Quasars: Are We Measuring Them Wrong?

[sanman]

Why is it that Quasars don't red-shift? Any ideas or speculations?

http://www.physorg.com/news190027752.html

Surely all the measurements across all these quasars can't all be wrong.

Is it possible that the Big Bang theory is wrong? Is it possible that the universe is not expanding? If so, then what are the alternatives?

What other kinds of related measurements can be taken, which would shed further light on what's going on here?

 

[Vanadium 50]

You're seeing some bad, bad reporting here.

First, QSO's have measured (quite large) redshifts.

I don't have access to the latest Hawkins paper, but what he does not do is look at a particular feature (e.g. a SN light curve) and show it does not appear more slowly in distant QSO's, but he lumps together all optical variations, does a Fourier transform and shows that the ensemble appears independent of distance.

This is a much more complicated measurement, and it is much more difficult to interpret easily. For example, the farther you go out, the brighter the QSO has to be to be observed. If bright QSOs have a different ensemble of causes of optical variation than dimmer QSO's that will bias the result. Also, if large variations (easier to see far away) have a different period than small ones, this will also bias the results. All these systematics need to be understood and corrected for.

Any sort of one line conclusion like "QSOs don't exhibit time dilation" is oversimplistic.

 

[Jonathan Scott]

I find this very interesting, as I've always felt that Arp's interpretation (that quasars are not at their redshift distances) is potentially more plausible than alternatives involving very contrived assumptions about quasar evolution exactly hiding various expected effects.

(Unfortunately I can't say the same about Arp's theories attempting to explain these observations, which don't seem to have much in common with physics as we know it).

Mike Hawkins has apparently published similar papers before, especially in 2001: arXiv:astro-ph/0105073v1 "Time Dilation and Quasar Variability". I can't see the new paper myself so I don't know what the difference is, but I'd guess it's similar but statistically stronger.

I consider this quite important because of the negative result; if this paper had shown the expected time dilation, I'm sure it would have been considered strong evidence for quasars being at their redshift distances.

It is claimed that there is evidence that quasars are at such distances because they are embedded in host galaxies of the same red shift. However, I've not seen any specific convincing reference for this. Some of these "host galaxies" turn out to be just fuzziness which does not necessarily exhibit the spectral characteristics of a galaxy, and in any case, by Arp's interpretation, the anomalous red shift of a quasar appears to decrease with time, in that when there are multiple quasars apparently emitted by the same host galaxy, the youngest ones have the largest red shift, and by the time the quasar has acquired its own fully formed galaxy, its anomalous red shift is minimal.

 

[matt.o]

I find this very interesting, as I've always felt that Arp's interpretation (that quasars are not at their redshift distances) is potentially more plausible than alternatives involving very contrived assumptions about quasar evolution exactly hiding various expected effects.

(Unfortunately I can't say the same about Arp's theories attempting to explain these observations, which don't seem to have much in common with physics as we know it).

Mike Hawkins has apparently published similar papers before, especially in 2001: arXiv:astro-ph/0105073v1 "Time Dilation and Quasar Variability". I can't see the new paper myself so I don't know what the difference is, but I'd guess it's similar but statistically stronger.

I consider this quite important because of the negative result; if this paper had shown the expected time dilation, I'm sure it would have been considered strong evidence for quasars being at their redshift distances.

I find it amazing you can jump to so many conclusions without having even read the paper. Myself, I'll wait until I have access to the whole paper before making up my mind.

It is claimed that there is evidence that quasars are at such distances because they are embedded in host galaxies of the same red shift. However, I've not seen any specific convincing reference for this.

It isn't very hard to find convincing evidence for the host galaxies if you are willing to look. Here are a couple of good examples:

http://www.astr.ua.edu/keel/agn/qsohosts.html"

http://wela.astro.ulg.ac.be/themes/dataproc/deconv/quasar/quasar_e.html"

http://www.gemini.edu/node/10980"

You can find the journal articles from the above links.

