# Thread: More from Arp et al.

1. Originally Posted by TomT
(3) Use the method which Matt mentioned, which I would call an approximate method....
They're all approximate methods, aren't they? Some are just more approximate than others. Cepheids are accepted as good approximations, but their range is limited.

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Originally Posted by TomT
By your question, I am unsure if you realize that we are talking peculiar velociy here, not total velocity. I assume you realize we are talking peculiar velocity, so the situation is as follows.
The 8 Sab/Sb galaxies are located throughout the cluster at distances from us ranging from 12.6 to 28.1 Mpc. They show peculiar velocity ranging from -577 to -1133 km.sec, with the average being -868 km/sec.
The 9 ScI galaxies are located at distances ranging from 14.9 to 23.6 Mpc and have peculiar velocities ranging from -92 to +1154 km/sec with the average being +718 km/sec.
Russell did a Kolmgorov-Smirnov (K-S) test on the 2 data sets which resulted in a .001 probability that these 2 sets have the same distribution. So the question then arises, why is there an approximately 1600 km/sec offset in peculiar velocity between these 8 of one type and 9 of the other type (8+9=17), and why is one type blueshifted and the other type redshifted?
The proposed solution is that above values are not just peculiar velocities, but peculiar velocity + a non velocity component. If the non velocity component is subtracted out, the 17 remainders will be a compatible set of peculiar velocities which the K-S test will show to be members of the same distribution, just as the position data are.

[snip]
The existence of sub-structure in the Virgo cluster weakens the Russel approach, and thus the conclusions.

For starters, the distribution from which the sample is drawn is known to be non-uniform, so just what low values from application of KS mean becomes unclear.

Secondly, with such a small sample to begin with, a re-analysis (to compare any systematic differences within sub-groups) would very likely be meaningless ... unless, for example, all the spirals could be shown to belong to the same sub-group.

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I am curious about one implication of this 'intrinsic redshift', an aspect I don't think has been explored much in this thread so far.

Suppose we were to get a mole of hydrogen from each of the two groups of spirals (the ones whose redshifts differ, systematically, per the Russel paper, by several hundred km/s) and bring them into a good lab.

Suppose we took a sample of the hydrogen, from each source, together with some hydrogen from water we passed a current through, and put each sample in a spectroscope.

Would all three samples of hydrogen show an H alpha line at 656.281 nm?

Or would the two from the intrinsically redshifted galaxies have H alpha lines at different wavelengths?

Or, to get a cleaner signal, if we collected positrons from those galaxies, would the annihilation line, observed in our lab, differ from 511 keV?

Or would the maximum energy of the betas from the decay of 3H differ from 18.6 keV?

Would the mass of a proton, from these galaxies, as measured in our lab, differ from 1.672 621 71 x 10-27 kg?

And so on.

Of course, we don't have to leave home to do some of these tests; we could get quite a few constraints on how different physics is, locally in these galaxies, by using the kind of approach Bahcall used to constrain variations in alpha over cosmological time. This kind of approach has the benefit that no telescope time is needed - I guess all the relevant data, for at least some studies of this kind, is already freely available to anyone with a broadband internet connection*.

Does anyone reading this know if any proponent of 'intrinsic redshift' has even tried something like this?

*Though you may need to live in the US, the EU, Canada, etc; I think there are some restrictions on data access wrt nationality.

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Originally Posted by Nereid
The existence of sub-structure in the Virgo cluster weakens the Russel approach, and thus the conclusions.

For starters, the distribution from which the sample is drawn is known to be non-uniform, so just what low values from application of KS mean becomes unclear.

Secondly, with such a small sample to begin with, a re-analysis (to compare any systematic differences within sub-groups) would very likely be meaningless ... unless, for example, all the spirals could be shown to belong to the same sub-group.
The above is an example of the frustration with trying to checkout Russell's results. I believe the suggestion to use the KS test came from a referee reviewing the paper. The suggestion to compare the positions of Russell's spirals with the structure found in the Mei et al paper came from Matt O.
Now that this has been done and nothing was found to contradict Russell's findings, it is suggested that the doing these investigations "would very likely be meaningless" anyway.

