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Thread: Discordant redshifts?

  1. #1
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    Discordant redshifts?

    Research on candidates for non-cosmological redshifts, M. Lopez-Corredoira, C. M. Gutierrez (2005), link is to arXiv abstract:

    (Abridged) The paradox of apparent optical associations of galaxies with very different redshifts, the so-called anomalous redshift problem, is around 35 years old, but is still without a clear solution and is surprisingly ignored by most of the astronomical community. Statistical correlations among the positions of these galaxies have been pointed out by several authors. Gravitational lensing by dark matter has been proposed as the cause of these correlations, although this seems to be insufficient to explain them and does not work at all for correlations with the brightest and nearest galaxies. Some of these cases may be just fortuitous associations in which background objects are close in the sky to a foreground galaxy, although the statistical mean correlations remain to be explained and some lone objects have very small probabilities of being a projection of background objects.
    The sample of discordant redshift associations given in Arp's atlas is indeed quite large, and most of the objects remain to be analysed thoroughly. For about 5 years, we have been running a project to observe some of these cases in detail, and some new anomalies have been added to those already known; For instance, in some exotic configurations such as NGC 7603 or NEQ3, which can even show bridges connecting four object with very different redshifts. Not only QSOs but also emission-line galaxies in general are found to take part in this kind of event. Other cases are analyzed: MCG 7-25-46, GC 0248+430, B2 1637+29, VV172 and Stephan's Quintet.
    This is not your typical "Arp was right!" paper. I'm interested in what CQ members think of the paper, especially the extent to which you think it's more than just "stamp collecting". My own interest is perhaps most strong on Section 7.

  2. #2
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    Jean Tate. True, the anomalous redshift problem is still amongst us. Redshift can be caused by radial velocity (Doppler shift). Redshift can be caused by gravitational potential... (Einstein's prediction and the Rebka/Pound experimental confirmation, 1960). But, not every redshift seen astronomically, must be caused by radial motion. Some may be caused by predominantly gravitational potential. Some may be caused by a combination of both. That's within the realm of physical possibilities.
    When first QSO's were seen, the two possibilities were thrown out by a number of astronomers/ physicists. The shifting of predominantly hydrogen spectral lines was soon inferred as being only from radial velocity. Those who argued that a neutron star in a gas cloud could also emit ionized hydrogen spectral lines, were subdued by arguments that the object would soon run out of gas, dim, and/or disappear. The persistence of the objects in the image field, temporally, was then a demonstration of radial
    redshift.
    Since then, we have learned that core collapse supernovae typically eject their nascent neutron stars at mean velocities of ~ 400 km/sec. The very highest transverse pulsars have velocities in excess of 2000 km/sec. These objects can travel through extended gas clouds, some light years in dimension, like a jet fighter through fog, constantly replenishing the gas supply for illumination, and persist in astrophotographs. They would drag some of the gas along with them, leaving "bridges" from their home galaxies.
    Many moons ago I gave the AAPT talk @ Harvard University (1994)..Gamma Ray Bursts.."A Halo of Neutron Stars at 400 Kiloparsecs?...and included the scenario that Supernova 1987a's pulsar (just detected this week) would, if it had an initial velocity of ~ 3000 km/sec in ~ 16,500,000 years , come crashing through the roof of the Hardvard Olney Science Center, including anybody in the ancient building then. At that speed, it would clear the atmosphere in ~ 1/10 sec and make a very bright light as it approached.
    Most strangely was an old article by Sterling Colgate in the Los Alamos Journal of Science. According to his calculations, despite the object as big as Rhode Island, with the mass of ~ one million Earths (106)..yep....it would pass through the Earth in it's entirety due to it's huge momentum, liquifying the crust...but the Earth would ultimately survive as a planet! (unfortunately humans and all lifeforms would not...) Keep looking up!
    When I finished talking, Matt Damon, and Ben Affleck, who had arrived late, vaulting over the seats in the back, were laughing. Most of the rest of the audience sat with their mouths open. (They played golf with my sisters boyfriend at Andover Country Club in Massachusetts and Matt was a student at Harvard then ).Fun.

    So, I don't dispute that a high redshift object (gravitational potential redshift ), can be associated with a low redshift galaxy (The large Magellanic Cloud, home to supernova 1987, and it's recently discovered pulsar 1987a at 165,000 light years ,are nearby objects, astronomically speaking. Some people do come hard to the truth. )

    pete

  3. #3
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    Sorry, meant to reply to this earlier. But it fell off my radar.

    Their statistical approach to predicting the probability of what they see appears to be very dubious. They assume an unrealistic distribution, then ignore clustering by assuming that any clustering will somehow magically vanish and leave the unrealistic distribution intact. I found my eyes glazing over when they tried to defend this approach with a long rant focusing on FACTS.

