Holes in Big Bang

[Reality Check]

FYI, there are new signs that the 'mass estimation techniques' of standard theories will require some revision because they fail to account for some of even the most visible material that is located inside various galaxies:

http://www.sciencedaily.com/releases/2009/08/090819145846.htm

Emphasis mine.

Interesting article on how one technique for measuring the mass of galaxies is being refined.

 

[Michael Mozina]

Interesting article on how one technique for measuring the mass of galaxies is being refined.

Indeed. One wonders about the value of current estimation techniques if they underestimate the number of highly visible stars by a factor of four. The notion of "dark" seems to apply not only to non baryonic matter, but anything under a specific physical size, including even smaller sized suns. It makes the whole notion of SUSY theory that much less plausible, and certainly that much less necessary IMO. They don't even seem to have a good handle yet on the amount of highly visible baryonic material in a galaxy, so why would I believe there is any need for non baryonic forms of matter to explain 'missing mass'?

 

[Reality Check]

Indeed. One wonders about the value of current estimation techniques if they underestimate the number of highly visible stars by a factor of four. The notion of "dark" seems to apply not only to non baryonic matter, but anything under a specific physical size, including even smaller sized suns. It makes the whole notion of SUSY theory that much less plausible, and certainly that much less necessary IMO. They don't even seem to have a good handle yet on the amount of highly visible baryonic material in a galaxy, so why would I believe there is any need for non baryonic forms of matter to explain 'missing mass'?

You misread the article.
The point is that these stars are not "highly visible" and so their numbers were estimated in the past. Current observation techniques have revealed that in some galaxies the smaller mass stars may be miscounted by a factor of 4.

This belief, based on years of research, has been tipped on its side with new data from NASA's Galaxy Evolution Explorer. The ultraviolet telescope has found proof that small stars come in even bigger bundles than previously believed; for example, in some places in the cosmos, about 2,000 low-mass stars may form for each massive star. The little stars were there all along but masked by massive, brighter stars.
....
"Especially in these galaxies that seem small and piddling, there can be a lot more mass in lower mass stars than we had previously expected from what we could see from the brightest, youngest stars," Meurer said. "But we can now reduce these errors using satellites like the Galaxy Evolution Explorer."

(Emphasis mine)

They do have a "good handle" on the mass of the baryonic material in a galaxy. This new observation will allow more accurate estimates of galaxy masses.
A real astronomer could tell us the real error limit in galaxy mass calculations (50%?)

ETA: The actual journal article looks like "Evidence for a Nonuniform Initial Mass Function in the Local Universe".

 

[Michael Mozina]

You misread the article.
The point is that these stars are not "highly visible" and so their numbers were estimated in the past. Current observation techniques have revealed that in some galaxies the smaller mass stars may be miscounted by a factor of 4.

What you're essentially saying is that "previous" observations (at the visible spectrum) were incapable of picking out even highly visible forms of baryonic material, whereas more modern instruments are in fact capable of noticing this omission. What you seem to be ignoring is the fact that current techniques don't account for these modern observations, at least not yet.

(Emphasis mine)

They do have a "good handle" on the mass of the baryonic material in a galaxy. This new observation will allow more accurate estimates of galaxy masses.
A real astronomer could tell us the real error limit in galaxy mass calculations (50%?)

That sounds rather like an underestimate rather than a real number IMO, particularly if they underestimate the number of stars by a factor of four. The point here is that our current technologies haven't even been applied to our mass estimation techniques yet, so why should anyone have 'great faith' that any material is located in SUSY particles if we can't even accurately measure (or haven't accurately factored in) the amount of highly visible stars in a galaxy?

 

[Reality Check]

What you're essentially saying is that "previous" observations (at the visible spectrum) were incapable of picking out even highly visible forms of baryonic material, whereas more modern instruments are in fact capable of noticing this omission. What you seem to be ignoring is the fact that current techniques don't account for these modern observations, at least not yet.

That is right (but I would say throughout the spectrum rather than just visible). That is what the last paragraph of the article states.

That sounds rather like an underestimate rather than a real number IMO, particularly if they underestimate the number of stars by a factor of four. The point here is that our current technologies haven't even been applied to our mass estimation techniques yet, so why should anyone have 'great faith' that any material is located in SUSY particles if we can't even accurately measure (or haven't accurately factored in) the amount of highly visible stars in a galaxy?

