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Fraser
2006-Aug-24, 02:43 PM
The supermassive black holes thought to be lurking at the heart of most galaxies could create such a hostile environment around them that they prevent the formation of new stars. This is according to new research assisted by NASA's Galaxy Evolution Explorer (GALEX). The space-based telescope observed more than 800 galaxies, and found that the larger galaxies had fewer young stars. Astronomers believe that jets blasting out of supermassive black holes could clear out gas and dust; potential star forming material.

Read the full blog entry (http://www.universetoday.com/2006/08/24/supermassive-black-holes-prevent-star-formation/)

John Mendenhall
2006-Aug-25, 06:52 PM
Hmm . . so super-massive black holes might be self-limiting? There are perhaps no super-duper-massive black holes?

antoniseb
2006-Aug-25, 09:24 PM
I don't think this says that there is an upper limit to the mass of a Super-massive black hole. It does kind of imply that the larger the black hole is the faster the galaxy around it reaches non-star-forming maturity. It is possible (but not likely) that the great attractor is a super-jumbo black hole far beyond the scale of anything seen in a giant elliptical.

Blob
2006-Aug-25, 09:53 PM
The very largest black holes reach a certain point and then grow no more, according to the best survey to date of black holes made with the Chandra X-ray Observatory. Scientists have also discovered many previously hidden black holes that are well below their weight limit.
These new results corroborate recent theoretical work about how black holes and galaxies grow. The biggest black holes, those with at least 100 million times the mass of the Sun, ate voraciously during the early Universe. Nearly all of them ran out of 'food' billions of years ago and went onto a forced starvation diet.
On the other hand, black holes between about 10 and 100 million solar masses followed a more controlled eating plan. Because they took smaller portions of their meals of gas and dust, they continue growing today.

"Our data show that some supermassive black holes seem to binge, while others prefer to graze. We now understand better than ever before how supermassive black holes grow" - Amy Barger, University of Wisconsin in Madison and the University of Hawaii, lead author of the paper describing the results in the latest issue of The Astronomical Journal (Feb 2005).

One revelation is that there is a strong connection between the growth of black holes and the birth of stars. Previously, astronomers had done careful studies of the birth-rate of stars in galaxies, but didn't know as much about the black holes at their centres.

"These galaxies lose material into their central black holes at the same time that they make their stars. So whatever mechanism governs star formation in galaxies also governs black hole growth" - Amy Barger

Source (http://chandra.harvard.edu/press/05_releases/press_021505.html)

Leafguy
2006-Aug-28, 07:26 AM
Basically black holes will grow larger in younger galaxies where there is still a lot of debris left to either develop or be swallowed. Although the size of the galaxy should also determine how large a black hole can grow.

antoniseb
2006-Aug-28, 01:57 PM
Basically black holes will grow larger in younger galaxies where there is still a lot of debris left to either develop or be swallowed. Although the size of the galaxy should also determine how large a black hole can grow.

I'm not sure what you're trying to say here. Are you saying that there are a lot of young galaxies around that will be creating and feeding their central black holes soon? I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe. I also think that only a small fraction of these have been increased via merger since that time as well.

bernardz
2006-Aug-29, 01:44 AM
It would greatly reduce the potential numbers for extraterrestrial intelligence that could be found. Most of the galaxy by number of stars is probably off limits.

RussT
2006-Aug-30, 11:17 AM
I'm not sure what you're trying to say here. Are you saying that there are a lot of young galaxies around that will be creating and feeding their central black holes soon? I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe. I also think that only a small fraction of these have been increased via merger since that time as well.

[I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe.]

Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

antoniseb
2006-Aug-30, 11:59 AM
Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

Yes, maybe sooner. That is not to say that they haven't matured since then...

RussT
2006-Aug-30, 10:30 PM
Then please explain how that is consistent with these!

http://www.narrabri.atnf.csiro.au/public/images/ngc2915/

http://www.astro.uni-bonn.de/~webgk/ws98/thuan_r.html

Just for a start.

antoniseb
2006-Aug-30, 10:57 PM
Then please explain how that is consistent with these!

Low luminosity galaxies, and new dwarf galaxies are not the large galaxies with SMBHs in their centers, so while it is interesting that these things are forming (the 'ghost' galaxy near the edge of a void BTW) they don't contradict my position.

A recent study that DOES somewhat undermine my position is one that plots the mass of dense star clusters in the centers of smaller galaxies alongside of the masses of SMBHs. I don't think this is a killing blow, but it is interesting to me.

RussT
2006-Aug-31, 12:02 AM
Low luminosity galaxies, and new dwarf galaxies are not the large galaxies with SMBHs in their centers, so while it is interesting that these things are forming (the 'ghost' galaxy near the edge of a void BTW) they don't contradict my position.

A recent study that DOES somewhat undermine my position is one that plots the mass of dense star clusters in the centers of smaller galaxies alongside of the masses of SMBHs. I don't think this is a killing blow, but it is interesting to me.


First of all the Ghost Galaxy is classified as a BCD, but it sure looks like (I know, the 'ol 'looks like' arguemment, but this one is VERY hard to deny!)
a full spiral galaxy, it's just that only the core has started the star making process so far!
Second, do you think there is a SMBH in the core that is lit up? I DO!!!

But, as I said, that was just the beginning, what about these???

http://www.xs4all.nl/~carlkop/backyard.html


http://vizier.u-strasbg.fr/cgi-bin/Cat?J/AJ/106/530/table5

And this just simply draws the wrong conclusions, that these galaxies have existed for a very long period of time, and that 'somehow' they have just not had the same level of star formation that the HSB's have had.

That's not it. HSB's used to be just like these, and galaxies DO NOT need any other galaxy interaction to evolve from these to HSB's.

antoniseb
2006-Aug-31, 01:09 AM
HSB's used to be just like these, and galaxies DO NOT need any other galaxy interaction to evolve from these to HSB's.

That might be your opinion, and you might find scientists who agree with you, but you certainly haven't shown anything to back up this statement.

LSBs are found on the edge of voids. I take that to mean that they have a deficit of something that causes the condensation and star-forming, but have just enough that they are barely visible now. Galaxies like the Milky Way formed much more rapidly. Even if you can form some parallels in the formation process, different things were possible in the rapid formation than in this slow accumulation. The creation of an SMBH is probably one of them, and certainly is one of them in my model.

RussT
2006-Aug-31, 10:59 AM
That might be your opinion, and you might find scientists who agree with you, but you certainly haven't shown anything to back up this statement.

LSBs are found on the edge of voids. I take that to mean that they have a deficit of something that causes the condensation and star-forming, but have just enough that they are barely visible now. Galaxies like the Milky Way formed much more rapidly. Even if you can form some parallels in the formation process, different things were possible in the rapid formation than in this slow accumulation. The creation of an SMBH is probably opne of them, and certainly is one of them in my model.


You are correct that I should have included something like...it certainly appears that such and such, etc

[but you certainly haven't shown anything to back up this statement.]

Are you at least skimming the papers I am linking?

They are showing 'new' galaxies, with no interaction, and no hint of merger to have come to their very early stage of developement.

Here is another VERY interseting one.
http://www.citebase.org/abstract?id=oai:arXiv.org:astro-ph/0406505

antoniseb
2006-Aug-31, 12:26 PM
Are you at least skimming the papers I am linking?

