# Quasar anomalies

Science Advisor
Gold Member
I am very disturbed by the lack of time dilation in the variability of quasar v redshift studies.

http://www.arxiv.org/abs/astro-ph/0105073
Title: Time Dilation and Quasar Variability
Authors: M.R.S. Hawkins
The timescale of quasar variability is widely expected to show the effects of time dilation. In this paper we analyse the Fourier power spectra of a large sample of quasar light curves to look for such an effect. We find that the timescale of quasar variation does not increase with redshift as required by time dilation. Possible explanations of this result all conflict with widely held consensus in the scientific community.

I think this is a very serious challenge to modern theory.

Last edited:

## Answers and Replies

Garth
Science Advisor
Gold Member
All quiet on the Western Front!

It is indeed a disturbing paper, thank you Chronos, Fred Hoyle would have loved it!
The explanations for the lack of a time dilation effect in quasar light curves, all of which conflict with broad consensus in the astronomical community.

Firstly, time dilation might not in fact be a property of the Universe, which would effectively mean that the Universe was not expanding. Apart from the overwhelming support for the big bang theory, the direct measurements of time dilation quoted above strongly argue against this.

The second possibilty is that quasars are not at cosmological distances. This is an argument which was hotly disputed in the 1970s, with an emerging consensus favouring cosmological distances. This has subsequently been strongly confirmed by studies of quasar host galaxies at high redshift.

The third possibility is that the observed variations are not intrinsic to the quasars but caused by some intervening process at lower redshift, such as gravitational microlensing. Although this idea has been strongly argued (Hawkins 1996), there is an opposing view that variations in quasars are dominated by instabilities in the central accretion disc. The reality of this mode of variability in active galactic nuclei is supported by detailed observations of Seyfert galaxies (Peterson et al. 1999) and gravitationally lensed quasars (Kundi´c et al. 1997), where the presence of intrinsic variations cannot be in doubt. The debate centres on whether this mechanism is responsible for the long timescale large amplitude variations which dominate the power spectra discussed in this paper.
Reactions?

Garth

Science Advisor
Gold Member
The the lensing explanation is a nice try:

http://www.arxiv.org/abs/astro-ph/0306434
Title: Can Microlensing Explain the Long-Term Optical Variability of Quasars?
Authors: Erik Zackrisson, Nils Bergvall, Thomas Marquart, Phillip Helbig
. . . Although controversial, the scenario of microlensing as the dominant mechanism for the long-term optical variability of quasars does provide a natural explanation for both the statistical symmetry, achromaticity and lack of cosmological time dilation in quasar light curves.

Unfortunately, it does not appear to hold water:

Structure Function Analysis of Long Term Quasar Variability
http://www.arxiv.org/abs/astro-ph/0411348
Authors: W. H. de Vries (1,2), R. H. Becker (1,2), R. L. White (3), C. Loomis
. . . We find the following: (1) the outbursts have an asymmetric light-curve profile, with a fast-rise, slow-decline shape; this argues against a scenario in which micro-lensing events along the line-of-sight to the quasars are dominating the long-term variations in quasars.

The authors understate the case in asserting this study 'argues against' microlensing. There is overwhelming evidence quasars are not local [i.e., within this galaxy], but, this is a serious blow to 'cosmology as usual', IMO. P.S, I'm not ready to buy any 'tired light' stock.

I searched long and hard trying to find a fatal flaw, or sensible explanation to the issue raised; and came up empty. What I find shocking is how little attention this has been given in the literature. I'm experiencing that same feeling I had as a child when mom, after intense grilling, admitted there was no Santa Claus.

Last edited:
Nereid
Staff Emeritus
Science Advisor
Gold Member
well worth studying further!