It also sounds like a underestimate to me.

As as already been stated to you on many occassions:

We can be confident that dark matter is non baryonic matter beacase

1. The mass estimates are not out by the factors that are needed to account for dark matter.
2. Baryonic dark matter has been looked for and not found (MACHOs).
3. Dark matter acts as if it weakly interacts electromagnetcally (i.e. is non baryonic):
   NASA Finds Direct Proof of Dark Matter (another observation)

ETA:
Make this the three observations aready cited to you in another thread: Bullet Cluster and MACS J0025.4-1222 (and even Abell 520)

 

[Michael Mozina]

That is right (but I would say throughout the spectrum rather than just visible). That is what the last paragraph of the article states.

That really tends to blur the term "dark" doesn't it? I mean it may be "dark" in the visible spectrum relative to our current technologies, but it's not "dark" on every spectrum.

We can be confident that dark matter is non baryonic matter beacase

1. The mass estimates are not out by the factors that are needed to account for dark matter.

1. 
   
   How do you know that? They evidently have underestimated the number of stars in a galaxy by at least a factor of four. My "guess" is that is a relatively 'conservative" number as well.
   
   

   Baryonic dark matter has been looked for and not found

   
   They just found a bunch of baryonic matter! I don't think you like the implications of this article/paper, but it's pretty clear. We haven't accurately estimated the amount of even the number of stars in a galaxy, so the whole notion that non baryonic forms of matter are required to explain "missing mass" is highly suspect. We could and evidently are simply grossly underestimating the amount of normal material in a galaxy. Period.

 

[Reality Check]

How do you know that? They evidently have underestimated the number of stars in a galaxy by at least a factor of four. My "guess" is that is a relatively 'conservative" number as well.

They have just found a bunch os baryonic matter - just not enough. They need factors of 100's of unmeasured stars.

The stars in question are not "dark" matter. They are normal visible matter that is just hard to see in the visible spectum because of the glare from brighter stars and so you have to look in the non-visible spectrum:
Evidence for a Nonuniform Initial Mass Function in the Local Universe

Many of the results in modern astrophysics rest on the notion that the initial mass function (IMF) is universal. Our observations of a sample of H I selected galaxies in the light of Hα and the far-ultraviolet (FUV) challenge this result. The extinction-corrected flux ratio F Hα/f FUV from these two tracers of star formation shows strong correlations with the surface brightness in Hα and the R band: low surface brightness (LSB) galaxies have lower F Hα/f FUV ratios compared to high surface brightness galaxies as well as compared to expectations from equilibrium models of constant star formation rate (SFR) using commonly favored IMF parameters. Weaker but significant correlations of F Hα/f FUV with luminosity, rotational velocity, and dynamical mass as well as a systematic trend with morphology, are found. The correlated variations of F Hα/f FUV with other global parameters are thus part of the larger family of galaxy scaling relations. The F Hα/f FUV correlations cannot be due to residual extinction correction errors, while systematic variations in the star formation history (SFH) cannot explain the trends with both Hα and R surface brightness nor with other global properties. The possibility that LSB galaxies have a higher escape fraction of ionizing photons seems inconsistent with their high gas fraction, and observations of color-magnitude diagrams (CMDs) of a few systems which indicate a real deficit of O stars. The most plausible explanation for the correlations is the systematic variations of the upper mass limit

and/or the slope γ which define the upper end of the IMF. We outline a scenario of pressure driving the correlations by setting the efficiency of the formation of the dense star clusters where the highest mass stars preferentially form. Our results imply that the SFR measured in a galaxy is highly sensitive to the tracer used in the measurement. A nonuniversal IMF would also call into question the interpretation of metal abundance patterns in dwarf galaxies as well as SFHs derived from CMDs.

The impact of this observation on dark matter is minor. The evidence that dark matter is non baryonic matter is strong. The amount of baryonic matter is not increaed enough to account for the amount of dark matter that is observed, e.g. by galactic lensing.

 

[tuc0]

Great tags on this thread! Recent Data shows that if the Big Bag is full of holes stuff (also known as matter) will keep falling out.

