Milky Way's Black Hole a Gamma Source?

eldavojohn writes "A paper recently accepted for publication (preprint here) proposes a sound explanation for the source of the gamma rays that permeate our galaxy. The Milky Way's central object Sagittarius A*, widely believed to be a supermassive black hole, is now suspected to be the source. To test this theory, two scientists created a computer model to track the protons, flung outward with energies up to 100 TeV by the intense magnetic fields near the event horizon, as they make a random walk through the plasma environment. It can take thousands of years for them to travel 10 light-years from the black hole, where they collide with lower-energy protons to form pions. These decay into gamma radiation emanating from a torus-shaped region around the central object."

Comments

Brings to mind this question ....

[Archangel Michael]

"The Milky Way's central object Sagittarius A* [CC], widely believed to be a supermassive black hole, is now suspected to be the source."

Would that make it an "A-Hole" ?????

Re:Brings to mind this question ....

[PhrostyMcByte]

Coming from Sagittarius A*, the gamma radiation will obviously have little difficulty finding a path to earth.

Re:Brings to mind this question ....

[slashgimp]

I sense an oncoming joke about Administratium, what with all the talk of A-holes, peons, and things taking thousands of years to accomplish a task ;)

Whee!

Re:Brings to mind this question ....

[PhrostyMcByte]

Would someone please explain why parent is modded funny?

A* is a path finding algorithm. It is used in many games, such as Starcraft.

Re:Brings to mind this question ....

[Hoi Polloi]

I always thought the Milky Way was full of yummy nougat. Ummmmm....nougat

Black Hole

[alexj33]

The Milky Way's central object Sagittarius A*, widely believed to be a supermassive black hole, is now suspected to be the source.

That black hole must really suck.

Paging Louis Wu

[sqlrob]

Long Shot is ready for departure

Re:Paging Louis Wu

[j_presper_eckert]

God, how I love the concept of the "Long Shot". 75 seconds to the light-year [-swoon-].

Imagine a Beowulf Shaeffer cluster of those...

Thanks folks, I'll be here all week. Be sure to tip your Puppeteer generously!

Distribution of life?

[PIPBoy3000]

I wonder if that means that life is only possible near the outer arms of the galaxy? If you assume that gamma rays are a point source in the middle of our galaxy, what sort of radiation levels are you going to see closer to the center?

Re:Distribution of life?

[Normal Dan]

There are already dangerous levels of radiation within our own solar system, however, we are protected by an atmosphere. I would imagine one of two possibilities. Any planet with the potential for life closer to the center of our galaxy would have enough shielding of some sort (either a thick atmosphere or a thick ocean) to allow life to form on almost any suitable location in the galaxy. The other possibility is, life can exist in high amounts of radiation, but it might not be life as we know it.

Re:Distribution of life?

[MollyB]

I'm no scientist, but as amateur astronomer and cosmology 'nut' I can say that even though the central portion (the "bulge") may have higher levels of radiation of all frequencies that would be damaging to life-as-we-know-it, the fact remains that out in the spiral arms of the galaxy there are many stellar nursuries (huge molecular clouds that occasionally have a shock wave pass through that can ignite new stars). These regions sometimes congeal a massive star which burns in a few millions of years rather than the multi-billion life our sun can expect. This star then explodes quite violently, and fries the surrounding neighboorhood, not only with electromagnetic radiation of many frequencies (gamma included), but would bombard nearby star systems with ionizing radiation (unhealthy stuff like the nuclei of iron, etc.) even if it is in the galactic suburbs.
So, maybe it is lucky it'd take about 30,000 years at the speed of light to get to the center; it is dangerous enough way out here, nevermind the comets and asteroids. 8)

Re:Distribution of life?

[Dan Slotman]

Actually, other parts of the galaxy are farther from the milky way and other black holes. These arms, teeming with life, use gamma rays to communicate and travel. They haven't come calling since our arm is poisoned with radiation, making interstellar travel prohibitively dangerous!