Some suggestions:
• Hawkins' analysis. It's highly unlikely that it contains gross errors (it wouldn't have passed peer-review), but maybe there are some subtle ones?
• An alternative analysis of the data. He employed one particular approach to determining a 'time dilation' footprint in the data - perhaps the same data, analysed a different way, might give a different result?
• Selection effects. This is the bane of astronomers' life, and some of these effects are subtle indeed. Perhaps a cold, hard look at the inputs - as compared with what we now know about quasars, and what we know we don't know - might turn up patterns that weaken the stated conclusion? For example:
• a) redshift-apparent magnitude. In the standard view, the higher the redshift, the greater the distance. Among other things this also means that two quasars with different redshifts but the same apparent magnitude will have quite different absolute magnitudes. In a (apparent) magnitude-limited selection (that was Hawkins' input catalogue, yes?), this introduces biases in the sample.
• b) colour. The input catalogue wasn't (AFAICS) characterised for quasar colour; there could be all kinds of selection effects relating to quasar colour (more later, if I have time).
• c) Variability. The quasars to be studied were not selected because of their (then known) variability. However, the extent to which the variability (or lack of it) played a part in them being detected as quasars in the first place should definitely be looked into.
• The nature of quasars. Unlike Cepheids or SNe, the details of quasars' variability is essentially unknown ('accretion disks' might be responsible for most of such variability, but just how do they give rise to the observed frequency spectrum?) Without some handle on this, the intrinsic causes and nature of quasar variability, I don't see how alternative explanations for an apparent absence of time dilation could be ruled out - intrinsically brighter quasars are variable in ways that are different from those not so bright? evolution effects? observed variability is due to the integration of several, quasi-independent causes?
I don't see much chance of a resolution via theory any time soon (there's just too much work to do, involving a lot of heavy-duty physics), so maybe an observational project could yield results (confirmation, or not) in the short term?

For example, studies of the observed variability of quasars, in several time regimes, in spectra, in different wavebands (gamma, X-ray, UV, NIR, FIR, ...), ... to tease out any systematic effects and put constraints on them.

Last edited:
wolram
Gold Member
http://arxiv.org/abs/astro-ph/0106220

Fourier Analysis of Gamma-Ray Burst Light Curves: Searching for Direct Signature of Cosmological Time Dilation
Authors: Heon-Young Chang (Korea Institute For Advanced Study)
Comments: 12 pages, 2 figures, 2 tables, accepted to ApJL

We study the power density spectrum (PDS) of light curves of the observed gamma-ray bursts (GRBs) to search for a direct signature for cosmological time dilation in the PDS statistics with the GRBs whose redshifts $z$'s are known. The anticorrelation of a timescale measure and a brightness measure is indirect evidence of its effect. On the other hand, we directly demonstrate that a time dilation effect can be seen in GRB light curves. We find that timescales tend to be shorter in bursts with small redshift, as expected from cosmological time-dilation effects, and we also find that there may be non-cosmological effects constituting to this correlation. We discuss its implication on interpretations of the PDS analysis results. We put forward another caution to this kind of analysis when we statistically exercise with GRBs whose $z$ is unknown.
An older paper.

SpaceTiger
Staff Emeritus
Science Advisor
Gold Member
Nereid said:
It's highly unlikely that it contains gross errors (it wouldn't have passed peer-review)
I wouldn't give the peer review process that much credit. My roommate recently reviewed a paper that was absolutely loaded with errors and poor reasoning -- and it was nearly identical to several that had already been published. Unfortunately, many peer reviewers are just lazy.

That said, Hawkins doesn't appear to be a crackpot, so I wouldn't dismiss the paper outright. It will be interesting to see how this is resolved.

Garth
Science Advisor
Gold Member
SpaceTiger said:
That said, Hawkins doesn't appear to be a crackpot, so I wouldn't dismiss the paper outright. It will be interesting to see how this is resolved.
Mike Hawkins is a doctorate member of staff of the Royal Observatory, Edinburgh and certainly not a 'crackpot'.