 

[DeiRenDopa]

Indeed. One wonders about the value of current estimation techniques if they underestimate the number of highly visible stars by a factor of four. The notion of "dark" seems to apply not only to non baryonic matter, but anything under a specific physical size, including even smaller sized suns. It makes the whole notion of SUSY theory that much less plausible, and certainly that much less necessary IMO. They don't even seem to have a good handle yet on the amount of highly visible baryonic material in a galaxy, so why would I believe there is any need for non baryonic forms of matter to explain 'missing mass'?

You misread the article.
The point is that these stars are not "highly visible" and so their numbers were estimated in the past. Current observation techniques have revealed that in some galaxies the smaller mass stars may be miscounted by a factor of 4.

This belief, based on years of research, has been tipped on its side with new data from NASA's Galaxy Evolution Explorer. The ultraviolet telescope has found proof that small stars come in even bigger bundles than previously believed; for example, in some places in the cosmos, about 2,000 low-mass stars may form for each massive star. The little stars were there all along but masked by massive, brighter stars.
....
"Especially in these galaxies that seem small and piddling, there can be a lot more mass in lower mass stars than we had previously expected from what we could see from the brightest, youngest stars," Meurer said. "But we can now reduce these errors using satellites like the Galaxy Evolution Explorer."

(Emphasis mine)

They do have a "good handle" on the mass of the baryonic material in a galaxy. This new observation will allow more accurate estimates of galaxy masses.
A real astronomer could tell us the real error limit in galaxy mass calculations (50%?)

ETA: The actual journal article looks like "Evidence for a Nonuniform Initial Mass Function in the Local Universe".

Yes, that does seem to be the paper on which the PR is based.

By comparing the paper to the PR, it is easy to see why one should always go to the primary source, especially when trying to draw inferences that are beyond what is stated.

I'll write more about this in later posts, but the techniques used to estimate total mass in galaxies are many and varied, and they give consistent answers (albeit sometimes the uncertainties are big).

Wrt this particular paper, a possible implication concerning the estimated total baryonic mass in a galaxy is: if you use a combo of estimated SFR and IMF to derive a (baryonic) mass estimate, you may have introduced a systematic error; specifically, the IMF for LSBs (low surface brightness) galaxies may be significantly different from the IMF for other galaxies (and even this is too extreme; the paper reports only estimates of the top part of the IMF, specifically O and B stars).

 

[DeiRenDopa]

What you're essentially saying is that "previous" observations (at the visible spectrum) were incapable of picking out even highly visible forms of baryonic material, whereas more modern instruments are in fact capable of noticing this omission. What you seem to be ignoring is the fact that current techniques don't account for these modern observations, at least not yet.

That is right (but I would say throughout the spectrum rather than just visible). That is what the last paragraph of the article states.

I don't know how to even begin addressing this ...

... but here goes.

The relationship between a star's mass and its electromagnetic output (both total energy output and SED, spectral energy distribution) is now quite well understood, and observations of individual stars in a particular galaxy (or part thereof) can use this well-established relationship for a variety of purposes.

One such purpose is to estimate the initial mass function of stars; the distribution of stars, by mass (or luminosity) at birth. Such research has been going on for decades, and consistent results have been obtained for stars in star clusters; however, the extent to which the observed (star cluster) IMF is universal is not well-constrained.

Turning to observations of galaxies.

Except for those in the Local Group, and except for instruments such as the HST, individual stars in galaxies cannot be 'resolved' (caveat: novae and supernovae are exceptions). So the techniques used to estimate the stellar content of these galaxies rely upon observations other than the detection of individual stars (there are several such). What this paper says is that proxies for the number of O stars and the number of B stars (one proxy for each) can be used to estimate the extent to which the top part of the IMF varies between galaxies. This is quite difficult to do - the paper spends many pages discussing the various systematic effects the authors identified and tried to control for, for example - but they make a good case that there is a variation. They also point out that their finding is consistent with what several others have found, using completely different techniques.

Perhaps the most exciting implication of the finding is the possibility of getting a better handle on the extent to which star formation is dependent on environment!

That sounds rather like an underestimate rather than a real number IMO, particularly if they underestimate the number of stars by a factor of four. The point here is that our current technologies haven't even been applied to our mass estimation techniques yet, so why should anyone have 'great faith' that any material is located in SUSY particles if we can't even accurately measure (or haven't accurately factored in) the amount of highly visible stars in a galaxy?

It also sounds like a underestimate to me.