Re:Distribution of life?

[Artifakt]

There are definitely at lest one other self replicating molecule already known (RNA). RNA however has a much higner rate of copying errors, and lower error rates actually promote selection (down to a minimum - obviously zero errors means no selection at all, but even DNA is somewhere still well above the calculated ideal error rate for fastest selection).
        This seems somewhat counter-intuitive, but if you think of a species as a set with somewhat fuzzy boundaries, more errors mean the boundaries are fuzzier. More members of a species deviate farther from the average type. Since enough members of a species usually survive long enough that the avaerage organism reproduces once, most members are already pretty well adapted to their niche. Higher mutation rates therefore mean more members are ill adapted, so selection actually slows down because more species get out of balance and die out faster and more often without leaving a successor species. A higher mutation rate also means more organisms have 2 or more mutations, and since most mutations are negative, a swamping effect occurs, where possibly good mutations don't ever get a chance to be selected. A really high mutation rate means genes don't just find themselves increasingly surrounded by defective partner genes, they actually get a chance of being overwritten before they linger for enough generations to be tested.
        For sexually reproducing species, the chance of not being able to successfully breed with a given other goes up very quickly, etc, so sex becomes a less successful option than parthenogenesis, etc, and again selection slows down even more.
        Most biologists think RNA was once dominant on our planet, and that there were other replicators, more primative and having higher error rates, before RNA. It's possible that some of these are more optimal under other conditions, i.e. more or less radiation, heat, or in other atmospheres. It's also possible some codes that were never developed here on Earth have developed in other places.

oblig.

[Rob T Firefly]

What does God need with a starship?

Do we know?

[pygmy_jesus]

I've been semi-interested in Cosmology/Astrophysics lately, and from everything I've seen and read so far, I've ascertained that we don't know much. Between dark matter, dark energy, gravity, black holes, big bang, etc. it seems like we just conveniently make up "stuff" to fit some model or equation. Do discoveries like this mean anything at this time considering there's no way to prove any of it?

Re:Do we know?

[MightyMartian]

I've been semi-interested in Cosmology/Astrophysics lately, and from everything I've seen and read so far, I've ascertained that we don't know much. Between dark matter, dark energy, gravity, black holes, big bang, etc. it seems like we just conveniently make up "stuff" to fit some model or equation. Do discoveries like this mean anything at this time considering there's no way to prove any of it?

Translation: I know the names of some scientific fields, but never read more than the science headlines in the newspaper. Clearly this is the fault of scientists.

Re:Do we know?

[Ibag]

While this probably is an accurate translation, GP has a point. A lot of science can seem rather ad hoc at times. Before we had discovered all the planets, scientists noted that the orbits of the known planets were not quite what they should be. Instead of declare that newton's theory of gravity was wrong, they theorized that there was an unknown planet. After doing some calculations, they determined where this planet had to be, looked up at the sky, and found Neptune.

Similarly, when cosmologists look at the apparent rate of expansion of the universe (and how that rate has changed over time), they get that if their model of the way things work (general relativity) is correct, then their estimates of the mass in the universe based on empirical observation cannot possibly be right. Instead of abandoning relativity and leaving a void in its place, they say, "This will work of there is a large amount of matter that we can't observe. Dark matter!" Of course, this doesn't resolve everything, and we need various other adjustments (like dark energy, or physical constants that aren't constant) which look like kludges, but which have predictive power and are the best answers we've got.

Do we "know" this is correct? Of course not! We don't even know that the next time we drop an apple, it will fall to the floor. Science is a process, though, and it isn't productive to dismiss the theories of today before we've seen the observations of tomorrow.

Re:Do we know?