I've been reading the abstracts in the cases of papers, and reading the blurb in the cases of short articles and web-sites. I've been interested in LSB galaxies since the first time I saw an article about them, but they are not the same as the HSB galaxies. We can see how HSBs looked less than a billion years after the beginning of the universe, and they were bright with mottles of giant star forming regions, supplied by dense clouds of hydrogen. The LSBs are slowly and much less violently getting themselves together.

LSB galaxies are very interesting, and will, I am sure, be very useful in telling us about the cosmic voids between super-clusters, and perhaps about the first creation of structure in the universe and the distribution of dark matter. You cannot, however claim they are forming the same way our galaxy did.

RussT
2006-Sep-02, 08:26 AM
I've been reading the abstracts in the cases of papers, and reading the blurb in the cases of short articles and web-sites. I've been interested in LSB galaxies since the first time I saw an article about them, but they are not the same as the HSB galaxies.

[I've been interested in LSB galaxies since the first time I saw an article about them,]

Very Good.

[but they are not the same as the HSB galaxies.]

You are right, at least not yet, it is just a matter of evolving to their stages, which of course takes billions of years.



We can see how HSBs looked less than a billion years after the beginning of the universe

Don't you find it interesting, that when they see under-developed galaxies at around a billion years or 'less' "OF THE BEGINNING OF THE UNIVERSE", they immediately start talking about seeing galaxies in their initial stages of developement, BUT when they see a HSB...a MW or M31 type galaxy at the same basic distance (which should be what, 10 to 12 billion years old), they just say we need to figure out how galaxies could have evolved to that stage so soon, and leave it at that.

With all the new LSBs and other Dwarfs (and remember the Ghost galaxy, that is categorized a BCD but surely looks like a spiral) that have been found, near by, in the last decade, has anyone that you know of, actually done any kind of calculation to show how much mass in galaxies and dwarf galaxies, say within 1 billion light years, and then applied the Cosmological Principle to that, and come up with what that would mean to the universe as a whole?



You cannot, however claim they are forming the same way our galaxy did.

So, this would be your opinion then?

Sure I can, and have http://www.bautforum.com/report.php?p=751413

antoniseb
2006-Sep-02, 01:03 PM
Don't you find it interesting, that when they see under-developed galaxies at around a billion years or 'less' "OF THE BEGINNING OF THE UNIVERSE", they immediately start talking about seeing galaxies in their initial stages of developement, BUT when they see a HSB...a MW or M31 type galaxy at the same basic distance (which should be what, 10 to 12 billion years old), they just say we need to figure out how galaxies could have evolved to that stage so soon, and leave it at that.

Be careful who "they" are. I believe that it is perfectly consistant with the model I've been thinking has the best chance of being right over the last four years or so. In this model, the giant ellipticals reach maturity *very* early, and the Milky Way sized galaxies start looking young but formed (i.e. having a lot of star formation) from 0.5 to 1.5 billion years after the universe starts, and everything else happens more slowly.

As I have said above, LSBs are forming on the edge of the voids, and lack *something* that caused the rapid creation of the galaxies we are more familiar with. I suspect that something is the concentration of mass required to form lots of stars in a small area.

You seem to be trying to say that the LSB is just an early form of a mature HSB as we know them now. Either you are saying that a) LSBs are evidence that the universe is infinitely old, in which case you are making an ATM argument, and we should move these posts, or b) that LSBs are just like spiral HSBs, except for some reason we can ignore 'just like' involve developing at 2 to 5 percent the rate of the normal ones.

Which is it?

RussT
2006-Sep-06, 12:20 AM
Be careful who "they" are. I believe that it is perfectly consistant with the model I've been thinking has the best chance of being right over the last four years or so. In this model, the giant ellipticals reach maturity *very* early, and the Milky Way sized galaxies start looking young but formed (i.e. having a lot of star formation) from 0.5 to 1.5 billion years after the universe starts, and everything else happens more slowly.

Yes, this is a bit ATM itself, isn't it? Are we throwing out the Cosmological Principle, and invoking 'different' time parameters for different parts of the universe?



As I have said above, LSBs are forming on the edge of the voids, and lack *something* that caused the rapid creation of the galaxies we are more familiar with. I suspect that something is the concentration of mass required to form lots of stars in a small area.

I am not so sure that all LSB's are formed at the edge of the voids. I'll see what I can find on that. I do know though, that a fairly extensive study was done on BCD's (which are basically, LSB's also) near the voids and in rich clusters, and no discernable difference was detected, and in addition it was also quite a problem that there were no 'quiet' BCD's to be found anywhere!



You seem to be trying to say that the LSB is just an early form of a mature HSB as we know them now. Either you are saying that a) LSBs are evidence that the universe is infinitely old, in which case you are making an ATM argument, and we should move these posts, or b) that LSBs are just like spiral HSBs, except for some reason we can ignore 'just like' involve developing at 2 to 5 percent the rate of the normal ones.

[LSBs are evidence that the universe is infinitely old,]

I never said or implied anything about the universe being infinately old! Those are your words and your assumption.

[b) that LSBs are just like spiral HSBs, except for some reason we can ignore 'just like' involve developing at 2 to 5 percent the rate of the normal ones.]

You also have an assumption in here that is 'yours'.

However, you are correct that this is not the right place to be saying anything 'different', so I will stop doing it that way, and just start asking you more questions, so you can try and show how they can be squared with current thinking.

Lets start with this...Please show how the concept of 'old globular clusters' are normally seen in the DM halos of galaxies, can be seen here.

http://www.narrabri.atnf.csiro.au/public/images/ngc2915/

antoniseb
2006-Sep-06, 12:54 PM
Are we throwing out the Cosmological Principle, and invoking 'different' time parameters for different parts of the universe?

Please show how the concept of 'old globular clusters' are normally seen in the DM halos of galaxies, can be seen here.

To the first part, no, there is no need to invoke different time parameters. As a comparable idea (but not completely a reliable analogy), very heavy stars complete their time on the main sequence in a few million years (maybe less), whereas smaller stars in the same star forming region may not even be settled into the main sequence until after their heavy brethren are black holes or cooling neutron stars. What is the difference? I'm guessing it is a combination of density of available material, and a lack of angular momentum in the medium. Some of these same ideas work in the creation of proto-galaxies, and their subsequent speed of development into mature galaxies.

Now, to the second question: I don't know exactly what you mean. Old globular clusters are in the halos where they are not often disturbed and shreaded by the inner galaxy. I think the fact that they are also in the dark matter halo may be a coincidence. If you ask me a more detailed question, I might be able to give you a better answer.

RussT
2006-Sep-08, 07:33 AM
Quote:
Originally Posted by RussT
Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

Quote:
Orginally Posted by antoniseb #9 above
Yes, maybe sooner. That is not to say that they haven't matured since then...



Lets start with this...Please show how the concept of 'old globular clusters' are normally seen in the DM halos of galaxies, can be seen here.

http://www.narrabri.atnf.csiro.au/pu...mages/ngc2915/

So, since this was formed in the 1st 1 billion years or sooner, by your own statement, then where is the evidence of 'old globular clusters', any type of 'proto galaxy' with its already formed stars, or any type of merger scenario that can be seen to be responsible for the formation of this galaxy?

antoniseb
2006-Sep-08, 02:28 PM
So, since this was formed in the 1st 1 billion years or sooner, by your own statement, then where is the evidence of 'old globular clusters', any type of 'proto galaxy' with its already formed stars, or any type of merger scenario that can be seen to be responsible for the formation of this galaxy?