    Honestly it looks like another Arp is right paper to me. A few cherry picked examples with some questionable claims about what was observed, argument from incredulity and then some dubious statistics.

    As for these examples being due to a large gravitational component to the redshift. Maths says no.

  4. #4
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    Thanks pete, Shaula.

    I agree that the paper is pretty bad; my first reaction was "stamp collecting" (apologies to any philatelists here). My next was, well, they (the authors) should have been among the citizen scientists involved in the original Galaxy Zoo ... collectively we found dozens and dozens of examples ~as good as any in this paper.

    And something quite odd: in all the so-called discordant redshift systems, there are only ever two redshift systems (assuming two objects). There's nothing at all in the way of intermediate redshifts (in any "bridge" for example).

    Also, I do not understand the fixation with "quasars" ... they're just AGNs, and the galaxies they live in are not particularly strange otherwise (in general; there are exceptions).

    Shaula is right pete: any astronomical object with significant gravitational redshift is going to be small (compact) and massive. Which also means it'll be faint (compared to a galaxy), at least in the optical. Sure, supernovae - of all kinds - are bright, but we're not seeing photons from any white dwarf or neutron star surface. It's a pity that GRBs, of either kind, do not seem to have any lines, otherwise we may be able to detect graviational redshift.

    The part that is of greatest interest to me is how to estimate the chance of "cosmic coincidences" or "chance alignments"? Some time ago, Tom Bridgman looked into this, and found some interesting things ... check out his Discordant Redshifts: A Post-Mortem and the earlier blogposts he refers to. I find it curious that almost no one (that I've found so far) has tried to test various methods of estimating probability using mock datasets or real stars, galaxies, etc.

  5. #5
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    This is a presentation to be published in the proceedings of the conference "Crisis in Cosmology I", 23 to 25 June 2005. That is a couple of problems - not peer reviewed and presented at a slightly dubious conference. It may also be outdated.
    The abstract language is wrong. There have been no bridges with discordant redshifts found. What have been found are interacting galaxies with bridges of gas and stars between them. There are a few cases of quasars shining through those bridges and the 'discordant redshift' claim is that they are actually in the bridges. This is NGC 7603
    This galaxy pair has long been a cornerstone for those who are critical of the view that the universe is expanding, and advocates for Non-standard cosmology such as Halton Arp, Fred Hoyle and others [5] [6]. This is due to position of two quasars, one at each edge of the filament connecting the two galaxies, with much more redshift than either galaxy.
    Arp's methodology to find associations between distant quasars and nearer galaxies was very flawed statistically. He started with the assumption that the association existed and found examples of what he thought were those associations.
    Periodicities of Quasar Redshifts in Large Area Surveys (H. Arp, C. Fulton, D. Roscoe)
    We should emphasize that the procedure we are following is to examine apparent groups and concentrations of quasars that appear to be physically associated. In each of the cases investigated here it turns out there is a brighter, active galaxy present which is a candidate for the origin of these quasars. We then proceed to test this identification by seeing whether the disparate redshifts are brought into the order of the Karlsson formula when their redshifts are transformed to this chosen parent.
    That paper inspired my hypothetical on ISF about his probability calculations in other papers:
    To more clearly see the problem with Arp's methodology consider the following adaption of it:
    Look for images of unusual concentrations of quasars relatively near an arbitrary empty point such as the center of the concentration (making sure that there is no galaxy that point).
    If there are such images then run Arp's probability calculation. You will get the same magnitude of probability since the calculation does not depend on the nature of the central object.
    Would Arp then conclude that quasars are emitted from empty space?

  6. #6
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    Into the presentation itself.
    1. THE PROBLEM AND THE OBSERVATIONSWHICH GIVE RISE TO IT
    "The problem of apparent optical associations of galaxies with very different redshifts, the so-called anomalous redshifts[1, 2, 3], is old but still alive." is an exaggeration.
    A small group of astronomers kept a belief in anomalous redshifts alive for several decades without good enough evidence to convince the wider community that the effect existed. It was thus unsurprisingly ignored by most of the astronomical community. Extraordinary claims need extraordinary evidence.
    1.1. Phenomenology
    • "There is an excess of galaxies or QSOs with high redshifts near the centre of nearby galaxies."
      But they do not show that such an excess exists! Some examples of quasars shining through galaxies does not show they are in the galaxies.
    • "Filaments/bridges/arms apparently connecting objects with different redshifts." -
      The key word there is apparently. Once again they have to show that the quasars are in the foreground object (filaments between galaxies).
    • "The alignment of sources with different redshifts" is Arp's cherry picking.
    • "Morphological evidence of interaction such as star-forming regions," is close to wishful thinking.
      Assume that a distant galaxy or quasar is close to a nearer galaxy and attribute star-forming regions, etc. to their hypothetical interaction.