I agree with Chronos
What I find shocking is how little attention this has been given in the literature.
The most disturbing thing about this paper is the lack of interest. I would have thought that it would have stirred up a hornet's nest, either of refutations or a major effort of reconciliation with the standard model. After four years there has been more of less nothing published. The 'silent treatment' perhaps?

Those were very good points Nereid, especially the question of selection and colour dependent variability effects. From that OP paper of Hawkins:
The quasars in the field were found by a variety of techniques, including ultra-violet excess,variability, blue drop-out and objective prism. Altogether some 600 quasars have now been identified, with confirming redshifts in the range 0.1 < z < 3.5. There are sufficient numbers that the quasars can be binned in both redshift and luminosity to avoid the well-known degeneracy between these two parameters. All the quasars used in this study fluctuated significantly in brightness over the 24 year monitoring period, with an amplitude of mode 0.6 mag and a tail extending to 2 mag. In order to compare the spectrum of variations of subsamples of quasars from the survey, a Fourier power spectrum was calculated for each light curve. The quasars were then binned in red-shift and luminosity, in such a way that each bin contained approximately 100 objects, with a total of 407 quasars used for the analysis.
Quite a statistically significant sample?

We note the raw details of observed cosmological time dilation so far: Time dilation is seen in distant S/N decay profiles, in slow GRBs but not (apparently) in quasar variability. Could it be (if slow GRBs are distant hyper-novae) that in the first two the engine is basically 'normal' matter undergoing nuclear conflagration, whereas with a quasar the engine is degenerate mass, i.e. a black hole?

In http://en.wikipedia.org/wiki/Self_creation_cosmology [Broken] non-degenerate matter and degenerate matter behave differently, because the scalar field is coupled to non-degenerate matter but decoupled from relativistic matter, therefore cosmological time dilation is to be expected in distant S/Ns but not BHs. I just thought I'll add that as a suggestion!

Garth

Last edited by a moderator:
Nereid
Staff Emeritus
Science Advisor
Gold Member
Thinking about this some more, I see less reason to be concerned at the apparent absence of a time dilation signal in the data.

First and foremost, in the mainstream view of quasars, we have quasar evolution - http://arxiv.org/abs/astro-ph/0005368" [Broken], perhaps. If high-z quasars are different from low-z ones, then, a priori, expecting their (rest frame) variability to be unchanged is rather foolish, isn't it?

It may be possible to take some different views though Hawkins' data (as "a Fourier power spectrum was calculated for each [quasar's] light curve"), to look for an evolutionary effect, but the data as presented in the paper is too coarsely binned to do such a study.

Another way to test this may be to look at the power spectra of local AGNs (Seyfert nuclei, BL Lacs, ...).

Second, slicing and dicing the dataset in other ways would have been helpful - in terms of how the quasars were detected, for example, or weighted for 'completeness' (by comparison with data from SDSS, say), or X-ray or radio brightness.

Third, some 'field controls' would have increased confidence in the outputs (e.g. power spectra of variable stars on the plates) - I wonder why this wasn't done?

Fourth, why not make some artificial quasars? Modelling (monochromatic) variability, in a computer, should be a piece of cake - the outputs from the artificial quasars, as discrete 'plate magnitudes' (complete with errors and 'cloudy nights'), could then be fed into Hawkins' analysis pipeline. By tweaking the 'quasar properties' (evolutionary history - luminosity, variability, colour, ...), it should be fairly straight-forward to find out what sorts of things could mimic Hawkins' ~600 power spectra.

Finally, I think a different kind of analysis (approach) would be welcome.

Last edited by a moderator:
Science Advisor
Gold Member
My impression was Hawkins bent over backwards trying to find a way to explain this unexpected result. His publication history suggests he is not afraid to go out on a limb, but they tend to be thick.