I can't parse your question as a sentence, so I don't know what you're asking me for. The model I am talking about includes creating (concentrating) the globs of gas that formed the old globular clusters during the galaxy formation process. The model doesn't claim to be refined enough yet to say whether these were ejected from the process of creating the central black hole, or whether they formed simply from the infall of material. It is not very directly connected to the dark matter halo, that you mentioned in the previous post.

RussT
2006-Sep-11, 09:39 AM
The model I am talking about includes creating (concentrating) the globs of gas that formed the old globular clusters during the galaxy formation process.

Right, and by your own statement that I showed above, this was in the 1st 1 billion years.
And, the oldest globular clusters in the Milky Way are in the halo and "as old as our galaxy", right? So there was no "Ejection" (sounds Arpian to me), they are still there! So obviously, the forming of our SMBH did not eject our 'old' globular clusters!

http://www.narrabri.atnf.csiro.au/pu...mages/ngc2915/
So where are the "OLD" globular clusters in this galaxy that your are saying 'should' have formed 12 billion yeras ago??? Where are the Proto-Galaxies with the already formed stars 'merging', like in Carlos Frenk's simulation?

antoniseb
2006-Sep-11, 12:21 PM
Right, and by your own statement that I showed above, this was in the 1st 1 billion years.
And, the oldest globular clusters in the Milky Way are in the halo and "as old as our galaxy", right? So there was no "Ejection" (sounds Arpian to me), they are still there! So obviously, the forming of our SMBH did not eject our 'old' globular clusters!

I'm not sure I'm following your argument. The formation process of the central black hole in the models I'm talking about was fairly brief. Anything that happened during that time would appear (within our ability to measure based on apparent star ages) to be about the same age. You seem to be saying that we have precise ages for both the globular clusters and the galaxy as a whole. I'm saying that both happened at about the same time, within our ability to measure now, but that the sequence of events almost certainly included the formation of the 3 million solar mass black hole early in the process, and large amounts of matter being inhomogenously blasted out of that SMBH forming process (more like the creation of a planetary nebula than something Arpian (to use your term)). The things being blasted out did not have enough energy to escape the new galaxy's gravity. BTW, the several related models aren't refined enough to say if the globular clusters formed before, during, or after the old stars that make up the central bulge of the galaxy.


http://www.narrabri.atnf.csiro.au/pu...mages/ngc2915/
So where are the "OLD" globular clusters in this galaxy that your are saying 'should' have formed 12 billion yeras ago??? Where are the Proto-Galaxies with the already formed stars 'merging', like in Carlos Frenk's simulation?
The link is broken, so I don't know what you're talking about. Personally, I don't claim that galaxies acquire most of their mass from merging protogalaxies (obviously some do, but what fraction?). NGC2915 is a bit of an unusual galaxy, and I haven't taken time to read papers detailing all the ideas about why it might be different. The images I've seen don't prove to me that it doesn't have globular clusters.

neilzero
2006-Sep-11, 12:25 PM
A generalist is someone who attemps to be knowlegeable about many disaplines of science and engineering, but apparently most of you think you can understand individual trees without any understanding of the forest, otherwise you would explain the thousands of abrieviations which you use, many of which have radically different meaning in building construction, politics, electronics, chemistry and quantum mechanics.
It is reasonable that the shape of an SG = spiral galaxy is quite different after an extensive collision with another large galaxy of any type. Neil

antoniseb
2006-Sep-11, 12:46 PM
you would explain the thousands of abrieviations which you use

Sorry for any confusion Neil. Here's a list of the abbreviations used so far in this thread:
11: SMBH - Super Massive Black Hole - refers to the central black hole in a large galaxy.
BTW - By the way - internet shorthand.

12: BCD - Blue Compact Dwarf - a type of galaxy only recently being studied. NGC2915 appears to be one, but in the right light, a large dim seeming spiral structure (or at least a disk) can be seen surrounding its blue core.
HSB - High Surface Brightness - what we think of as a normal galaxy, whether spiral or elliptical.

13: LSB - Low Surface Brightness - A recently discovered type of galaxy seen near the edges of voids. They are large in volume, but don't have many stars.

16: MW - Milky Way - Our galaxy.
M31 - The Andromeda Galaxy - our close neighbor.

17: ATM - Against The Mainstream - refers to a section of this forum where alternative cosmologies (and other ideas are analyzed). These alternatives cannot be discussed in the main section of the forum.

18: DM - Dark Matter - refers specifically to the dark matter which is in galaxy clusters, and in this thread more specifically, that makes up the mass around galaxies called galactic halos (something of a misnomer, since these halos aren't a ring, or shell, but rather permeate the entire galaxy, concentrated at the center.

RussT
2006-Sep-13, 08:46 AM
So where are the "OLD" globular clusters in this galaxy that your are saying 'should' have formed 12 billion years ago??? Where are the Proto-Galaxies with the already formed stars 'merging', like in Carlos Frenk's simulation?

Here is the fixed link.
http://www.narrabri.atnf.csiro.au/public/images/ngc2915/

In post 21 you said;
[The model I am talking about includes creating (concentrating) the globs of gas that formed the old globular clusters during the galaxy formation process.]

In post 19 you said;
[Old globular clusters are in the halos where they are not often disturbed and shreaded by the inner galaxy.]

So, where are the old globular clusters in the halo of the above galaxy, that by your own statement should have formed 12+ billions yeras ago?



You seem to be saying that we have precise ages for both the globular clusters and the galaxy as a whole.

Yes, well the oldest globular cluster(s) that we can get a pretty accurate measurement on are in the halo of the Milky Way, right, and they are pretty much the same age as the galaxy, and not older than the universe!



but that the sequence of events almost certainly included the formation of the 3 million solar mass black hole early in the process, and large amounts of matter being inhomogenously blasted out of that SMBH forming process (more like the creation of a planetary nebula than something Arpian (to use your term)).

If you are suggesting that the creation of the masive black hole is responsible for the flat disc structure of the galaxy (like in a planetary nebula), I agree!



The things being blasted out did not have enough energy to escape the new galaxy's gravity.

And then you say this...but above (post 21) you say...The model I am talking about includes creating (concentrating) the globs of gas that formed the old globular clusters during the galaxy formation process. The model doesn't claim to be refined enough yet to say whether these were ejected from the process of creating the central black hole, My bold.

[QUOTE=antoniseb]
Personally, I don't claim that galaxies acquire most of their mass from merging protogalaxies[.QUOTE]

You have used the term 'in my model' and now 'personally', and also, 'in the several models', and since this is not Q&A, it would seem that any discussion, especially since we seem to be the only ones having it, should be somewhat more relaxed, to include some alternative possiblilities as to how some of these things might make more sense, since we still don't even know which came first, the chicken or the egg.

Anyway, we can explore LSB's and BCD's further if you are open to it.

antoniseb
2006-Sep-13, 12:42 PM
In post 21 you said;
[The model I am talking about includes creating (concentrating) the globs of gas that formed the old globular clusters during the galaxy formation process.]

In post 19 you said;
[Old globular clusters are in the halos where they are not often disturbed and shreaded by the inner galaxy.]