    2. NGC 7603: Their within the bridge assumption.
    3. NEQ3: Stories about quasars being ejected from or associated with galaxies.
    4. GC 0248+430 AND B2 1637+29: Disturbed galaxies have gas that they imagine to be interaction with more distant QSO. More cherry picking of examples.
    5. VV172: An example of set of galaxies that just happen to be in a line with different redshifts as if that were impossible!
    6. MCG 7-25-46 AND STEPHAN’S QUINTET: More "bridges" connecting objects with different redshifts.
    7. PROBABILITIES OF BEING BACKGROUND/FOREGROUND GALAXIES
    Confusion about "a posteriori" calculation. Whenever they assume quasars are ejected from galaxies and analyze data based on that, that is "a posteriori" calculations.
    8. GRAVITATIONAL LENSING: Irrelevant gravitational lensing section.
    9. OTHER PROBLEMS WITH QSOS REDSHIFTS: Some arguments from incredibility about QSOs. There are puzzles about QSO so they must fit our story, not the textbook story.

  7. #7
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    The part I'm most interested in is in Section 7 (I hope I don't mess the formating etc too badly):

    Quote Originally Posted by López-Corredoira&Gutiérrez
    For the calculation of this probability, we assume that the background/foreground objects are distributed according to a Poissonian distribution with the average density in any line of sight. There may be some clustering, but this does not essentially affect the numbers. A conspiracy in which our line of sight crosses several clusters of galaxies at different redshifts is not justified because the increase in probability due to the increase of density in lines of sight with clusters is compensated for by the additional factor to be multiplied to the present amount P to take into account the probability of finding clusters in the line of sight. On average, in any arbitrary line of sight in the sky, the probability will be given anyway by the Poissonian calculation of P (see further details in subsection 5.3.1 of [15])
    [15] is M. López-Corredoira, and C. M. Gutiérrez (Astron. Astrophys.,421, 407-423 (2004).

    Extract from subsection 5.3.1 (harder to get the formatting right, I had to do some edits):

    Let us assume that the clusters in the sky have the same size, , a Poissonian distribution, and the same number of galaxies up to a given magnitude, (galaxies/cluster). This is a very rough model, because it is clear that and depend on the redshift; however, for our present arguments, the estimation with mean values of and is enough. In such a case, the total number of galaxies, N, is:

    (14)

    where is the density of field galaxies (galaxies/deg2) and is the density of clusters (clusters/deg2). An example of a probability calculation would be the one to have three galaxies belonging to three different clusters in the area A (we assume that they have the same magnitude, for a simplistic calculation, although it can be generalized to any magnitude distribution), i.e. the probability of three clusters being in the line of sight multiplied by the probability of three galaxies from different clusters being in the area A of the filament given the density of galaxies in a cluster,



    (15)

    that is, the probability is lower than , which is the probability we calculated in (8). Therefore, the supposition of a line of sight with three clusters would make the probability smaller instead of larger, and similarly for a lower number of clusters.
    I think there are quite a few, um, shortcomings with this; for me, perhaps the most fundamental is that the authors don't seem to have even considered testing the Poissonian distribution assumption.

  8. #8
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    Quote Originally Posted by Jean Tate View Post
    I think there are quite a few, um, shortcomings with this; for me, perhaps the most fundamental is that the authors don't seem to have even considered testing the Poissonian distribution assumption.
    That is my biggest issue - next on the list is that they have then tried to defend it and ignore large scale structure with what looks like magical thinking (the last part of your first quote). A multiplicative factor on your Poisson distribution doesn't modify the distribution in the way clustering into filaments would.

  9. #9
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    I go with Schwarzchild....

    "The work of Hazard and Arp slowly increased the number of strange pairings and alignments, which Hoyle felt strongly must mean that quasars are expelled from galaxies at very high velocities. But he never convinced his Cambridge colleagues or the wider astronomical community... Hoyle received the [Russell] prize and delivered the lecture in Seattle at the [American Astronomical] society's April 1972 meeting. Arp took the opportunity to read a short observational paper arguing an extreme proposition: The excess redshifts were related to the age of the objects, and the atomic constants were changing with time!... [Hoyle] concluded, "This concept appears necessary if we are to understand the result reported by Arp... Martin Schwarzchild scolded the pair of them: "You are both crazy!" - From Conflict in the Cosmos, Fred Hoyle's Life in Science - Simon Mitton (2005)
    Everyone is entitled to his own opinion, but not his own facts.

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