Nereid, my objection to relying upon quasar evolution is the extraordinary fine tuning it appears to require. The coarse binning actually strengthens the result, IMO. This smoothes out the oft seen outrageous probabilities suggested by over-binning [a typical crackpot tactic]. It is also evident there are two broad color classes of quasers. Assuming different mechanisms are involved, it appears improbable both would seemlessly cancel out the expected time dilation effect [please don't sentence me to TD ]

I don't entirely get the variable star thing. I suppose that would be a way of testing for selection effects, but given the large data set, I doubt any systematic effects of that nature are in play.

I like the computer modelling suggestion, Nereid. Sounds like good thesis material. This is surely something that demands further study.

I am also concerned about how this same logic could be applied to the apparent time dilation of supernova and GRB light curves. This inconsistency is what I find most troubling.

Nonetheless, Nereid, your observations are soundly based and logically consistent. And that is exactly what I expected to find from the cosmology community. But, their silence is deafening.

Last edited:
Garth
Science Advisor
Gold Member
Chronos said:
Nonetheless, Nereid, your observations are soundly based and logically consistent. And that is exactly what I expected to find from the cosmology community. But, their silence is deafening.
Absolutely, Nereid your ideas appear to be worthy of a good hearing, if nobody else has done so, why not write a paper?

Garth

Nereid
Staff Emeritus
Science Advisor
Gold Member
Chronos said:
My impression was Hawkins bent over backwards trying to find a way to explain this unexpected result. His publication history suggests he is not afraid to go out on a limb, but they tend to be thick.
All the more curious then that he seems not to have done several of the (to me) more obvious 'sanity checks' (or, if you prefer, quality controls).
Nereid, my objection to relying upon quasar evolution is the extraordinary fine tuning it appears to require.
I think the operative word is "appears" - without doing some simulation, I don't see how anyone could say just how 'extraordinary' any 'fine tuning' would need to be (more later, not necessarily in this post).
The coarse binning actually strengthens the result, IMO. This smoothes out the oft seen outrageous probabilities suggested by over-binning [a typical crackpot tactic]. It is also evident there are two broad color classes of quasers. Assuming different mechanisms are involved, it appears improbable both would seemlessly cancel out the expected time dilation effect [please don't sentence me to TD ]
Not at all - we tend to get tunnel vision, when it comes to 'colour'. 'Red' and 'blue' actually differ very little, when the full range of EM that quasars are well known to emit over, in significant quantities, is considered.
I don't entirely get the variable star thing. I suppose that would be a way of testing for selection effects, but given the large data set, I doubt any systematic effects of that nature are in play.
You could think about it as just a 'being careful' step, or you could say that without this, the conclusions rest on weak foundations.

Imagine there are ~600 variables in the same field(s) where the quasars are to be found. Imagine their colour and (apparent) magnitude distributions are similar to those of the quasars. Imagine Hawkins produced 600 Fourier power spectra, of these variables. Imagine that a computer program blindly, and randomly, applied 'time dilation' to subsets of those spectra, in a distribution which matched the z's of the quasars.

Now feed those two sets of 600 power spectra into Hawkins' "bin and analyse" pipeline ... what would the results be?

At the very least, we would have (hopefully) internal consistency checks on the approach (and tools) which Hawkins used.
I like the computer modelling suggestion, Nereid. Sounds like good thesis material. This is surely something that demands further study.
How about we lay the groundwork, here in PF? (more later).
I am also concerned about how this same logic could be applied to the apparent time dilation of supernova and GRB light curves. This inconsistency is what I find most troubling.
Different bathtub of fish ... quasars are a zoo, of animals which range from shrews to elephants; SNe and GRBs are private collection of different species of mice.

Nereid
Staff Emeritus
Science Advisor
Gold Member
Just quickly - another systematic effect might be evident in the fainter (apparent mag) quasars.

The errors in estimating magnitude would have been - presumably - greater for fainter images; to what extent was this incorporated in the analysis? The paper seems to say estimates of magnitude were all given the same (per plate?) errors.