As as already been stated to you on many occassions:

We can be confident that dark matter is non baryonic matter beacase

1. The mass estimates are not out by the factors that are needed to account for dark matter.
2. Baryonic dark matter has been looked for and not found (MACHOs).
3. Dark matter acts as if it weakly interacts electromagnetcally (i.e. is non baryonic):
   NASA Finds Direct Proof of Dark Matter (another observation)

ETA:
Make this the three observations aready cited to you in another thread: Bullet Cluster and MACS J0025.4-1222 (and even Abell 520)

There's so much confusion here!

First, though, the application of an IMF to estimate a galaxy's mass is relatively restricted ... where the IMF is used is in making estimates of the mass-to-light ration (M/L), expressed in sols; specifically, the observed luminosity is used to derive an estimate of the total stellar content, the mass is estimated using techniques that (typically) have nothing to do with the IMF.

Second, studies of different kinds of galaxies (LSB, BCD, dSp, E, ...) tend to give consistent results, wrt the total mass, M/L, and so on.

Third, most of the mass in the observable universe seems to reside in the IGM of clusters of galaxies, not the galaxies themselves, so a change in the estimated mass of the stars in some kinds of galaxies has essentially no impact on larger scales.

I think I'll stop here; I'm probably only making matters more confusing ...

 

[DeiRenDopa]

How do you know that? They evidently have underestimated the number of stars in a galaxy by at least a factor of four. My "guess" is that is a relatively 'conservative" number as well.

They have just found a bunch os baryonic matter - just not enough. They need factors of 100's of unmeasured stars.

We are now so far from what the paper says that I see no point in commenting ... except to say that if anyone is interested, I'd be happy to walk them through the paper, paying particular attention to what it actually says (and not what implications you think you can read into it).

In a nutshell, the paper's direct implications have to do with estimating SFRs (star formation rates) in one class of rather poorly understood galaxies (LSBs) ... and the authors discuss this in Section 6.3; the extent to which variations in the top end of the IMF between galaxies impacts estimates of the baryonic content of those galaxies is not discussed in the paper (and rightly so too).

[...]


The impact of this observation on dark matter is minor. The evidence that dark matter is non baryonic matter is strong. The amount of baryonic matter is not increaed enough to account for the amount of dark matter that is observed, e.g. by galactic lensing.

Indeed.

One of the extraordinary things about CDM is the breadth of its explanatory power.

 

[Michael Mozina]

The relationship between a star's mass and its electromagnetic output (both total energy output and SED, spectral energy distribution) is now quite well understood,....

I'm sorry, but when you say this kind of thing after that kind of revelation, it's really hard to take you seriously anymore.

http://www.spaceref.com/news/viewpr.html?pid=25444

Dr Driver said, "You can't get more energy out than you put in so we knew something was very wrong. Even so, the scale of the dust problem has come as a shock appears that galaxies generate twice as much starlight as previously thought."

The team combined an innovative new model of the dust distribution in galaxies developed by Dr Cristina Popescu of the University of Central Lancashire and Prof Richard Tuffs of the Max Plank Institute for Nuclear Physics, with data from the Millennium Galaxy Catalogue, a state-of-the-art high resolution catalogue of 10,000 galaxies assembled by Driver and his team using the Isaac Newton Telescope on La Palma among others.

Using the new model, the astronomers could calculate precisely the fraction of starlight blocked by the dust. The key test that the new model passed was whether the energy of the absorbed starlight equated to that detected from the glowing dust.

"The equation balanced perfectly", said Dr Cristina Popescu, "and for the first time we have a total understanding of the energy output of the Universe over a monumental wavelength range."

"The results demonstrate very clearly that interstellar dust grains have a devastating effect on our measurements of the energy output from even nearby galaxies" says Prof Richard Tuffs, "with the new calibrated model in hand we can now calculate precisely the fraction of starlight blocked by the dust."

In just the last year and a half, we have discovered that the galaxies are shining twice as brightly as we once thought (way more starlight), the number of small mass stars is four times what we first believed, we're still "missing" most of the mass of a galaxy, and you now want me to believe that we have these things all figured out and everything is 'well understood'. Please. Your statements simply don't jive with reality.