Does anyone reading this know if any proponent of 'intrinsic redshift' has even tried something like this?
I haven't heard of this being tried. I gave the paper a very cursory glance. Is the idea behind your question that this would be a way to test if intrinsic redshift is time dependent?

TomT

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Originally Posted by TomT
Originally Posted by Nereid
The existence of sub-structure in the Virgo cluster weakens the Russel approach, and thus the conclusions.

For starters, the distribution from which the sample is drawn is known to be non-uniform, so just what low values from application of KS mean becomes unclear.

Secondly, with such a small sample to begin with, a re-analysis (to compare any systematic differences within sub-groups) would very likely be meaningless ... unless, for example, all the spirals could be shown to belong to the same sub-group.
The above is an example of the frustration with trying to checkout Russell's results. I believe the suggestion to use the KS test came from a referee reviewing the paper. The suggestion to compare the positions of Russell's spirals with the structure found in the Mei et al paper came from Matt O.
Now that this has been done and nothing was found to contradict Russell's findings, it is suggested that the doing these investigations "would very likely be meaningless" anyway.
Perhaps I misunderstood your post #2878 ... didn't you find that the Russell spirals were distributed among four different sub-groups?

If that's so, then:

a) there are too few galaxies, in each (sub-)group, to do any meaningful analysis

b) to aggregate across sub-groups, you need to do some kind of meta-analysis ... for which I think you'll find you need different statistical tools ...

As to frustration ... that's the way it goes when you do scientific research ... if a key assumption behind an approach (in this case, that the Virgo cluster is, in a key respect, homogeneous) turns out, later, to be wrong, then you have to go back and start again. If you're lucky, you don't need to go back to the very beginning; in this case, I don't think you've been lucky.
Does anyone reading this know if any proponent of 'intrinsic redshift' has even tried something like this?
I haven't heard of this being tried. I gave the paper a very cursory glance. Is the idea behind your question that this would be a way to test if intrinsic redshift is time dependent?

TomT
Not really ... it's an approach that might be used to test the extent to which various aspects of 'local physics' (in matter in galaxies that are, in this ATM view, 'intrinsically redshifted') differ from physics in our labs.

For example, the Bahcall method would show, to a pretty accurate level, just how different alpha is, in those galaxies, from what it is in labs here.

As you know, alpha is dimensionless, and also a key parameter in modern quantum theory (QED), characterising the strength of the electromagnetic interaction.

But my point was more general: there are quite a few tests one can make, of what 'local physics' is, using nothing more than data from photons from distant objects ... and such tests are pretty easy to do, if only because there is such a wealth of high-quality data available on the web ... and there are several examples in the astronomical literature*

Here's something to think about: if all you have, wrt 'intrinsic redshifts', is a small number of marginal results, then no one will take you seriously.

OTOH, if you also have some good results which show that 'local physics' is, in fact, different (at many sigma) than it is here, you have an independent set of results that points to something potentially very interesting. An analogy: the 'solar neutrino problem'.

But, suppose that 'physics there' turns out to be the same as 'physics here', from many different, independent tests. Then 'intrinsic redshift' is more likely to be an artifact of your (small sample study) initial work.

*the CMB was warmer in the past, footprints of deep gravitational wells in x-rays from accretion disks, ...

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Originally Posted by Nereid
Perhaps I misunderstood your post #2878 ... didn't you find that the Russell spirals were distributed among four different sub-groups?

If that's so, then:

a) there are too few galaxies, in each (sub-)group, to do any meaningful analysis

b) to aggregate across sub-groups, you need to do some kind of meta-analysis ... for which I think you'll find you need different statistical tools ...

As to frustration ... that's the way it goes when you do scientific research ... if a key assumption behind an approach (in this case, that the Virgo cluster is, in a key respect, homogeneous) turns out, later, to be wrong, then you have to go back and start again. If you're lucky, you don't need to go back to the very beginning; in this case, I don't think you've been lucky.
Why would the finding of a random distribution in subgroups of the galaxy subtypes, identified as having the largest excess redshift, weaken the results?