Also, for quasars near the (faint) limit, how many 'disappeared' over the history of the data collection (i.e. dimmed below detectability)? If the mode was 0.6 mag, "with a tail extending to 2 mag", this is not a trivial consideration.

Dare one ask why anyone hasn't repeated the observations - to at least prove them wrong?

Nereid
Staff Emeritus
Science Advisor
Gold Member
ratfink said:
Dare one ask why anyone hasn't repeated the observations - to at least prove them wrong?
Welcome to Physics Forums, ratfink!

From the Hawkins paper:
a large sample of quasars which have been homogeneously monitored every year for 24 years
IOW, it isn't easy to 'repeat' them.

It is certainly worth checking various observatory (plate) records, to see what sort of comparable consistent, (historical) datasets there might be.

Any suggestions?

Thanks,
It is just that I read this quote

SpaceTiger said:
I wouldn't give the peer review process that much credit. My roommate recently reviewed a paper that was absolutely loaded with errors and poor reasoning -- and it was nearly identical to several that had already been published. Unfortunately, many peer reviewers are just lazy.

That said, Hawkins doesn't appear to be a crackpot, so I wouldn't dismiss the paper outright. It will be interesting to see how this is resolved.
So do the plates lie? If not, are they part of the public domain? If so, they could be checked to see if 'non time dilation' is what the results show and that it is not a 'mistake'. Would other scientists looking at the same data set come to the same conclusions - or different ones? and if so why haven't they done it?

SpaceTiger
Staff Emeritus
Science Advisor
Gold Member
ratfink said:
So do the plates lie? If not, are they part of the public domain? If so, they could be checked to see if 'non time dilation' is what the results show and that it is not a 'mistake'. Would other scientists looking at the same data set come to the same conclusions - or different ones? and if so why haven't they done it?
Different researchers have reached this same conclusion -- that there is no apparent time dilation in the quasar light curves. I don't think many people argue the results, it's mostly a question of interpretation. In my opinion, the most likely explanation is some kind of evolution (see Nereid's posts). I don't think it would take a great deal of fine-tuning to reproduce these results because the error bars are still large (the high- and low-redshift subsamples appear to only be a few sigma apart). If we reduce the size of the error bars by another factor of a few and still see no significant difference in the subsamples, then I think that would be cause for concern.

Keep in mind that the author, in the introduction to his paper, makes note of previous studies that had already confirmed the existence of cosmological time dilation in other sources (GRBs, SNe), so I suspect we're not seeing much interest in this topic because the mainstream has already dismissed this effect as evolution (or selection effects). Although this kind of evolution is interesting in of itself, it's considerably less boat-rocking than a challenge to mainstream cosmology.

Thanks,
But I thought that in science to 'prove' something then one had to look at the same sort of thing from all sorts of angles and show that it is consistent. If one has time dilation in SIa's but not in quasars then isn't 'confirm' the wrong word to use for time dilation?

SpaceTiger
Staff Emeritus
Science Advisor
Gold Member
ratfink said:
Thanks,
But I thought that in science to 'prove' something then one had to look at the same sort of thing from all sorts of angles and show that it is consistent. If one has time dilation in SIa's but not in quasars then isn't 'confirm' the wrong word to use for time dilation?
I'm not sure what you mean. Cosmological time dilation has been confirmed to exist in SNe and (possibly) GRBs, but not in quasars. Nothing has been proven 100%, but the effect has been observed in those objects to whatever significance the observations can be trusted. It's possible there is some exotic explanation for the effect (like Garth's theory), but I'm just talking about observations, not theory.