[Fujisawa Sensei]

We know a lot more than you give us credit for, perhaps you need to read a little deeper, try Relativity by Albert Einstein. AE just made up stuff because observations didn't fit Newtons proven model. So he just made up some equations to match the observations. But alas his made up equations didn't correctly model acceleration or gravity, so he made up GR.

GR is a very accurate theory, and there is experimental evidence of it. The two most famous are the perihelion precession of Mercury, and stars visible near the eclipsed sun. Of course being semi-interested in Cosmology/Astrophysics you would already know that.

Stuff like Dark Matter that just doesn't get made up, it falls out naturally when equations which are shown to work in one situation are shown to fail in another. DM vs GR for example. There's a lot of guess work as to what DM is, but that's where life gets interesting, we don't know what it is. We know 'something' is there, we just don't know what the something is. DM isn't a convenience item, its a wart, because without the wart GR which is shown to work in other cases could be used to correctly model galactic motion.

Re:Do we know?

[ChrisA90278]

"Do discoveries like this mean anything at this time considering there's no way to prove any of it?"

There is no way in science to PROVE ANYTHING. All one can do is disprove a theory you can never prove a theory to be true. This is a very basic part of how science works

A theory is a good theory if it is predictive and makes good predictions and it is disprovable and it has not been disproved. But a theory can't be proven to be true.

Have you ever read Wittgenstein? Goggle the name. He wrote, long before the 1960's a question "Have I ever been to the moon?" He argued that while he thought he'd never been there and knew of no one who had he could not prove he's never been to the moon and further that such proof was impossible. Proof is very different from being very, very certain. He goes on to explain the difference and what can and can not be proven. Some things can never be proven not matter what you do

In science all you can be is "very certain" but must always be open to being proven wrong. For example we think and are very certain that light follows the inverse square law but can you prove that it ALWAYS does? It only takes one exception to disprove the theory but a trillion observations would not prove it true.

Re:Do we know?

[MightyMartian]

I think the rate of expansion is an awfully good example. The standard inflationary model does have a problem in that it doesn't predict the expansion rate we see. Scientists have two choices when the data and the model don't jive. They can either toss the model and start from scratch, or attempt to alter the model to reflect observations. The decision to do either is one based upon how well other predictions of the model perform. In the case of the inflationary model, other aspects of the theory do explain other observations very well, so while we know there's a problem, we also know that it isn't a problem that completely devestates the existing theory. It means that the theory is not complete, and so, rather than tossing the theory, cosmologists and physicists will seek to refine the model, and that's what they're doing.

I suppose someone who doesn't understand the fundemental process might find dark matter and the like to seem ad hoc solutions, but when you consider that the main theory involved (General Relativity) does such an incredibly good job of modeling most of the other phenomona we see in the observable universe, it seems more reasonable to invoke something, possibly unseen, that could be playing a part, rather than tossing out an entire theory.

Re:Do we know?

[Ibag]

Well, I think that there is an important way in which this is nothing like epicycles. With the theory of epicycles, people (I hesitate to call them scientists) were looking to describe how the heavens moved without much thought of why. Here, scientists are working with a theory of why the world behaves as it does, and is trying to tweak parameters to make the model obey observation. When people added circles within circles to make the epicycles more accurate, there was no reasonable explanation for why this should be the case. Now, we have a reasonable sounding explanation that "the physics of over there should be the same as the physics over here." This is science. That was not.

Re:huh?

[spun]

You're thinking of microwave radiation.

Man the Battlestations!

[eno2001]

It's time to cue the Goatse jokes and links! Let's give 'em hell boys!

Same here

[quokkapox]

I've been semi-interested in Computer Science/Mathematics lately, and from everything I've seen and read so far, I've ascertained that we don't know much. Between dark fiber, optimal algorithms, P=NP, O(n log n) (and other equations like that), cryptography, etc. it seems like we just conveniently make up "stuff" to fit some model or equation. Do discoveries like this mean anything at this time considering there's no way to prove any of it?

