Mature stars in ancient galaxies

[SpaceTiger]

Thank you SpaceTiger for your comments, I will answer them carefully.Because turbo-1 had a point, and galaxies with mature stars at z = 6, that could have formed at z = 13.5, may prove to be those "hard to explain in lambda-CDM".

I will reiterate:

...even if the entire galaxy collapsed at z = 13.5, you still haven't shown that it's inconsistent with the standard model, nor have you cited any references that suggest a theoretical inconsistency.

You can't just wave your hands and say that it seems like it wouldn't work. You have to actually show it.

Baryonic DM resolves the galactic rotation curves, binds galactic clusters and lenses distant quasars. In order to resolve the problems with large-scale structure you need "non-pressurized" non-baryonic DM with properties chosen heuristically to make it fit. It is this hypothesis that I will question until DM is discovered in a laboratory.

Baryonic dark matter is ruled out by the MACHO results (a paper I'll probably link in my "Classic papers" post) and nucleosynthesis. The "non-pressurized" aspect follows directly from the need to be weakly-interacting (so as not to produce much light) and is not derived originally from LSS data. The only thing that was derived from LSS data was the "cold" part. We find that the universe looks entirely wrong if we assume the dark matter to be hot.

That has not yet happened and not for want of trying!

I hope you do understand that the very thing that makes it dark is that which makes it hard to detect.

I have, you will find a good resource of downloadable movies here. Notice that in the second and fifth movies that at z = 13.5 not much has happened.

The halos collapsing at z=13.5 would likely be very small and this simulation may not have the resolution to see them. It is standard CDM lore that reionization may have been caused by star formation at z ~ 17, so I don't think there are any theoretical problems there.

As you will have seen from my several posts on the subject the timescale in the standard Einstein-de Sitter model is too short for structure to form, even with non-baryonic DM. The hypothetical DE provides not only the acceleration necessary to fit the distant SN Ia data but also to stretch out these early time scales.

It does change the ages, but you certainly haven't shown that its required for the growth of structure. CDM theorists were having no trouble explaining LSS prior to 1998.

That depends on the physical properties of DE: quintessence? leaky branes? cosmological constant? etc. etc.? These properties have been heuristically chosen to make the model fit.

It sounds to me like you're just saying that the models are being consistent with the observations. God forbid! The simple fact that the universe is accelerating now implies a negative equation of state, which itself implies that dark energy was negligible at early times. What I'm saying is that you'd have to add extra parameters to your model (that changed the equation of state dramatically with time) to make it a contributor at nucelosynthesis.

The theory may be found for free on the physics ArXiv as well. It does fit cosmological constraints without invoking DE or exotic DM.

Given how little understanding of cosmology you've displayed in this thread, I find it hard to believe that your model correctly fits the data, and given how often you post links to your paper, I'm becoming increasingly convinced that you're a crank. If you're so sure that your theory is right, I suggest you try to hawk it in academic circles, where there are more people who can make a real critique.

I agree, but why choose an unknown exotic form of DM when ordinary baryonic matter (now mainly in the form of IMBH's?) may do the job just as well?

The primordial black hole solution is one possible explanation, but a large fraction of parameter space has already been ruled. Also, it's hard to form that many black holes in the early universe.

 

[SpaceTiger]

Obviously, not ANY guesses! I've been down that road...

Ok, how about we say, "guesses that aren't inconsistent with other observations"?

 

[Garth]

I will reiterate:
...even if the entire galaxy collapsed at z = 13.5, you still haven't shown that it's inconsistent with the standard model, nor have you cited any references that suggest a theoretical inconsistency.
You can't just wave your hands and say that it seems like it wouldn't work. You have to actually show it.

We have been discussing a paper about the observation of mature stars in galaxies of mass 1.3-3.8x10¹⁰M_solar at around z = 6, which may have formed as early as z = 13.5. As there seems to be a problem getting stars in dwarf galaxies to form beyond z = 7 because of re-ionization issues; see Formation of Dwarf Galaxies during the Cosmic Reionization, is not the onus is on the standard model to show that it is consistent with the observation of such galaxies and their stars?

Baryonic dark matter is ruled out by the MACHO results (a paper I'll probably link in my "Classic papers" post) and nucleosynthesis. The "non-pressurized" aspect follows directly from the need to be weakly-interacting (so as not to produce much light) and is not derived originally from LSS data. The only thing that was derived from LSS data was the "cold" part. We find that the universe looks entirely wrong if we assume the dark matter to be hot.