So, where are the old globular clusters in the halo of the above galaxy, that by your own statement should have formed 12+ billions yeras ago?

You seem to be ignoring my statemnts that LSB galaxies (and BCD galaxies) are not like the massive galaxies that formed in the first billion years. Where are the old globular clusters you ask? I ask: Where is the central bulge? How large is the central SMBH? If there are numerous old globular clusters in the extremities of this ghost galaxy, then the process I'm talking about is wrong.

If you are suggesting that the creation of the masive black hole is responsible for the flat disc structure of the galaxy (like in a planetary nebula), I agree!
No, I'm not saying that (though I also don't exlcude that entirely). It is the creation of the central bulge that these models say are part of the process that creates the SMBH. The formation of the disk structure is something that I haven't seen a model for that I'm happy with yet, but paralleling the creation of protoplanetary disks is one viable candidate.

The creation of the globular clusters is not consistant across all models in this family. Looking for smaller, lower-energy parallels I see in detailed images of planetary nebulae inhomgenous clumps that seem to be streaming out through the nebula. There is also a recent study of Eta Carina which discusses the inhomegenous globs in the humonculus nebula that surrounds it. Both of these are from massive energy sources blowing off their outer layers. On the scale of an SMBH forming, those globs could well be sufficiently large to form globular clusters. Did it happen that way? The models in this family disagree with each other.

any discussion... should be somewhat more relaxed, to include some alternative possiblilities as to how some of these things might make more sense
I'm OK with that, though if you want to get really alternative, we should do it where such alternatives can be discussed. The difficulty we need to overcome is that the alternatives I'm talking about are all within the mainstream. You have some interest in some ATM models. We can have the discussion if both parties are aware that BCDs, LSBs, and the details of galaxy formation are not fully understood, and even the main ATM theories have at best incomplete explanations. If we get shown that something can't work, we should agree and move on to other exploration. If we just don't know, or if something is outside the predictions of a model, we should just say so, and move on. I get very bored with ATM discussions that try to dodge these things when there's no need to.

BTW, here's a paper today about a model for Galaxy disk formation:
http://arxiv.org/PS_cache/astro-ph/pdf/0609/0609326.pdf

RussT
2006-Sep-14, 10:06 AM
You seem to be ignoring my statemnts that LSB galaxies (and BCD galaxies) are not like the massive galaxies that formed in the first billion years.

On the contrary, without going ATM, I am trying to ask you about the mainstream models of galaxy formation that show good observational evidence for what I am pointing out.



Where are the old globular clusters you ask? I ask: Where is the central bulge? How large is the central SMBH?

Precisely, if this galaxy formed 12 billion years ago as your statement above says, then where are they?

If you look closely at the picture for a minute (please, look again), you will see where the 'bulge' will be, in fact you can see where the 'bar' will be, and where the stars in the spiral arms will be!

[It is the creation of the central bulge]

And how do they say these are created?
How was the blue core of the Ghost Galaxy created?

[The formation of the disk structure is something that I haven't seen a model for that I'm happy with yet, but paralleling the creation of protoplanetary disks is one viable candidate.]

Yes, it certainly suggests that they were both due to a single event scenario, doesn't it?


We can have the discussion if both parties are aware that BCDs, LSBs, and the details of galaxy formation are not fully understood, and even the main ATM theories have at best incomplete explanations. If we get shown that something can't work, we should agree and move on to other exploration. If we just don't know, or if something is outside the predictions of a model, we should just say so, and move on. I get very bored with ATM discussions that try to dodge these things when there's no need to.

I agree, and hope that the things that I tend to point out will be far from boring.

antoniseb
2006-Sep-14, 12:23 PM
Precisely, if this galaxy formed 12 billion years ago as your statement above says, then where are they?
My statement, if applied to this galaxy, says that it formed 13 billion years go. However, I have maintained that LSBs are different from the galaxies I've been saying formed early. It is different because it is forming very slowly, and perhaps recently, and because the density of the collapsing material is far less than that in galaxies that formed rapidly.

We are at something of an impass because you want to claim that this galaxy is the same as the Milky Way in more ways than I am willing to agree to. I am saying it is different from the Milky Way in ways that you won't acknowledge.

The truth of the matter is that we have some limited observations and studies of this object (and similar objects) and that future observations will certainly be fruitful in explaining some things about the distribution of matter (dark and otherwise) and perhaps also dark energy throughout the local universe. The model I am describing is consistant with mainstream cosmology. You are looking for a model that says that this object violates mainstream cosmology. Do you have more evidence than what it looks like to you?

RussT
2006-Sep-15, 10:49 AM
Well, again, since this isn't Q&A or ATM, it's just Astronomy, and I thought we had just agreed to talk about different aspects of galaxy formation of LSB's abd BCD's and see where it led.

[My statement, if applied to this galaxy, says that it formed 13 billion years go.]
[It is different because it is forming very slowly, and perhaps recently]

Yes, I understand that you are saying they are forming near voids and more slowly, and that I am suggesting a different reason for their 'very low' star formation thus far, but shouldn't there be a consistency to the story of how they formed? The two statements above don't quite gibe, and if i made them, I am sure you would be asking me some questions about them, right?

http://arxiv.org/abs/astro-ph/0502311

Here is another I am ure you will find intesting.

antoniseb
2006-Sep-15, 01:55 PM
shouldn't there be a consistency to the story of how they formed? The two statements above don't quite gibe

I don't see how the two statements don't gibe. Can you elaborate? Also, how consistent do you think the story should be between how LSBs and HSBs form? If they are exactly the same, why don't they look exactly the same? This is strong evidence that there are *some* differences.

BTW, the paper you linked to suggests that the blue LSB galaxies have only recently gotten to the point of ramping up star formation. I don't think that says anything definitive about when the gas that is forming it began to draw together. Could be recent, could be from the beginning.

RussT
2006-Sep-16, 07:56 PM
If we get shown that something can't work, we should agree and move on to other exploration. If we just don't know, or if something is outside the predictions of a model, we should just say so, and move on. I get very bored with ATM discussions that try to dodge these things when there's no need to.

RussT says, as gently as possible! This does work both ways...

[My statement, if applied to this galaxy, says that it formed 13 billion years go.]
[It is different because it is forming very slowly, and perhaps recently]

Your first line in brackets was way earlier in this thread and was pretty clear, and now you are hedging and saying...[and perhaps recently]. If I made those two statements, I am sure you would call me on it!



Also, how consistent do you think the story should be between how LSBs and HSBs form?

Why wouldn't the answer to this be 100%. We either know how galaxies form or we are guessing!



If they are exactly the same, why don't they look exactly the same? This is strong evidence that there are *some* differences.

At first you said that these galaxies should have formed 12 to 13 billion years ago...but if that is the case, then it has taken this long for LSB's and BCD's to start forming their stars, and more and more evidence is showing this to be very difficult to justify! So, more and more papers are starting to surface, hedging the first diagnosis, and saying what you intimated above, that these might be forming in the recent past (from primordial gases), and without going to ATM here, this will be shown to be an even bigger problem!




BTW, the paper you linked to suggests that the blue LSB galaxies have only recently gotten to the point of ramping up star formation. I don't think that says anything definitive about when the gas that is forming it began to draw together. Could be recent, could be from the beginning.