[No offense intended--just pointing out that a lack of sophisticated understanding in a field of study does not imply the field is in any way bogus or the knowledge is "shaky". The reason it's called "dark matter" or "dark energy" is precisely because we aren't sure exactly what it is yet.]

Re:Same here

[$RANDOMLUSER]

You might want to take a look at (I am NOT making this up) VB Helper Tutorial: Does P = NP? ;D

Incorrect summary

[forand]

The summary makes it sound as though this is an explanation for the DIFFUSE gamma-ray emission seen in our Galaxy. This is not the case, the paper only discuss a source of gamma-rays observed to be spatially coincident with the Galactic center. Gamma-ray telescopes do not have high angular resolution so there is a possibility that the gamma-rays are not actually coming from the Galactic center in the first place. Finally this is not a new proposal. Proton acceleration near black holes is quite commonly discussed and accepted. Furthermore photo-pion production is a well known process that has been well measured in the lab. I think the real meat of this paper is that they are suggesting observations of emission associated with the black hole that we have observed gravitationally for a while now. This is the big news, not that the gamma-rays in our galaxy have been explained, not that protons make pions which decay into gamma-rays.

Re:Star near the black hole

[btgreat]

The article was talking about protons, not photons. I'm not exactly sure whether or not the motion is random, but it certainly shouldnt have any effect on whether the PHOTONS of the star are visible or not..

High Radiation Life Forms

[Lord Balto]

Of course. Life evolves to fit the current conditions. In a high radiation environment, I can imagine a life form that takes advantage of the high radiation levels to rapidly mutate and evolve, increasing its chances of survival in a hazardous environment. Actually, there are plants on this very planet that for some reason have developed the abilty to mutate rapidly. The hawthorn for example. There was a point when there were hundreds of named species of hawthorn. Before the botanists realized the damned things were just mutating spontaneously.

Water Bears

[Neutrino Linguino]

Tardigrades [aka Water Bears], which live everywhere on this planet Earth, can...
1) resist storage in liquid nitrogen
2) survive in contact with mineral acids, organic solvents, and boiling water
3) survive in a a vacuum and under high pressure
4) withstand ionizing radiation of over 600,000 roentgens (500 roentgens would be fatal to a human)

Re:Water Bears

[khallow]

Hmmm, you got to wonder if that's a fortuitous coincidence or if that amazing ability to survive was spurred by something in their environment. Now that I think of it, any organism that can exist in an indefinite "cryptobiosis" state (ie, when all metabolic processes stop for a possibly long period of time) would do better if it had some of the above properties. In particular, the ability to survive extreme genetic damage is necessary IMHO. Suppose humans had similar abilities. If I entered cryptobiosis say in an "average" North American location, I'd receive a whole body dose of perhaps 3 millisievert per year (maybe much less since I'm no longer breathing carbon 14 and radon). Since I'm in cryptobiosis, I have no ability to repair radiation damage, it's like I experience this huge pulse of radiation damage.

According to here, every 100 millisievert results in a 5% boost (supposedly) in average life-time cancer rates, and 1000 or more millisievert is life threatening. So 30-40 years gives me a 5% boost in cancer rates and 300-400 years of cryptobiosis gets me up to 1000 millisievert. I can't survive roughly 3000 or more years (10 sievert which is automatically lethal) because I literally receive a fatal dose of radiation before I have a chance to repair it. We ignore that there may be other ionizing processes (chemical or thermal, for example) that would vastly shorten this time.

Re:huh?

[StikyPad]

Well now I'm thinking of heating up a frozen BBQ sandwich. Thanks.

Re:Star near the black hole

[gr8_phk]

Sorry. My dumb. I read too fast and saw all this stuff about gama radiation and my brain converted protons into photons. Hey, there you have it - proton decay due to dim gray matter - er uh dark matter.

Re:Paging Teela Brown

[savage1r]

Get ready to recieve my Hot Needle of Inquiry.