'Weakly-interacting' is a sufficent but not necessary condition for 'dark'. Interacting forms of matter can form dark objects, Jupiters or bricks for example - or my favourite IMBH's.

I hope you do understand that the very thing that makes it dark is that which makes it hard to detect.

Not necessarily; put an astronomically dark object into a laboratory - a comet nucleus of 5% albedo for example and it becomes very easy to detect!

The halos collapsing at z=13.5 would likely be very small and this simulation may not have the resolution to see them. It is standard CDM lore that reionization may have been caused by star formation at z ~ 17, so I don't think there are any theoretical problems there.

It uses 1000,000,000 particles! Masses of 10⁶M_solar form at z ~ 17, we are talking about ~10¹⁰M_solar.

It does change the ages, but you certainly haven't shown that its required for the growth of structure. CDM theorists were having no trouble explaining LSS prior to 1998.

Structure takes time.

It sounds to me like you're just saying that the models are being consistent with the observations. God forbid! The simple fact that the universe is accelerating now implies a negative equation of state, which itself implies that dark energy was negligible at early times. What I'm saying is that you'd have to add extra parameters to your model (that changed the equation of state dramatically with time) to make it a contributor at nucelosynthesis.

So we know what DE is do we, and therefore know its equation of state? Or do we simply know what equation of state we require and therefore what kind of DE we have to invoke to make the model concordant?

Given how little understanding of cosmology you've displayed in this thread, I find it hard to believe that your model correctly fits the data, and given how often you post links to your paper, I'm becoming increasingly convinced that you're a crank. If you're so sure that your theory is right, I suggest you try to hawk it in academic circles, where there are more people who can make a real critique.

Forgive me for promoting my theory, but when you say: "There aren't yet any competing theories that can say the same." and there clearly is at least one I feel bound to contradict you. Perhaps I am a crank, (actually I prefer the term 'maverick'!), on the other hand cranks are not published in GRG, and the theory is discussed in academic circles with now 49 other author citations in peer reviewed journals. Its main plus point is that it is falsifiable and being tested at the moment as the Gravity Probe B experiment comes to its conclusion.

The primordial black hole solution is one possible explanation, but a large fraction of parameter space has already been ruled. Also, it's hard to form that many black holes in the early universe.

Agreed - a task in hand!

Garth

 

[turbo]

Ok, how about we say, "guesses that aren't inconsistent with other observations"?

If you are willing to consider that "empty" space is a transmissive medium and that the field of the quantum vacuum can exhibit densification and polarization like any other field, I can deliver "guesses" that are not only not consistent with observation, but make sense of some very perplexing problems.

If we insist that the quantum vacuum is exactly equivalent to "empty" space and that all EM of all wavelengths propagates through it with NO interaction, we will never manage to come up with a cosmological model that can allow the reconciliation of gravity with the three fundamental forces. The BB theory is founded on this "no interaction" concept. You may be interested in knowing that Edwin Hubble was not comfortable with this concept, or the "cosmological expansion" that was posited based on his observations.

I am in my mid-50s, and am trying to build a retirement fund, so I don't have the time or resources to go back to school and provide mathematical quantification for this model. You'll be able to dismiss me as a crank at for at least the next 10-12 years - tons of fun! I am an amateur astronomer and an ABO -certified optician, and initially started studying the quantum vacuum in order to explore a classical optical model for "gravitational" lensing that does not rely on the concept that massless photons follow geodesics in curved space-time.

 

[SpaceTiger]

We have been discussing a paper about the observation of mature stars in galaxies of mass 1.3-3.8x10¹⁰M_solar at around z = 6, which may have formed as early as z = 13.5. As there seems to be a problem getting stars in dwarf galaxies to form beyond z = 7 because of re-ionization issues; see Formation of Dwarf Galaxies during the Cosmic Reionization

It's suggesting that a z = 7 reionization yields a UV background that suppresses star formation at z < 7, which is exactly the opposite of what you're trying to show...

Also, the first two sentences of the paper:

In the context of cold dark matter (CDM) cosmology,
the first generation of objects should have the mass of
∼ 106M⊙ and form at redshifts of 20 . z . 50 (Tegmark
et al. 1997; Fuller & Couchman 2000). At later epochs, the
first objects are assembled into larger systems in a hierarchical
fashion to form dwarf or normal galaxies.