Yes, and it also says this;

"This, in combination with low ages, could constitute a problem for current hierarchical models of galaxy formation, which predict objects of this mass to form predominantly early in the history of the universe".

antoniseb
2006-Sep-17, 04:51 PM
RussT says, as gently as possible! This does work both ways...

[My statement, if applied to this galaxy, says that it formed 13 billion years go.]
[It is different because it is forming very slowly, and perhaps recently]

Your first line in brackets was way earlier in this thread and was pretty clear, and now you are hedging and saying...[and perhaps recently]. If I made those two statements, I am sure you would call me on it!

My first statement was saying that something YOU said, if applied to THIS galaxy would imply that it formed 13 billion years ago. *I* did not say the galaxy formed 13 billion years ago, and *I* am not hedging my bets. I also don't see how you could have read that into what I wrote.


Why wouldn't the answer to this be 100%. We either know how galaxies form or we are guessing!
We don't know how they form entirely, and there is some guessing, but clearly there is something different about LSBs and HSBs. How could the be 100% alike and still be so different?


At first you said that these galaxies should have formed 12 to 13 billion years ago...
I never said that. You are misinterpreting my writing. I said that the Milky Way and M31, and other large bright galaxies formed 13 billion years ago, and have consistantly said that the LSBs are different.

RussT
2006-Sep-18, 04:14 AM
I am really not trying to be difficult here antoniseb, but let's go back to the begining.



Quote:Post #6
Originally Posted by Leafguy
Basically black holes will grow larger in younger galaxies where there is still a lot of debris left to either develop or be swallowed. Although the size of the galaxy should also determine how large a black hole can grow.


I'm not sure what you're trying to say here. Are you saying that there are a lot of young galaxies around that will be creating and feeding their central black holes soon? I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe. I also think that only a small fraction of these have been increased via merger since that time as well.



[I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe.]

Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

And


Quote:
Originally Posted by RussT
Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?


Yes, maybe sooner. That is not to say that they haven't matured since then...


[How could the be 100% alike and still be so different?]

How ATM do you want me to get here? The basic answer is...it depends on what you think is 'different'.

antoniseb
2006-Sep-18, 12:17 PM
Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

Yes, maybe sooner. That is not to say that they haven't matured since then...

The problem here is that I did not read you as meaning *all galaxies* on that post, but rather *all galaxies with SMBHs*. I had previously said that there were numerous galaxies that didn't have SMBHs, including the LMC and SMC, so there was no way I was going to assume you meant *all galaxies*.

RussT
2006-Sep-19, 08:36 AM
The problem here is that I did not read you as meaning *all galaxies* on that post, but rather *all galaxies with SMBHs*. I had previously said that there were numerous galaxies that didn't have SMBHs, including the LMC and SMC, so there was no way I was going to assume you meant *all galaxies*.

Ah, I see.

[but rather *all galaxies with SMBHs*.], which is what I did mean, and I did think we were talking about galaxies (LSB's) and not dwarf galaxies, but numerous dwarf galaxies have been found to have IMBH's, so either way, it's fine with me.

But part of the reason that I have selected the Ghost Galaxy is to be able to discuss these kind of galaxy formation ideas.

http://www.narrabri.atnf.csiro.au/public/images/ngc2915/

So how long ago do you think this was formed, approximately?

And do you think this paper has any validity?

http://www.astro.uni-bonn.de/~webgk/ws98/thuan_r.html

antoniseb
2006-Sep-19, 12:40 PM
So how long ago do you think this was formed, approximately?

I really don't know. LSB galaxies are something I don't have enough information about to have formed an opinion I'm willing to try and defend. These things seem to be forming on the edges of voids, and in the periphery of clusters. Is this a coincidence? They are forming either very late, or very slowly, or (more likely) both. What makes them different from HSBs? I don't know. Do they have less dark matter? Do they have more dark energy? Do they simply have less dense matter? Do they have more angular momentum or less turbulance? Do they have less dust from some unknown early cluster process? Is there some more exotic explanation? All these things are possible, but there just isn't enough information to say what it is yet.


And do you think this paper has any validity?
Well, it's eight years old now. I trust it was written carefully, but our knowledge could well have been corrected, or expanded upon over the last almost a decade. There are papers published pretty often about LSBs and BCDs. I just haven't been reading them beyond the abstracts.

adnanmaniar
2006-Sep-20, 05:09 AM
Hello to ALL,

I am relatively new to this astronomy conversations but its my childhood dream to solve the mystries of this universe.

Coming to this conversation you are having, i am in a favour of focussing on all possibilities regarding the creation of galaxies and role of black holes in it.

Here is one!

It is believed that birth of a galaxy is related to the birth of SMBH. But another possibility is that,
"Birth of a SMBH indicates the begining to an end of galaxy"

There is a balance between the total matter in the galaxy and the number of black holes in it. Any shift of balance will lead to LSB or HSB.

Therefore we should focus ourselves in comparing the number of black holes in LSBs and HSBs.


Here is 2nd,

Every time i see a galaxy, it reminds me of a storm/typhoon. Whereas galaxies are the massive storms of universe.
Since storms are created from low and high pressure, therefore there might be a possibility that galaxies are formed from the cooler dark matter and high energy (unknown).

RussT
2006-Sep-20, 09:25 AM
Hello to ALL,

I am relatively new to this astronomy conversations but its my childhood dream to solve the mystries of this universe.

Coming to this conversation you are having, i am in a favour of focussing on all possibilities regarding the creation of galaxies and role of black holes in it.

Here is one!

It is believed that birth of a galaxy is related to the birth of SMBH. But another possibility is that,
"Birth of a SMBH indicates the begining to an end of galaxy"

There is a balance between the total matter in the galaxy and the number of black holes in it. Any shift of balance will lead to LSB or HSB.

Therefore we should focus ourselves in comparing the number of black holes in LSBs and HSBs.


Here is 2nd,

Every time i see a galaxy, it reminds me of a storm/typhoon. Whereas galaxies are the massive storms of universe.
Since storms are created from low and high pressure, therefore there might be a possibility that galaxies are formed from the cooler dark matter and high energy (unknown).

Welcome to the forum adnanmaniar!

Antoniseb will welcome you soon as well, and give you some pointers on ways to make your time here as enjoyable as possible.

RussT
2006-Sep-20, 09:35 AM
They are forming either very late, or very slowly, or (more likely) both.

Well , if the paper from only eight years ago is correct, and they are forming in the time frames they are suggesting, maybe they aren't evolving as 'slow' as they appear to be because we are comparing them to something that isn't entirely correct.



What makes them different from HSBs?

Just time enough for their stars to fill in all the spiral arms and then inbetween them (and 'pull in' their dwarf galaxies).

antoniseb
2006-Sep-20, 11:47 AM
Antoniseb will welcome you soon as wellYes, Welcome to the forum adnanmaniar!

Every time i see a galaxy, it reminds me of a storm/typhoon.
The shapes certainly have some things in common (that is, spiral galaxies and typhoons), though clearly there are some differences sufficient to say that the meaningfulness of the analogy may not be very deep. Do you have something in mind that is the galactic parallel to the eye-wall (for example)?

antoniseb
2006-Sep-20, 11:57 AM
Well , if the paper from only eight years ago is correct, and they are forming in the time frames they are suggesting, maybe they aren't evolving as 'slow' as they appear to be because we are comparing them to something that isn't entirely correct.