Thanks,
SpaceTiger said:
I'm not sure what you mean. Cosmological time dilation has been confirmed to exist in SNe and (possibly) GRBs, but not in quasars. Nothing has been proven 100%, but the effect has been observed in those objects to whatever significance the observations can be trusted. It's possible there is some exotic explanation for the effect (like Garth's theory), but I'm just talking about observations, not theory.
I was just wondering why supernova Ia results are said to be 'proof' and consequently quasar results must be 'flawed' as far as time dilation is concerned. Why not the other way around? i.e. Quasar 'non time dilation' show the Universe is not expanding and supernovae Ia results are an 'exotic effect?'
BTW http://xxx.lanl.gov/abs/astro-ph/0511628"

Last edited by a moderator:
selfAdjoint
Staff Emeritus
Gold Member
Dearly Missed
ratfink said:
Thanks,
But I thought that in science to 'prove' something then one had to look at the same sort of thing from all sorts of angles and show that it is consistent. If one has time dilation in SIa's but not in quasars then isn't 'confirm' the wrong word to use for time dilation?
Go back and read Nereid's post on this; if it's too compressed for you I'm sure she'd be glad to expand it. Then pay attention to Space Tiger's remarks about error bars. From just these two posts we find: (1)There is a plausible explanation for the plates, and (2)Astronomical data is inherently noisy. And so the case is still open. Time dilation is supported by a huge amount of independent evidence, and this contradictory evidence is perhaps not all it seems to be.

In science you never "prove" anything, you just have more or less support. I repeat, dilation has an enormous amount of supporting evidence.

selfAdjoint said:
Go back and read Nereid's post on this; if it's too compressed for you I'm sure she'd be glad to expand it. Then pay attention to Space Tiger's remarks about error bars. From just these two posts we find: (1)There is a plausible explanation for the plates, and (2)Astronomical data is inherently noisy. And so the case is still open. Time dilation is supported by a huge amount of independent evidence, and this contradictory evidence is perhaps not all it seems to be.

In science you never "prove" anything, you just have more or less support. I repeat, dilation has an enormous amount of supporting evidence.
All I am asking is why is 'time dilation' in supernovae taken as fact and 'non time dilation' in quasars put down to an 'exotic effect?'

Time dilation is supported by a huge amount of independent evidence
isn't it all SnIa's? (Gamma Ray bursts seem have a long way to go to support anything)

SpaceTiger
Staff Emeritus
Science Advisor
Gold Member
ratfink said:
All I am asking is why is 'time dilation' in supernovae taken as fact and 'non time dilation' in quasars put down to an 'exotic effect?'
The facts are:

- Supernovae exhibit time dilation
- GRBs exhibit time dilation (somewhat more tentatively)
- Quasars do not (to the current precision)

That's it. I don't know why you're trying to read into this so much. From the theoretical standpoint, I find it very hard to believe that the explanation for the apparent lack of time dilation in quasars is due to new physics and I've already explained why I think it's an evolutionary effect.

SpaceTiger said:
The facts are:

- Supernovae exhibit time dilation
- GRBs exhibit time dilation (somewhat more tentatively)
- Quasars do not (to the current precision)

That's it. I don't know why you're trying to read into this so much. From the theoretical standpoint, I find it very hard to believe that the explanation for the apparent lack of time dilation in quasars is due to new physics and I've already explained why I think it's an evolutionary effect.
Sorry to be pedantic here but this is incorrect.
The FACTS are that:
Light curves from supernovae are stretched.
Light curves from quasars are not stretched.
Now some people say that the stretching of supernovae Ia light curves is explained by 'time dilation' and that the non stretching of quasar light curves is an 'exotic effect!"
Others wonder why they cherry pick.

SpaceTiger
Staff Emeritus
Science Advisor
Gold Member
ratfink said:
Sorry to be pedantic here but this is incorrect.
The FACTS are that:
Light curves from supernovae are stretched.
Light curves from quasars are not stretched.
What do you mean they're "stretched"? Relative to what? How is this different from saying they're "dilated"? If you wish to be very precise, we should say:

- Assuming no evolution or observational biases, the power spectra of light curves from supernovae are consistent with cosmological time dilation.
- Ditto for GRBs.
- Not so for quasars.

