feeding black holes the one in M81 is one of the dimmest, presumably because it is "underfed".

So what the fuck is a black hole then? The only hole that would be really black interpreting this stuff, appears to be a hole that is dead or totally underfed.

I thought a black hole was black because radiation could not escape... obviously I was badly informed.

So this story is really about 'almost black holes', like ... 'grey holes' or uuhh ... 'brown holes'.

Underfed holes? Biologists also study shit to determine what has been eaten. waahhhahaaa.

My conclusion:

black holes that eat well, are not black.
5 / 5 (1) Jun 23, 2008
Can black holes eat dark matter? I would tink so as dark matter DOES seem to interact with matter via gravity, and since a black hole is basically gravity incarnate wouldn't any halos of the stuff eventually get sucked in and add to the mass of the hole in some way?
not rated yet Jun 23, 2008
Good question, modern, I have always heard about ordinary matter following dark matter along the cosmic web, but does this interaction have a reciprocal effect?

and to hibiscus, You are right, black holes are not black. you should go back a couple of decades and re read the posts on that subject. Black holes evaporate as they lose particles at the event horizon through quantum fluctuations. its the uncertainty principle in effect. particle pairs emerge from the void on the horizon, and sometimes one of them will escape. More active black holes are more uncertain, to be short, and produce more radiation.
not rated yet Jun 27, 2008
... and to hibiscus, You are right, black holes are not black. you should go back a couple of decades and re read the posts on that subject.

So... let's call 'm grey holes then.. or dark red holes or dark yellow holes or whatever, but we should defintely stop calling them black holes.

"Black holes are not black" really sounds rediculous as black holes should really be black.

Hm, so no insight gained during the last decades?
At least we agree now that "black" holes do not exist.

Black holes evaporate as they lose particles at the event horizon through quantum fluctuations. its the uncertainty principle in effect. particle pairs emerge from the void on the horizon, and sometimes one of them will escape. More active black holes are more uncertain, to be short, and produce more radiation.

Thanks for the lecture :-)

One question...

So... these grey holes evaporate and when they eat more, they evaporate faster? Does that mean that this quantum flux whatever radiation has a speed that exceeds the escape velocity of a more or less grey hole?

or is escape velocity a totally ancient concept in this context an I should go back to the beginning of time and read those posts?

old men never learn... do they? :-)
not rated yet Jun 27, 2008
Well, particles dont need to have an escape velocity if theyre created precisely on the event horizon and happen to cross outside to be caught by the EM field and shot out of the polar regions into deep space. this is the source of such x ray emmissions.

A black hole evaporates at an expoential rate according to it's mass, and as it shrinks from lack of input, it will evaporate faster and faster, but that doesnt mean it will get "brighter" Normal evaporation rates are not sufficient enough that we would say the black hole is luminous, that is untill it reaches a point somewhere below 1 solar mass, when its gravity can no longer support it's own energy, it evaporates faster and faster untill it explodes.

conversely, when the black hole is in feeding mode, its brightness is a result of increased activity at the event horizon. If you could peer inside, youd definitely see the hole as black, right before your atoms were torn apart.

I reccomend you check out Hawking's earlier work compared to his more recent stuff. there was a lot of contreversy regarding his first assumption that no information can escape from a black hole. Many agreed, but most diddnt, on grounds that this would violate the laws of thermodynamics. Hawking later retracted his ideas and formaly admitted he was wrong, along with submitting the above mechanism for information loss. I read it first in the newspaper at 7-11. Dont make yourself feel old, Its hard to keep up with us 25 year old punks with no college education.
not rated yet Jul 25, 2008
I understand that there is still some disagreement in respect to evaporation.

However this evaporation is not expected to be perceived as being brighter than black - just depends on your range of (visibility) I suppose.

In conclusion yes black holes are in fact black. They will radiate light and x-rays etc from orbiting masses as these masses increase in velocity around the black hole prior to crossing the event horizon.

We have to assume that some mass does get to cross the event horizon or there would not be any super massive black holes.

As for the range of sizes of black holes from 10 solar masses to millions of solar masses - they would have to be every size in between, it is simply impossible that there would not be every size in between.

Further more - whenever discussing black holes and there size we should include information about the rate of evaporation (if indeed they do evaporate) as this size may be rapidly diminishing.

After all this article is about Black hole in M81 7 million times more massive than the regular small types of black hole. Based on exponential increases in evaporation rates one would have to wonder if this black hole is growing or shrinking.

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