...which is of course exactly what I was saying earlier in the argument. Combine the above with the fact that the observations are selectively finding the brightest objects and thus sampling the high-mass tail of the galaxy distribution and I would say that the standard model is pretty safe.

'Weakly-interacting' is a sufficent but not necessary condition for 'dark'. Interacting forms of matter can form dark objects, Jupiters or bricks for example - or my favourite IMBH's.

I was assuming a particle source of dark matter (which seems much more probable given the observations), but I can assure you that "bricks" would not be pressurized either.

Not necessarily; put an astronomically dark object into a laboratory - a comet nucleus of 5% albedo for example and it becomes very easy to detect! It uses 1000,000,000 particles!

That requires you to actually find it first! If you concentrate the dark matter into massive objects, then they also become very sparse and the chances of one passing close enought to detect becomes very small. If you're looking for another calculation to do, try calculating the number of dark matter objects that would pass through the solar system in a decade as a function of their mass given the current observational data.

Masses of 10⁶M_solar form at z ~ 17, we are talking about ~10¹⁰M_solar.

Again, I'm going to refer you to the hierarchical model of growth. All of the stars in the galaxy do not have to be formed at the time of the galaxy itself. The observational limits are on the ages of the stars.

So we know what DE is do we, and therefore know its equation of state? Or do we simply know what equation of state we require and therefore what kind of DE we have to invoke to make the model concordant?

We were talking in the context of dark energy models, so I naturally assumed that we would be discussing ones that fit the data.

Forgive me for promoting my theory, but when you say: "There aren't yet any competing theories that can say the same." and there clearly is at least one I feel bound to contradict you.

What I actually said was:

I don't disagree that dark matter and dark energy are unsettling, but they fit the data and have even made successful predictions. There aren't yet any competing theories that can say the same.

I'll grant you the possibility that your theory fits the data (though I doubt it), but what successful predictions have you made?

Perhaps I am a crank, (actually I prefer the term 'maverick'!), on the other hand cranks are not published in GRG

Actually, I'll bet they do

and the theory is discussed in academic circles with now 49 other author citations in peer reviewed journals. Its main plus point is that it is falsifiable and being tested at the moment as the Gravity Probe B experiment comes to its conclusion.

I look forward to the results.

 

[Chronos]

Unsurprisingly enough, I agree with ST. The arguments in favor of some amount of CDM [and very likely a huge fraction] are overwhelming. Virtually every other model that relies on black holes, MACHO's, or other baryonic entities has been [in my opinion] been convincingly ruled out. And these are not 'educated guesses', they are supported by cold, hard statistical probabilities that bombard us from many different directions. I don't like injecting unobserved entities into the big picture, but liking it is optional. And betting against the odds on favorite rubs me wrong. I can't bring myself to write it all off as coincidence. On the other hand, I have a sneaking suspicion the truth is even weirder than we imagine. I lean toward the notion DM and DE are manifestations of the same underlying principle. I will even be so bold as to suggest they are the missing entities in the correct theory of quantum gravity.

 

[SpaceTiger]

I am in my mid-50s, and am trying to build a retirement fund, so I don't have the time or resources to go back to school and provide mathematical quantification for this model. You'll be able to dismiss me as a crank at for at least the next 10-12 years - tons of fun! I am an amateur astronomer and an ABO -certified optician, and initially started studying the quantum vacuum in order to explore a classical optical model for "gravitational" lensing that does not rely on the concept that massless photons follow geodesics in curved space-time.

Look, turbo, you're a nice guy, probably much nicer than I, but you must have some idea for why I find your theoretical "contributions" inappropriate. It's not just that you can't do math, it's also that you really aren't that knowledgeable about modern astronomy, at least relative to the professionals. We devote our lives to studying these things, so you shouldn't be ashamed of this fact, but you should certainly consider it before trying tell an entire community of scientists that they're misguided. Humility is the key word here. If I were to burst into somebody's office, having no training in their area of expertise, and proceed to tell them that they were doing everything wrong, don't you think that person would have a right to be upset?