I imagine that the cloud we are seeing began condensing at the same time that the one that formed our galaxy did (though, as noted above, the facts are certainly not all in). This cloud has some property which resulted in a slower production of stars. I listed several possible reasons above. One question is purely semantic: at what point do you say the galaxy began to form? We may not be that far apart in our opinions.

adnanmaniar
2006-Sep-21, 05:00 AM
Thank you for the welcome.

Yes antoniseb, a lot things come in mind but even more questions arises i.e:

Q.1 What is the nucleus of galaxy made up of ?

Q.2 Is it possible that Supergiant Star V838 Monocerotis may become a nucleus of a galaxy in future?

Q.3 Does nebula has something to do with the creation of a galaxy?

Q.4 Is it the Stellar Spire in the Eagle Nebula indicates the begining of a storm/galaxy?

Can you please share some thoughts on it.

RussT
2006-Sep-21, 09:11 AM
I imagine that the cloud we are seeing began condensing at the same time that the one that formed our galaxy did (though, as noted above, the facts are certainly not all in). This cloud has some property which resulted in a slower production of stars. I listed several possible reasons above. One question is purely semantic: at what point do you say the galaxy began to form? We may not be that far apart in our opinions.

Well, I think it has become pretty obvious, that until the question of how the Massive black holes form, the answer to how the galaxies form is pretty much a guesing game.

antoniseb
2006-Sep-21, 11:48 AM
Q.1 What is the nucleus of galaxy made up of ?
Q.2 Is it possible that Supergiant Star V838 Monocerotis may become a nucleus of a galaxy in future?
Q.3 Does nebula has something to do with the creation of a galaxy?
Q.4 Is it the Stellar Spire in the Eagle Nebula indicates the begining of a storm/galaxy?

1. Not all galaxies have what you'd call a nucleus. The Milky Way has a Black Hole that has a mass of about 3 million times the mass of the Sun. That is surrounded closely by another million masses of the Sun (roughly) worth of other material that we don't yet know what it is. It could be some combination of neutron stars, small black holes, dust, and dark matter.

2. No. V838 Mon is just a star. It is part of our galaxy, and will remain so, and has no ability to accumulate the required protogalactic materials to become a galaxy on its own, let alone the motional energy to escape our galaxy.

3. Yes. Nebulas (collectively) are part of the process of galaxy creation and maturation. The specifics are not entirely known, however you can't simply look at any nebula and annonce that it will by itself become a galaxy. The big cloud around the BCD that RussT has linked to will likely become a galaxy, but that is already as big as a galaxy. The Eagle Nebula will not become a galaxy on its own, but will provide numerous new stars for our galaxy.

4. No. It likely will be an open cluster of stars (like the Pleiades) soon (less than a million years).

antoniseb
2006-Sep-21, 11:54 AM
I think it has become pretty obvious, that until the question of how the Massive black holes form, the answer to how the galaxies form is pretty much a guesing game.

I mostly agree. It is possible that the clues we collect might favour learning other parts of the process before we fully understand the SMBH creation process, but I think the odds are that we'll collect more clues about SMBH formation early compared to the rest of the galaxy formation process.

We already have quite a few constraints on what the process must be. I expect us to have a really good framework for how it happens in less than 20 years. The next generation of observing equipment, including the SKA and JWST should make a big difference.

RussT
2006-Sep-22, 09:55 AM
That is surrounded closely by another million masses of the Sun (roughly) worth of other material that we don't yet know what it is.

Thank you very much for this, I had no idea it was this big of number!



I mostly agree. It is possible that the clues we collect might favour learning other parts of the process before we fully understand the SMBH creation process, but I think the odds are that we'll collect more clues about SMBH formation early compared to the rest of the galaxy formation process.

Yes, the more observational constraints we have the better off we are, however I will say that I think it is imperative that all investigation should be as neutral as possible, and let data fall where it may, rather than form fitting it, which I definitely see 'some' tendancy toward, not necessarily for the black holes but for the rest of the galaxy parts and timing.



We already have quite a few constraints on what the process must be. I expect us to have a really good framework for how it happens in less than 20 years. The next generation of observing equipment, including the SKA and JWST should make a big difference.

We have made tremedous strides in the last 10 years (you even questioned the up-to-dateness of the paper I linked from only 8 years ago), so hopefully this happens MUCH sooner than that, especially since Massive Black Holes are much more of a key (to the workings of the universe as well) than anyone is even close to realizing.

adnanmaniar
2006-Sep-22, 09:59 AM
Antoniseb, thank you for the information you provided.

Can we first figure out a way as to how the galaxy is formed?
Let us share and discuss all the possibilities that we have in our mind. GOD knows! maybe we might find a way forward.

Here is what i have in mind.

Imagine a large active region of star formation in Large Magellanic Cloud (LMC) much much bigger than N 180B. These harsh clouds of hydrogen and oxygen swirl and mix with dust and dark matter.
Their intense energy output generates harsh ultraviolet radiation with very strong stellar winds of high speed charged particles that blows across it. The ultraviolet radiation ionizes the interstellar gas and make it glow, "while the wind pierce through the interstellar gas and disperse it".

The piercing of interstellar gas by ultraviolet radiation gives angular motion to each gas parcels partitioning interstellar gas into chunks of interstellar gas indicating that the phonomena can also give birth to two or more galaxies at a time.

These chunks of interstellar gas parcels fall through the potentials of dark matter halos which creates galactic disks.


--------------------------------------------------------------------------

here is some useful link i found when surfing, its not related to above discussion. Its only for the sake of knowledge

http://www.cnn.com/2006/TECH/space/09/21/supernova.reut/index.html

antoniseb
2006-Sep-22, 12:02 PM
maybe we might find a way forward.
Here is what i have in mind...

You'd explain yourself better using diagrams and numbers.

adnanmaniar
2006-Sep-23, 08:27 AM
Imagine a large active region of star formation in Large Magellanic Cloud (LMC) much much bigger than N 180B. These harsh clouds of hydrogen and oxygen swirl and mix with dust and dark matter.
Their intense energy output generates harsh ultraviolet radiation with very strong stellar winds of high speed charged particles that blows across it. The ultraviolet radiation ionizes the interstellar gas and make it glow, "while the wind pierce through the interstellar gas and disperse it".

[Information gathered about LMCs]


The piercing of interstellar gas by ultraviolet radiation gives angular motion to each gas parcels partitioning interstellar gas into chunks of interstellar gas indicating that the phonomena can also give birth to two or more galaxies at a time.

[Only my imagination]


These chunks of interstellar gas parcels fall through the potentials of dark matter halos which creates galactic disks.

[Information comes from "BARYONIC COLLAPSE WITHIN DARK MATTER HALOS
AND THE FORMATION OF GASEOUS GALACTIC DISKS" by Fred C. Adams1,2 and Anthony M. Bloch1,3]

Please share if you guys have some more ideas.

antoniseb
2006-Sep-23, 11:13 AM
These harsh clouds of hydrogen and oxygen swirl and mix with dust and dark matter.
In what way are these clouds harsh?
Your description of the process is all words, and can't really help anyone come to a conclusion. Also, this is actually pretty far removed from the original topic that SMBHs prevent star formation, and the related topic about galaxies with no apparent SMBH (yet).