Some of these "host galaxies" turn out to be just fuzziness which does not necessarily exhibit the spectral characteristics of a galaxy, and in any case, by Arp's interpretation, the anomalous red shift of a quasar appears to decrease with time, in that when there are multiple quasars apparently emitted by the same host galaxy, the youngest ones have the largest red shift, and by the time the quasar has acquired its own fully formed galaxy, its anomalous red shift is minimal.

This is definitely not the currently held view, and as you can see from the above links, the study of quasars has moved on a bit from Arp's time.

 

[Jonathan Scott]

I find it amazing you can jump to so many conclusions without having even read the paper. Myself, I'll wait until I have access to the whole paper before making up my mind.

I'm only basing my comments on the previous paper (which I have looked at) plus the comments in the press about the new one.

It isn't very hard to find convincing evidence for the host galaxies if you are willing to look. Here are a couple of good examples:

http://www.astr.ua.edu/keel/agn/qsohosts.html"

http://wela.astro.ulg.ac.be/themes/dataproc/deconv/quasar/quasar_e.html"

http://www.gemini.edu/node/10980"

You can find the journal articles from the above links.

Thanks for the links. I'd seen the first one before and was hoping for something more convincing. The one about velocity dispersion sounds interesting, but the paper doesn't specifically mention the relative red shift of the quasar and host. However, even if it is effectively zero, that doesn't conflict with Arp's suggestion that "mature" quasars match their host galaxies.

This is definitely not the currently held view, and as you can see from the above links, the study of quasars has moved on a bit from Arp's time.

The idea that quasars appear to have been emitted from "parent" galaxies is of course controversial, but anyone can look at the pictures, and they support the idea that the further the quasar is from the "parent" galaxy, the nearer the red shift to that of the host, and the more likely it is to appear to have its own host galaxy.

 

[matt.o]

Thanks for the links. I'd seen the first one before and was hoping for something more convincing. The one about velocity dispersion sounds interesting, but the paper doesn't specifically mention the relative red shift of the quasar and host.

This is typical of Arp proponents. I have provided two links which show, counter to your claims, that quasar host galaxies do indeed exist at the quasar redshifts and are more than just "...fuzziness which does not necessarily exhibit the spectral characteristics of a galaxy, and in any case...", yet you still claim it is not convincing evidence. Perhaps you need to do some of the work yourself -- you can easily derive the redshift of the host galaxy from Figure 1 of the Watson et al. paper.

...but anyone can look at the pictures, and they support the idea that the further the quasar is from the "parent" galaxy, the nearer the red shift to that of the host, and the more likely it is to appear to have its own host galaxy.

Please provide a statistical analysis which convincingly shows this.

 

[matt.o]

http://arxiv.org/pdf/1004.1824"

 

[twofish-quant]

Not terribly convinced by this paper although it is interesting.

The problem is that I have is that the observations were taken once every several days which means that the part where the power spectrum flattens out just might be an sampling effect. If you take pictures every few days, you aren't going to see any variation of the quasar power spectrum that exist on periods less than a few days so you are going to get this artificial flattening of the power spectrum.

If the flattening of the power spectrum is due to the interval at which you are observing the quasar and not from anything that is happening at the quasar itself, then of course you are going to get the same power spectrum from nearby and far away quasars.

So my first question is "do we understand what causes the spectral energy density to flatten"?

The second problem that I have is that cosmological effects not only have dilation effects but also magnitude effects. So when you shift something from the observer frame to the quasar frame you not only have to shift things left and right, but also up and down, and they didn't seem to do that.

 

[twofish-quant]

One thing that really bothers me about the paper is that they don't mention exactly how they calculate absolute magnitude. The problem is that they point out that quasars with different intrinsic brightnesses behave differently so they just look at quasars with a specified absolute magnitude to make sure that they are looking at the same "type" of quasar. That's fine, except that the absolute magnitude formula for really distant objects has a correction to take into account GR effects including time dilation, and I would have liked some discussion as to how they handled that.

If they just did take the standard absolute magnitude formula to calculate brightnesses, then I think you are going to end up with some inconsistencies since you are comparing different types of objects.