Physical science, as performed by the community in which I and others work, demands a certain level of rigor and responsibility if it is to be carried out effectively. Insomuch as this forum is considered to be one in which real science is discussed, I don't think its unreasonable of me to demand that same level of rigor and responsibility from you. The fact that you have no quantitative backing for your theory renders it, in my view, inviable to even make predictions.

 

[Garth]

It's suggesting that a z = 7 reionization yields a UV background that suppresses star formation at z < 7, which is exactly the opposite of what you're trying to show...

Actually what the original paper says is galaxies with stars that formed prior to z ~ 7 have been observed. I'm not trying to show anything except there may be a problem reconciling observation with the standard theory, but you well be right to say "the standard model is pretty safe".

I was assuming a particle source of dark matter (which seems much more probable given the observations), but I can assure you that "bricks" would not be pressurized either.

They would be, before they became "bricks - or whatever".

That requires you to actually find it first! If you concentrate the dark matter into massive objects, then they also become very sparse and the chances of one passing close enought to detect becomes very small. If you're looking for another calculation to do, try calculating the number of dark matter objects that would pass through the solar system in a decade as a function of their mass given the current observational data.

My suggestion is that DM is originally baryonic and now found mainly in intermediate mass BH's (10² - 10⁴ that are the end state of massive PopIII stars in the supposed range (10² - 10⁵) M_Solar.

So taking 10³ M_Solar as a 'typical' value. For rich cluster DM it would take 10¹² of 10³ M_Solar BHs. Typical rich cluster size? 10⁷ parsecs diameter? Volume ~10²¹ parsecs³ , IMBH density ~ one per ~10⁹ parsecs³, i.e. ~ one per 10³ parsecs in ball park numbers.

Is it unreasonable to suggest there is an IMBH every thousand parsecs?

I'll grant you the possibility that your theory fits the data (though I doubt it), but what successful predictions have you made?

That the Pioneer spacecraft should appear to suffer a sunwards acceleration equal to cH, that the Earth should appear to 'spin-up' relative to the orbital period of the moon by H - both of which may already have been observed.

Actually, I'll bet they do

Try telling that to the GRG editorial board, they are pretty sharp - and how!

I look forward to the results.

Likewise - and how!
Garth

 

[SpaceTiger]

Actually what the original paper says is galaxies with stars that formed prior to z ~ 7 have been observed.

That would be z > 7, an epoch in which the paper says it's easier to form stars.

They would be, before they became "bricks - or whatever".

They can't have become "bricks" after nucleosynthesis because we have tight constraints on the relative density of baryons at that time, so that would be irrelevant for the growth of structure. The only viable "bricks" at this point seem to be PBHs, and those would be pressureless as well.

Is it unreasonable to suggest there is an IMBH every thousand parsecs?

That depends on who you ask, but I'll admit it's a possibility (though only for primordial black holes).

That the Pioneer spacecraft should appear to suffer a sunwards acceleration equal to cH, that the Earth should appear to 'spin-up' relative to the orbital period of the moon by H - both of which may already have been observed.

If you predicted the magnitude of the acceleration of Pioneer, it would give me pause, but otherwise, I would say that's not very impressive. Same with the spin-up of the earth. The standard model (including DM and DE), on the other hand, predicted the shape of the CMB power spectrum to very high precision.

 

[Garth]

If you predicted the magnitude of the acceleration of Pioneer, it would give me pause, but otherwise, I would say that's not very impressive. Same with the spin-up of the earth. The standard model (including DM and DE), on the other hand, predicted the shape of the CMB power spectrum to very high precision.

You'll find it all discussed in my latest published paper, arXived here. A Concordant “Freely Coasting” Cosmology produced by SCC also gives "the location of the primary acoustic peaks in the same range of angles as that given in Standard Cosmology."

Garth

 

[SpaceTiger]

...gives "the location of the primary acoustic peaks in the same range of angles as that given in Standard Cosmology."

I took a look at the paper you cited for that (Gehaut et al. 2003). First of all, as far as I can tell, this paper was never accepted for publication (please send me a link if this is incorrect). Second of all, they don't claim to show precise concordance with the CMB (as with the standard model), they instead say:

Essential features of CMB anisotropy follow from the above analysis. In
the rest of this article we shall be content with making rough estimates
of CMB anisotropy peak locations to judge whether there is any a-priori
discordance with observations.