There's a lot of good stuff on this forum. I suggest reading, posting requests for clarifications, and making suggestions when we hit one of your growing areas of strength.

adnanmaniar
2006-Sep-25, 04:38 AM
Yes antoniseb, here is the link b/w LMC and SMBH.

Please read the first page only
http://homepage.mac.com/stevoss/SAS/page5/files/Dec2005.pdf

SMBH can exists in galaxies as well as in LMCs. Maybe the two things aren't really that far apart.

antoniseb
2006-Sep-25, 11:45 AM
SMBH can exists in galaxies as well as in LMCs. Maybe the two things aren't really that far apart.

I had forgotten this news story, but it does suggest that there is an SMBH (or IMBH) in the LMC.

adnanmaniar
2006-Sep-27, 04:59 AM
Here is a useful paper i found which is related to the creation of SMBH.

http://aanda.u-strasbg.fr:2002/papers/aa/full/2001/36/aadg181/node3.html

Kindly share your thoughts on the above.

BTW where is RUSST?

RussT
2006-Sep-27, 08:42 AM
Here is a useful paper i found which is related to the creation of SMBH.

http://aanda.u-strasbg.fr:2002/papers/aa/full/2001/36/aadg181/node3.html

Kindly share your thoughts on the above.

BTW where is RUSST?

You are new to BAUT, so when I said welcome and that antoniseb would be right along to welcome you also, I expected that he would be explaining a few things, like I said, to make your time here as enjoyable as possible.

So I will let you know of a few rules that exist here.

Q&A section is where you can ask questions and Mainstream answers will be given. Some discussion can take place there, but NO non-mainstream theories or ideas can be touted.

Astronomy and these Universe Today stories also allow discussions and although there is a little more leeway in those discussions, still NO alternative theories can be presented, unless they are what you are kinda doing, just suggesting things.

antoniseb knows that I have an alternative theory, and because of his interest in LSB's, was willing to have a discussion, but has stated that he is only willing to look at galaxy formation from a mainstream viewpoint, our conversation just naturally dwindled as his responses were less and less substantive.

As far as the link above...Martin Rees is one of the most highly respected astronomers in the world, and the date on the front page of that is 1984, and as far as I know (AFAIK), none of the five 'possibilities' (and he seemed to indicate that was all there were that he could think of) has been shown to be the answer.

The question remains one of the biggest in all of cosmology, which came first the chicken or the egg (the galaxy or the SMBH?)

So I cannot give you 'my' answer here.

antoniseb
2006-Sep-27, 10:39 AM
Rees' paper was written in 1984 (22 years ago). We've had some considerable amount of observation since then. This paper that you linked to had some good analysis in it, but the details are still up in the air.

adnanmaniar
2006-Sep-29, 04:33 AM
RUSST "The question remains one of the biggest in all of cosmology, which came first the chicken or the egg (the galaxy or the SMBH?)"

Since moving iron in earths crust in the presence of magnetic field generates current which itself produces magnetic field.

i.e. moving iron->current->magnetism->more moving iron-> more current.....

It doen't matter most which came first. What matters is know the correct cycle w. r. t. galaxies formation. And there must be only one cyclic process which needs some attention.

Antoniseb, thats why i am saying to please share more ideas/papers which you think makes more sense than the others.

antoniseb
2006-Sep-29, 12:05 PM
It doen't matter most which came first. What matters is know the correct cycle w. r. t. galaxies formation. And there must be only one cyclic process which needs some attention.

I'm not sure I know what you mean here. There may be many processes for galaxy formation. It can be affected by the matter density, the angular momentum of the initial material, it might potentially be affected by primordial magnetic fields (which haven't been proven to exist, but neither have they been excluded), local turbulence, dark matter density, and ionization and heavy element seeding from nearby larger proto-galaxies (and probably factors I'm not even thinking of).

RussT and I agree that there is a lot we don't know yet about the topic of galaxy formation, but this is an exciting time because new observations are coming in and setting constraints on the various processes that affect the formation.

RussT has an interest in BCD galaxies, which he thinks are a big clue. I started a thread down in the Astonomy section of the forum to discuss recent papers about BCDs as they come along. They are worth looking at. Look for more discussion there, rather than here.

GOURDHEAD
2006-Sep-29, 01:11 PM
it might potentially be affected by primordial magnetic fields (which haven't been proven to exist, but neither have they been excluded)Proof, like beauty, can be a function of the mind of the beholder. We have not observed any liquid "runing downhill" on any object, other than the earth (maybe lava on Io) but I doubt any of us doubt that it would due to our mindset about the function of gravity. In like manner the first few thousand years (maybe even until now) of the universe was believed to have been sufficiently ionized (probably 100% early on) and thermally agitated to generate electric currents of enormous magnitudes. In such an environment how could 10^40 or so tesla fields have been avoided? This is not proof in the classic sense, but it deserves more recognition that idle speculation--is there a name for this sort of inferential conclusion?

antoniseb
2006-Sep-29, 01:51 PM
In such an environment how could 10^40 or so tesla fields have been avoided?

1040 tesla is a little extreme. It would be interesting to know what the scale of the magnetic field was at 380,000 years after the start of everything (when we see the CMB from).

adnanmaniar
2006-Oct-02, 05:34 AM
Reading the link;
http://www.astro.uni-bonn.de/~webgk/ws98/thuan_r.html

I am not fully satisfied with section 4.4 (Iron)
BCDs have significantly low-metallicity. I wonder from where they will fill this gap!

Although there is a possibility that BCDs are new galaxies.
Please see a useful link;
http://www.spaceref.com/news/viewpr.html?pid=19188

antoniseb
2006-Oct-02, 11:28 AM
BCDs have significantly low-metallicity. I wonder from where they will fill this gap!

BCDs are not under an obligation to fill this gap. They might, in the fullness of time, increase their metalicities to be similar to galaxies we are familiar with today, or they might not. The 1998 paper you cited here is not the most current, but even current papers are reporting new findings and speculating as to what they mean.

adnanmaniar
2006-Oct-03, 04:32 AM
I agree with you antoniseb that they might or might not fill their metallicity.
Which can led them to become LSBs or HSBs???

Please share some thoughts on this paper that says;

"The star formation rates we determine from these galaxies are on the order of 10-3 - 10-2 M yr-1 and that we see no evidence for long gaps in star formation in their recent history".

http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v567n1/54424/54424.text.html

antoniseb
2006-Oct-03, 12:02 PM
Please share some thoughts on this paper
This is a busy week for me. I don't plan to take 3/4 hour to read a five year old paper. I don't mean this as a slight against you or the paper.

Why don't you start by sharing your thoughts on the paper.

adnanmaniar
2006-Oct-04, 04:47 AM
The paper say;
"We present the star formation history of UGCA 290, a galaxy with properties intermediate between blue compact dwarfs (BCDs) and dwarf irregulars."

RUSST suggests that the blue LSB galaxies have only recently gotten to the point of ramping up star formation.

But paper suggests,
"Using synthetic color-magnitude diagrams, we show that the recent "burst" which gives this galaxy its BCD status is a moderate enhancement in star formation which lasted for approximately 20 Myr, at a rate about 10 times above its previous rate. The star formation history for most of the previous billion years is consistent with a constant rate. The traditional picture of intense bursts and long gaps does not seem to apply to nearby BCDs"

You were saying they are forming near voids and more slowly, and perhaps recently.