I have no doubt that we *THOUGHT* these relationships were well understood, but clearly they are not as simple as we believed, and a lot of that 'missing mass' isn't found in "dark matter', but in the form of actual stars in the galaxy. How exactly did you expect the stars to shine twice and brightly without increasing the mass of the galaxy?

It seems to me that if we haven't correctly identified even something as visually obvious as a star, or the amount of starlight coming from a galaxy, then there is really no reason to believe that our mass estimation techniques are currently worth the paper they are printed on. A quick glance at the lensing data verifies that we have grossly underestimated the standard mass of a galaxy and these two papers explain at least part of the problems with our mass estimation techniques. They are based on *MANY* different assumptions, some of which are evidently way off.

 

[Skwinty]

We are now so far from what the paper says that I see no point in commenting ... except to say that if anyone is interested, I'd be happy to walk them through the paper, paying particular attention to what it actually says (and not what implications you think you can read into it).

Yes please.

In a nutshell, the paper's direct implications have to do with estimating SFRs (star formation rates) in one class of rather poorly understood galaxies (LSBs) ... and the authors discuss this in Section 6.3; the extent to which variations in the top end of the IMF between galaxies impacts estimates of the baryonic content of those galaxies is not discussed in the paper (and rightly so too).

Please expand these two bolded acronyms. Thanks for the illuminating posts.

 

[DeiRenDopa]

LSB = low surface brightness (galaxies)
IMF = initial mass function.

Do you have a copy of the paper to hand Skwinty? It doesn't have to be what was actually published in ApJ, arXiv:0902.0384v2 will do.

If so, let's start with the Summary (section 7); if not, please get one (and let me know when you have it).

 

[Skwinty]

LSB = low surface brightness (galaxies)
IMF = initial mass function.

Thanks, now that I have the correct paper, I can see my question was rather shortsighted.

 

[DeiRenDopa]

Thanks, now that I have the correct paper, I can see my question was rather shortsighted.

No worries.

Why not take some time to read, or at least skim, the paper first? As I said, perhaps a good way to go through it is to go through the Summary, point by point; however, you may get more understanding by asking questions directly (your choice! ).

 

[Skwinty]

Why not take some time to read, or at least skim, the paper first? .

Thanks, I will read the paper and then kick off by asking some questions.
I am at home now, but doing some work as I have a deadline to meet.
I will be ready to start later tonight or tomorrow.

 

[Perpetual Student]

PS, for a relatively brief, non-technical overview, I recommend "In Search of Dark Matter", by Ken Freeman and Geoff McNamara (2006, Springer/Praxis; ISBN: 0-387-27616-5). Freeman, who must be close to retirement by now, is a professional astronomer who has been working on DM for just about his whole (professional) life, developed at least one of the observational tools used to test various DM hypotheses (i.e. PNe in the outskirts of galaxies), and has authored several hundred papers (not all as sole, or even lead, author of course!). There are other, popular-level, books on the topic, but this is the best that I've read.

Thanks for that. While I do find that MM's objections to standard cosmology far fetched, he does occasionally make some good points. When I see statements like:

Current interpretations of astronomical observations indicate that the age of the Universe is 13.73 (± 0.12) billion years,[1] and that the diameter of the observable Universe is at least 93 billion light years, or 8.80 × 1026 metres.

FROM: link

followed by the discovery that we have this magnitude of error LINK in our observations, I become quite perplexed. There appears to be quite a bit of hubris in a number like 13.75 +/- .12 years. If we do not have an accurate reading of "small stars" to the degree of a four-fold error, how can we come by such an exact estimate for the age of the universe.

 

[Monketi Ghost]

*snip*
Isn't science wonderful?

Yes! Especially when it's actual science!

 

[DeiRenDopa]

Thanks for that. While I do find that MM's objections to standard cosmology far fetched, he does occasionally make some good points. When I see statements like:


FROM: link

followed by the discovery that we have this magnitude of error LINK in our observations, I become quite perplexed. There appears to be quite a bit of hubris in a number like 13.75 +/- .12 years. If we do not have an accurate reading of "small stars" to the degree of a four-fold error, how can we come by such an exact estimate for the age of the universe.

I'm not sure I follow PS; the estimated age of the universe owes essentially nothing to what's in the paper that PR you provide a link to is based on (see my earlier posts) ... perhaps it would be of interest to you if I outlined how the age of the observable universe is estimated?

Or did you have some other question?