I'm not even convinced that the above is correct. In equation 58, they give an expression for a forced and damped harmonic oscillator that's supposed to describe the acoustic fluctuations. Fine, I'll accept that, but this equation alone isn't enough to reproduce the acoustic peaks. One also needs the appropriate initial conditions; that is, the modes must be synchronized by some process. In the standard model, inflation is responsible for this, but you say you don't invoke inflation in your model. How do the modes synchronize?

 

[Garth]

If you predicted the magnitude of the acceleration of Pioneer, it would give me pause

It does -almost, the anomalous acceleration a_P = (8.74±1.33)×10⁻⁸ cm/s² is close to the value of 'Hubble acceleration' H_a = cH = 6.69×10⁻⁸cm/s².
This may be explained by a 'clock slip' between ephemeris time and atomic time. Relativity Theory and a Real Pioneer Effect , by Peter Ostermann

Keeping the relativistic laws of motion a non-conventional Pioneer effect would prove an increase of the scale rate of atomic clocks in comparison with planetary ones.

The discrepancy between the observed effect and cH may be easily explained by residual radiation anisotropy and gas leakage by the spacecraft . Such a clock slip is predicted by SCC.

I took a look at the paper you cited for that (Gehaut et al. 2003). First of all, as far as I can tell, this paper was never accepted for publication (please send me a link if this is incorrect).

The Indian team's work on freely coasting cosmology has only been published on the arXiv; Kolb's original paper "A Coasting Cosmolgy" was published Ap.J. 344.543-550 1989 Sept. 15.

Second of all, they don't claim to show precise concordance with the CMB (as with the standard model), they instead say:

Essential features of CMB anisotropy follow from the above analysis. In the rest of this article we shall be content with making rough estimates of CMB anisotropy peak locations to judge whether there is any a-priori discordance with observations.

I'm not even convinced that the above is correct. In equation 58, they give an expression for a forced and damped harmonic oscillator that's supposed to describe the acoustic fluctuations. Fine, I'll accept that, but this equation alone isn't enough to reproduce the acoustic peaks. One also needs the appropriate initial conditions; that is, the modes must be synchronized by some process. In the standard model, inflation is responsible for this, but you say you don't invoke inflation in your model. How do the modes synchronize?

There is still work to do – resources have not been as forthcoming as for the standard model! The freely coasting CMB temperature anisotropy power spectrum has to be fine tuned by the initial conditions, no more so, however, than the standard model, with its many parameters. The Gehlaut paper finishes by saying:

Finally, we are tempted to mention that a linear coasting cosmology presents itself as a falsifiable model. It is encouraging to observe its concordance ! In standard cosmology, falsifiability has taken on a backstage - one just constrains the values of cosmological parameters subjecting the data to Bayesian statistics. Ideally, one would have been very content with a cosmology based on physics that we have already tested in the laboratory. Clearly, standard cosmology does not pass that test. One needs a mixture of hot and cold dark matter, together with (now) some form of dark energy to act as a cosmological constant, to find any concordance with observations. In other words, one uses observations to parametrize theory in Standard Cosmology.
Linear coasting presents a very distinguishable cosmology. Recombination occurs at age ~ 10⁷ years as opposed to ~10⁵ years in standard cosmology. The Hubble scale at decoupling is thus two orders of magnitude greater in linear coasting. This fact, coupled with the absence of any horizon, could well have falsified linear coasting. Any concordance with observations is therefore very significant. The model comes with its characteristic predictions.
Thus linear coasting has the potential of relegating the need for any form of dark matter or dark energy (or for that matter, any physics not already tested in the laboratory) to the physics archives where they enjoy the same status as ether and phlogiston. The message this article is to convey is that a universe that is born and evolves as a curvature dominated model has a tremendous concordance and there are sufficient grounds to explore models that support such a coasting.

SCC does support such a coasting and it is being independently tested at this moment; to be falsified or otherwise; we wait and see.

Garth

 

[Phobos]

This discussion is fascinating to watch, but I feel I need to step in here. I think SpaceTiger has explained the mainstream model's response to the OP. Garth is bringing the discussion into SCC, for which we have other dedicated threads. And turbo-1 is touching upon an alternative theory (for which I look forward to seeing in the Independent Research forum). Plus, some of the comments are getting a bit more personal. So, I'm closing this one up. But if you 3 really would like to keep hashing it out here, let me know via PM. You also have the option of continuing 1-on-1 via PMs. Thanks.