Originally Posted by Russell
The evidence indicates that late type (Sbc and Sc) spiral galaxies tend to have excess redshift relative to early type (Sa/Sb) spirals in clusters and relative to the Hubble flow with the largest excess redshifts found for ScI type galaxies.

Cheers.

P.S. Nereid, there are some questions from earlier in this thread you haven't responded to.

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Originally Posted by Nereid
Perhaps I misunderstood your post #2878 ... didn't you find that the Russell spirals were distributed among four different sub-groups?
No. The paper states the 4 subgroups are located between 15.3 and 17.7 Mpc. Only 3 of Russell's spirals are distributed among these 4 groups. The paper shows the distance modulus distribution of these 4 groups as centered at 16.5 Mpc, with the tails of the bell shaped curve tapering off 1.2 Mpc in each direction from there. (Note: The curve shown is based on distance modulus. The distance values are calculated from the distance modulus range).

So that leaves 5 of Russell's spirals outside of this region on the near side and 9 outside on the far side, i.e. not distributed among the groups.

If that's so, then:

a) there are too few galaxies, in each (sub-)group, to do any meaningful analysis

b) to aggregate across sub-groups, you need to do some kind of meta-analysis ... for which I think you'll find you need different statistical tools ...
There is a small number of spiral galaxies in Virgo available to be analyzed this way. That is why the Virgo Cluster has been called by Russell as indicative of a non doppler component to peculiar velocity. The fact that there are many such examples (which include both cluster and field galaxies) all indicating this effect is what is being claimed to make the case more conclusive.

TomT

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Originally Posted by VanderL
Why would the finding of a random distribution in subgroups of the galaxy subtypes, identified as having the largest excess redshift, weaken the results?
Small number statistics, and you need different tools to judge aggregates of dissimilar objects.
Cheers.

P.S. Nereid, there are some questions from earlier in this thread you haven't responded to.
There are?

Well, if you'd be kind enough to point me to them (we have, what, one day left?)

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Originally Posted by Nereid
Small number statistics, and you need different tools to judge aggregates of dissimilar objects.There are?

Well, if you'd be kind enough to point me to them (we have, what, one day left?)
Is that why you suddenly started posting to this thread again? You're not seriously suggesting you missed the complaints from the proponents when you decided to walk away from this dicussion?

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Of course. Are you asserting my list of candidate galaxies has been refuted? What about my simple request for the number and catalogue designations of cepheid calibrators used to 'normalize' the data? I already spoon fed you everything necessary to justify your objections. Unfortunately, it appears I am the only one putting any 'numbers' on the table. Does redshift distance - [insert favorite] independantly determined distance ring any bells? Asking me for more numbers when you have offered none is - an interesting debating tactic. It appears I am wasting my time. I concede I am no match for your suite of preconceived, inherently unfalsifiable Arpian notions.

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Originally Posted by Thanatos
Of course. Are you asserting my list of candidate galaxies has been refuted? What about my simple request for the number and catalogue designations of cepheid calibrators used to 'normalize' the data? I already spoon fed you everything necessary to justify your objections. Unfortunately, it appears I am the only one putting any 'numbers' on the table. Does redshift distance - [insert favorite] independantly determined distance ring any bells? Asking me for more numbers when you have offered none is - an interesting debating tactic. It appears I am wasting my time. I concede I am no match for your suite of preconceived, inherently unfalsifiable Arpian notions.

Perhaps you did not see this
http://www.bautforum.com/showpost.ph...5&postcount=61
http://www.bautforum.com/showpost.ph...3&postcount=62

Originally Posted by Thanatos
It appears I am wasting my time. I concede I am no match for your suite of preconceived, inherently unfalsifiable Arpian notions.
Aaaaand, it is statements like these, especially in light of the time and effort by dgruss, Ari, Tom T, and Turbo 1 before he got aboslutely fed up and left, that are totally uncalled for!

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