But paper suggests,
"The star formation rates we determine from these galaxies are on the order of 10-3 to 10-2 M yr-1 and that we see no evidence for long gaps in star formation in their recent history".

RussT
2006-Oct-04, 06:29 AM
RUSST suggests that the blue LSB galaxies have only recently gotten to the point of ramping up star formation.

It's all relative.

1 billion years VS 12 billion years is recent and certainly no galaxy makes all of its stars in a short period of time.

The main point is, let's assume they are right, that it is actually 1 billion years old, (there are some even younger) then where has the DM halo been, where has the gas been (I saw a page on Wiki, that said that HI can only survive for 10 million years, but I haven't been able to find it again) and most importantly, where has the SMBH been, how was it created, are there gases and DM halo's, and SMBH's trying to find each other through the cosmos to start a galaxy....this is a far cry from any of the models that have put forth.

antoniseb
2006-Oct-04, 11:55 AM
...where has the SMBH been, how was it created, are there gases and DM halo's, and SMBH's trying to find each other through the cosmos to start a galaxy...

Are you suggesting some kind of cosmic dating service is required to start a galaxy? The usual understanding is that the SMBH probably is created as part of the initial collapse of the cloud that becomes a large galaxy. However LSBs and BCDs are both forming so slowly that it is possible that no SMBH has formed there. Now, it is also possible that there *is* an SMBH in some or all of these galaxies. A recent paper I pointed to in the BCD thread in the Astronomy section mentions that these galaxies seem to be very dusty, which could be concealling the evidence for an SMBH.

RussT
2006-Oct-04, 09:23 PM
Are you suggesting some kind of cosmic dating service is required to start a galaxy? The usual understanding is that the SMBH probably is created as part of the initial collapse of the cloud that becomes a large galaxy. However LSBs and BCDs are both forming so slowly that it is possible that no SMBH has formed there. Now, it is also possible that there *is* an SMBH in some or all of these galaxies. A recent paper I pointed to in the BCD thread in the Astronomy section mentions that these galaxies seem to be very dusty, which could be concealling the evidence for an SMBH.

[Are you suggesting some kind of cosmic dating service is required to start a galaxy?]

What I am suggesting is that the entire Galaxy Formation paradigms are way out of whack.

[The usual understanding is that the SMBH probably is created as part of the initial collapse of the cloud that becomes a large galaxy.]

Which is one of the many reasons they cannot figure out how SMBH's are created!
Wouldn't you say that it is a *Well Known Fact* that the collapse of hydrogen clouds (dust) or planetary nebula clouds (dust) cause 'star formation'?!
Have you seen any 3 million sol mass 'stars' anywhere in the universe, primordial or otherwise?


[However LSBs and BCDs are both forming so slowly that it is possible that no SMBH has formed there.]

Once again you are assuming time constraints based on preconcieved notions.

They are not 'forming so slowly' if they were recently created.

[A recent paper I pointed to in the BCD thread in the Astronomy section mentions that these galaxies seem to be very dusty, which could be concealling the evidence for an SMBH.]

Yes, and it has become pretty evident 'that they do'!

RussT
2006-Oct-04, 09:31 PM
Are you suggesting some kind of cosmic dating service is required to start a galaxy?

Are you suggesting, that if this galaxy is only 1 billion years old, that the DM halo/SMBH with all the Hydrogen sitting in the DM halo, just sat around for 12 billion years before it started making stars???

antoniseb
2006-Oct-04, 10:03 PM
Are you suggesting, that if this galaxy is only 1 billion years old, that the DM halo/SMBH with all the Hydrogen sitting in the DM halo, just sat around for 12 billion years before it started making stars???

No, I'm surprised that I haven't gotten my point here across. I am saying that there is no certainty that there is an SMBH in this galaxy, and might possibly never be one. As to the Dark Matter halo, I do not regard that as connected to the SMBH. The Dark Matter has been there since the early days of the universe, but I do not know the ratio of Dark Matter to Reactive Matter in the LSBs. I do expect it to be different than the ratio of our galaxy.

RussT
2006-Oct-04, 10:19 PM
No, I'm surprised that I haven't gotten my point here across. I am saying that there is no certainty that there is an SMBH in this galaxy, and might possibly never be one. As to the Dark Matter halo, I do not regard that as connected to the SMBH. The Dark Matter has been there since the early days of the universe, but I do not know the ratio of Dark Matter to Reactive Matter in the LSBs. I do expect it to be different than the ratio of our galaxy.

And you are not seeing my points.

Okay, for now, let's forget about the SMBH.

Are you suggesting that this Hydrogen has just sat around in this dark matter halo for 12 billion years before it started making stars?

antoniseb
2006-Oct-05, 12:58 AM
Are you suggesting that this Hydrogen has just sat around in this dark matter halo for 12 billion years before it started making stars?

Yes, sort of. Our galaxy has used about 20% of its Hydrogen by making stars at a rate of between 1 and 10 Solar masses per year (it was about 10 5 billion years ago, it is closer to 1 now). For some reason the LSB galaxies seem to be making stars at a rate of one star per 100 to 1000 years (based on recent papers about observations).

Are the observations correct? I think there's room for some doubt, but the current view seems to be that the LSBs have been around as long as the other galaxies, but are converting the Hydrogen into stars at a much slower rate. No explanation is given.

adnanmaniar
2006-Oct-05, 04:02 AM
Please see the DISCUSSION AND CONCLUTIONS section of the paper.

The paper say;
"Combining these estimates of the star formation history and total gas content of UGCA 290, we can also address its gas consumption timescale. A very short gas consumption timescale implies that the current level of star formation cannot be maintained for a long period, and is one of the traditional arguments for the unusual nature of BCDs. For UGCA 290, the maximum burst level of 0.04 M yr-1 would take 600 million years to use up its H I gas mass, even at 100% efficiency. In fact, this burst level was maintained for only 15 Myr. The average star formation rate of UGCA 290 over the past billion years, 0.003 M yr-1, could be maintained for over seven billion years. Therefore, UGCA 290 may well continue forming stars in a similar manner for a long time."

However more precise mass estimates, and in particular a solid estimate of the dark matter content, await new observations.

RussT
2006-Oct-05, 08:13 AM
For some reason the LSB galaxies seem to be making stars at a rate of one star per 100 to 1000 years (based on recent papers about observations).

Are the observations correct? I think there's room for some doubt, but the current view seems to be that the LSBs have been around as long as the other galaxies, but are converting the Hydrogen into stars at a much slower rate. No explanation is given.

Well sure, if you just assume they have been around as long as the others, you would come up with those numbers!


What about the BCD's then and this, again.

http://www.astro.uni-bonn.de/~webgk/ws98/thuan_r.html

antoniseb
2006-Oct-05, 10:30 AM
There is a BCD discussion (http://www.bautforum.com/showthread.php?t=47307) I've been trying to start down in the Astronomy section. Can we take this discussion there?

Hamilcar
2006-Oct-23, 11:51 AM
[I'd be surprised if any super-massive black hole has been created since a billion years after the beginning of the universe.]

Are you suggesting that all the galaxies we see today had to be formed with their Massive black holes in their cores, in the first 1 billion years?

That's current thinking. IIRC there has been some work on the high-z M-sigma relation claiming that there's been pretty much no evolution.