I'm not saying that the quasar "fact" above is unreliable as compared to the others. In fact, it's probably more reliable than the GRB measurements.

Now some people say that the stretching of supernovae Ia light curves is explained by 'time dilation' and that the non stretching of quasar light curves is an 'exotic effect!"
Most likely, it's due to ordinary evolution of quasars in the universe, an effect that is in no way exotic. I was simply trying to allow for unconventional ("exotic") ideas, like Garth's theory.

Others wonder why they cherry pick.
Cherry pick what? The observations are all being considered. Please specify which part of the interpretation you didn't understand.

Nereid
Staff Emeritus
Science Advisor
Gold Member
Plates (and facts)

In his paper, Hawkins references an earlier one by him (Hawkins, M. R. S., 1996. MNRAS, 278, 787), which contains more details of raw data, the data reduction techniques etc. I will dig that up (if no one beats me to it), and check, but in the meantime, I'm guessing it simply says (in more detail) what's already in the Hawkins paper: plates were taken, and measured by an automated system (that's been thoroughly shaken down), producing ~24x600 pairs of estimates (magnitude, mid-time of exposure), together with estimates of both measurement error (per pair) and systematic error (possibly per plate, or region of each plate). There will be ~18x400 similar pairs (for the red plates).

Independently, from other work, there will be >600 estimates of redshift, at least one for each quasar.

Hawkins would have fed the magnitude/epoch pairs into a (standard?) Fourier transform software package (possibly one tailored for astronomical observations), and produced ~1,000 Fourier power spectra (~600 blue and ~400 red).

Other than checking that all this work was done properly (which no one really doubts), there's not much point duplicating it.1

Fast forward to this "fact":
ratfink said:
Light curves from quasars are not stretched.
First, without a 'sanity check' (or 'quality control') of the kind I outlined above, even the analysis which Hawkins did (let alone the conclusions) has a weak foundation. Ergo, any conclusion ('fact') is, strictly speaking 'provisional'.

Second, as SpaceTiger has said (and as I've pointed to), even accepting the approach Hawkins took (without checking by deploying a different approach), the Hawkins results need only to have modest increases in their error bars and the 'fact' itself becomes marginal.

But the worst part of this 'fact' is, as several people have already pointed out, it is based on the assumption that apples are oranges (a.k.a. 'quasars' are a homogeneous class of astronomical object which undergo no evolution).

Compare this with Type 1a SNe - they are not only all apples, nor even all granny smith apples, but they all come from the same state in the great country of Australia (though maybe one or two come from New Zealand).

There may be ways to disentangle evolution from the Hawkins data (the Fourier power spectra), by assuming certain things about that evolution (e.g. that it is pure luminosity evolution). However, you can't do that from the data presented in the published paper - you need the actual spectra (or, better, the ~24x600 + ~18x400 magnitude-epoch data pairs).

Now, if ratfink (or any other PF member) is interested in examining 'facts' in terms of non-mainstream theories (or, worse, crackpot ideas), then we enter territory that few 'alternativists' willingly enter - re-interpretation of huge parts of standard astrophysics (I note, for the record, that Garth has shown a good appreciation of at least some of the issues involved in going down this path).

If you wish, ratfink (or any other PF member wishes), we can embark on a trip to disentangle 'facts' from 'theory', using the above quote from ratfink as our guide.

In the meantime, I intend to outline some ideas on the nature of quasars, how such might affect variability throughout their evolution, and how we could go about building some quasar simulations to test various ideas about what we might observe (in observations like those Hawkins reports).

1As I indicated earlier, there are some checks that I think would be worthwhile, at this level (crudely, how were the faintest observations handled), but they'd likely result in, at worst, dropping a few marginal quasars, and maybe making the error bars a bit bigger on as much as a significant minority of the rest.

Last edited: