Formation of Black Holes from Neutron Stars and White Dwarfs

[p53ud0 dr34m5]

But, get used to the notion that black holes are real.

Right, Chronos, right...I've been reading up on black holes recently, but all I've been able to derive from my readings is: most black holes form at the center of galaxies, or they form at the center of massive star clusters. I have one question. Why hasn't there been a black hole observed to form inbetween a galaxy or away from a massive star cluster? I used to prize the idea of a black hole, but that idea is slowly fading and becoming harder to grasps as true.

 

[selfAdjoint]

Right, Chronos, right...I've been reading up on black holes recently, but all I've been able to derive from my readings is: most black holes form at the center of galaxies, or they form at the center of massive star clusters. I have one question. Why hasn't there been a black hole observed to form inbetween a galaxy or away from a massive star cluster? I used to prize the idea of a black hole, but that idea is slowly fading and becoming harder to grasps as true.

Black holes are black. No light gets out of them, so they can't even reflect light. What we see in the centers of galaxies is the infalling matter, which is raised to high energies by its fall and radiates before it hits the event horizon. Also the BH is surrounded by perhaps hundreds of stars in orbit, as shown in the time lapse pictures marcus linke to.

So what could you see of a black hole out between the galaxies, away from any matter that could signal its presence? There wouldn't be anything to see. There might be black holes out there, but we'd never know it. Even their gravity wouldn't show since they'd be so far from visible matter.

 

[p53ud0 dr34m5]

So, why hasn't there been an observable black hole residing between two galaxies. My other question: why hasn't there been an observable black hole not accompanied by a huge star cluster? The latter of the questions is probably answerable with common knowledge. The former I have been unable to answer through book and journal research. Maybe I looked over seomthing? I don't know. selfAdjoint, you seem pretty sufficient in your knowledge. Could you help answer my questions?

 

[Chronos]

I can't answer for SA, but I can tell you this. The only way to detect a black hole is to observe the gravitational influence they have on nearby objects. If you know a better way, propose it.

 

[da_willem]

Right, Chronos, right...I've been reading up on black holes recently, but all I've been able to derive from my readings is: most black holes form at the center of galaxies, or they form at the center of massive star clusters. I have one question. Why hasn't there been a black hole observed to form inbetween a galaxy or away from a massive star cluster? I used to prize the idea of a black hole, but that idea is slowly fading and becoming harder to grasps as true.

A Black hole is still made of matter. in between galaxies space is pretty much empty, so there is no matter that can agglomerate into a massive object like a black hole. Notice that the is no conclusive observation of a black hole, but it seems reasonable to assume that in the center of a galaxy there is a agglomeration of mass so that not even light can escape.

The only way to detect a black hole is to observe the gravitational influence they have on nearby objects. If you know a better way, propose it.

If there are things like small black holes, you could detect the Hawking radiation as a last outburst of energy before the black hole is totally evaporated. But ofcourse there is no guarantee that these things exist. Futhrmore.

If matter orbits a black hole, by a proces of collisions it radiates energy lowering the orbit of the matter, with the result that it finally feeds the black hole. This radiation can be observed?! There must be some characteristics that differ from a normal massive star with matter orbiting it. The black hole does not radiate very much itself, so maybe this can be obeserved?

 

[p53ud0 dr34m5]

The only way to detect a black hole is to observe the gravitational influence they have on nearby objects.

Just because an object has been observed to surrender to an intense gravitational influence, does not mean you can utter out "black hole" as a conclusive statement. I'll keep my ideas about the faith of black holes withdrawn. On that note, I won't contribute my method.

I have different views on black holes, which is probably self-evident. I was just wondering how well you people would hold up to your current model.

da_willem, let's think outside of the box for a moment. What if a black hole really isn't neccessarily a "black hole," rather it is just an area with an intense pressure gradient? It is an area where the heat is so intense due to the pressure, that the only types of radiation that are given off are x-rays and gamma rays. So, it is still a "black hole," because no VISIBLE light is seen to escape. I don't know I am just asking questions and putting up case scenarios. I'm very curious in the way people think.

 

[da_willem]

da_willem, let's think outside of the box for a moment. What if a black hole really isn't neccessarily a "black hole," rather it is just an area with an intense pressure gradient? It is an area where the heat is so intense due to the pressure, that the only types of radiation that are given off are x-rays and gamma rays. So, it is still a "black hole," because no VISIBLE light is seen to escape. I don't know I am just asking questions and putting up case scenarios. I'm very curious in the way people think.

You seem to be looking for interpretations of the word 'black hole'. It is the name given to an object (their existence in nature aside) which has so much mass in such a small volume that you reach the point where the escape velocity exceeds c, before you reach it's surface. So no radiation can escape the object, hence the name. In this sense there's nothing strange about a black hole, all massive objects bend the trajectories of light...

 

[p53ud0 dr34m5]

You get an A+ in totally dodging the question. Haha, I must have been crazy or something when I asked my questions, so let me restate the questions. I'm hoping you guys can benefit from clarity.

When I mentioned no visible light can escape, I also meant no electromagnetic radiation in general. Why I said gamma and x-ray can escape, I have no idea. But what I meant was, what if the area that has been dubbed a "black hole" wasn't necessarily the classical definition of a black hole. By that I mean, What if a singularity was not present? What if some other entity is the cause for lack of emitting electromagnetic radiation? I am fully aware of the definition designated to a black hole, da_willem. No need to reiterate what's accessible to everyone.

I'm just looking for simple answers to simple questions.

 

[Chronos]

Correction noted and respected P53. The classical definition of a black hole is simple. Any object massive and small enough to have an escape velocity of 'c' is a black hole. The singularity arises from particle physics. When gravity is strong enough to prevent light from escaping, atomic forces, as we understand them are not strong enough to prevent atoms and their constituent particles from collapsing. But, many theorists do not believe they are crushed into zero volume, just into an extraordinarily dense state not yet understood.

 

[da_willem]

When I mentioned no visible light can escape, I also meant no electromagnetic radiation in general. Why I said gamma and x-ray can escape, I have no idea

Me neither

But what I meant was, what if the area that has been dubbed a "black hole" wasn't necessarily the classical definition of a black hole

There have been no area's been dubbed black holes, on the observation that a large mass is present yet not visible. You seem to think black holes are observed objects, and you would like to explain them without the notion of a classical black hole. A black hole just arises from theoretical arguments, and their existence is not yet proven.

what I mean, What if a singularity was not present? What if some other entity is the cause for lack of emitting electromagnetic radiation? I am fully aware of the definition designated to a black hole, da_willem. No need to reiterate what's accessible to everyone.

I'm just looking for simple answers to simple questions.

As Chronos pointed out; there may or may not be a singularity inside the event horizon of a black hole. If this is your concern with theory, I share that concern.

 

[meteor]

If you're asking yourself what came first, the egg or the chicken, I don't have the answer. If you're asking what came first, the black hole or the bulge, scientists have discovered now that the supermassive black holes at the centers of galaxies form before the bulge
http://www.spacedaily.com/news/blackhole-04k.html

 

[Chronos]

Good link meteor. Indeed there is an increasing amount of evidence to suggest massive black holes play a key role in galactic formation, especially 'normal' large galaxies like the milky way. Evidence of super massive black holes has been discovered in numerous other galaxie, many of which appear to be much more massive than the the central black hole in this galaxy.

 

[Nereid]

You get an A+ in totally dodging the question. Haha, I must have been crazy or something when I asked my questions, so let me restate the questions. I'm hoping you guys can benefit from clarity.

When I mentioned no visible light can escape, I also meant no electromagnetic radiation in general. Why I said gamma and x-ray can escape, I have no idea. But what I meant was, what if the area that has been dubbed a "black hole" wasn't necessarily the classical definition of a black hole. By that I mean, What if a singularity was not present? What if some other entity is the cause for lack of emitting electromagnetic radiation? I am fully aware of the definition designated to a black hole, da_willem. No need to reiterate what's accessible to everyone.

So let's take this step by step, shall we?
"what if the area that has been dubbed a "black hole" wasn't necessarily the classical definition of a black hole[/color]"
The easiest way to start with this question is to list the 'area(s) that have been dubbed "black hole"'! IIRC, such a list would include
- some objects in X-ray binaries
- the nuclei of some galaxies
- the cores of quasars
- something in, or near, the sites of certain supernovae remnants ('hypernovae')
In each case we can check the observations and logic which lead to the designation; in all cases I think you will find 'ergo, black hole' comes at the end of an extensive chain of reasoning and modelling, involving quite a bit of detailed (astro-)physics. In (almost?) all cases, this reasoning and modelling amounts to something like this (grossly oversimplified) 'there's an awful lot of mass there, and the density must be very high; we don't what collection of mass with that density could be, other than a black hole."

"What if a singularity was not present?[/color]"
Now this is truly a simple question Observationally, all that one can say is that there seems to be a lot of mass in a small volume; whether there's a singularity or not is entirely theoretical (well, AFAIK); one cannot observe anything about the internal (inside the event horizon) structure of a black hole.

"What if some other entity is the cause for lack of emitting electromagnetic radiation?[/color]"
Quite. The challenge, should you choose to accept it, is to describe, within the framework of presently accepted physics, what else it could be. Alternatively, produce a new theory, consistent with all astronomical observations and physics experimental results, which accounts for the apparent large mass and high density.

I'm just looking for simple answers to simple questions.

Aye, but here's the rub ... what if there are no simple answers (to those questions)? What if the questions themselves appear simple, but aren't? IMHO, it's extraordinarily easy to ask what appears to be a simple question, only to find it's highly ambiguous, vague, many questions rolled into one, ...

 

[catch.yossarian]

Light that enters the event horizon will goto the infitely dense singulairty at the centre of the black hole. Yes this does increase the nergy of the black hole; as mass and enrgy are equivalent this means that the mass of the black hole will increase.

Infinite mass means infinite inertia. It resists all motion.

One couldn't push a black hole out of their way like any other matter in space?

Thus can one not get rid of a black hole once its there? Will this mean that our universe is destined to become a wasteland of neutron stars and black holes?

Just thinking, disregard if this makes completely no sense.

 

[Nereid]

Infinite density is a very different animal than infinite mass! One thing which BHs do have is a definite, and very finite, mass. In that regard, they are no more difficult to push around (e.g. in a binary) than another lump of the same mass (e.g. a hydrogen burning star).

 

[i_zoned_out_in_class]

Okay, a black hole is created when a star novas. A black hole is made of dark matter. Stars and everything else are made of luminous matter. (Every ounce luminous matter, nine ounces dark matter) A black hole (Or any dark matter really) pretty much produces an "anti gravity". That's all I really know about the subject so I hope I helped.

 

[donjennix]

Exploring Black Holes

If you are not a Physicist and want to REALLY understand the math of a non-rotating, non-magnetic black hole (i.e., Schwarzschild black hole) you really should read Wheeler and Taylor's "Exploring Black Holes". It answers multitudes of difficult questions.