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Dear Nereid and Phobos (seat belt on) can we talk about redshifts?

  1. Jun 19, 2004 #1

    turbo

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    Yes, Russ, I'm strapped in for the ride, but I think it's a worthy prospect. I truly would like to discuss the problems that arise when strict interpretations of redshift=recessional velocity=distance are applied to every visible extra-galactic body. We need to get beyond this. I don't think all of Arp and Burbidge's ideas are perfectly developed, but their observations are valid and worthy of discussion.
     
  2. jcsd
  3. Jun 19, 2004 #2

    Nereid

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    I just posted a response to the moving of the other thread to TD; it's rushed and I'm not at all happy with what I wrote.

    Phobos, chroot: is there some way we can cut&paste turbo-1's two excellent posts, and Phobos' reply, into this thread? It's a great shame the other thread was, in fact, at least three different ones :uhh:
     
  4. Jun 20, 2004 #3
    This is the last paper of Arp in Arxiv. It can be interesting for the discussion
    http://arxiv.org/abs/astro-ph/0401103
    New optical spectra and general discussion on the nature of ULX's
    Authors: H. Arp, C. M. Gutierrez, M. Lopez-Corredoira
    Comments: submitted to A&A, 8 pages, 5 ps/eps figures

    "We present spectroscopic observations of three Ultra Luminous X-ray sources (ULX's). Two of them are very close to the active galaxy NGC 720 and the other is near NGC 1073. The two around NGC 720 turn out to be quasars at z=0.964 and z= 2.216, the one near NGC 1073 seems to be associated to an HII region at the redshift of NGC 1073. We concentrate our analysis on the two quasars and analyze them in conjunction with a set of 20 additional X-ray sources close to nearby galaxies which also fit the criteria of ULX's and which also have been identified as quasars of medium to high redshift. This sample shows an unusually large fraction of rare BL Lac type objects. The high redshifts of these ULX's and their close proximity to their low redshift, supposedly parent galaxies is a surprising result in the light of standard models. We describe the main properties of each of these objects and their parent galaxy, and briefly discuss possible interpretations."




    I don't think that Arp is a crackpot, he did a good catalogue of extragalactic objects. But his ideas about intrinsic redshifts seems plain wrong to me.

    PS: I've read the article, and at the end of it there's this phrase:
    "Another suggested explanation for these association of galaxies and quasars with different redshifts is mesolensing by King objects"

    What's mesolensing? What are King objects? I've never heard of that
     
    Last edited: Jun 20, 2004
  5. Jun 20, 2004 #4
    are these folks trying to discount Harp's interpretations? they don't say outright, only something about "previously proposed ideas"
    http://arxiv.org/abs/astro-ph/0310296

    can they use their models to predict the redshift differences between the apparenty associated quasar images?

    reading the paper, it seems badly translated and parts of it i can't make sense of
    grammatically, and yup, the math is over my head, it being optics and gravity and such.

    yes, and what is a KING OBJECT, can't find anything about it

    edit:
    http://scitation.aip.org/getabs/ser...00041000004000436000001&idtype=cvips&gifs=yes

    i guess they are supposed high mass objects in the halos of galaxies??
    or are they lots of mass spread out over large areas in the halo?
     
    Last edited: Jun 20, 2004
  6. Jun 20, 2004 #5

    turbo

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    mesolensing

    Mesolensing is in between microlensing (point-like mass) and macrolensing (galactic-like mass) and has been proposed as a means by which to indirectly observe CDM. The means proposed is to observe multipli-imaged quasars and to record any phasing anomalies, and from those infer the mass and/or extent of the CDM doing the lensing.

    King objects aren't a class or type of object, if I understand correctly, they are objects that conform to a particular model of mass distribution, and they have been invoked in the form of galactic halos to explain away the statistical preference in some studies for quasars to appear in closer (angular) proximity to galaxies than can be accounted for by chance.
     
    Last edited: Jun 20, 2004
  7. Jun 20, 2004 #6
    Can somebody tell what are the indications that
    the two quasars are at nearly equal distance from us?

    Are there firm indications?
     
  8. Jun 20, 2004 #7

    turbo

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    Interacting objects of disparate redshifts.

    Seyfert galaxy NGC 7603 z=0.029 is connected to its apparently ejected companion z=0.057 by a luminous bridge in which are embedded two compact emission line objects of z=0.243 and 0.391. Scroll down to the images for a look, then read the paper.

    http://arxiv.org/abs/astro-ph/0203466

    Conservative astronomers claim that these compact high redshift objects are at the distances implied by the Hubble redshift model and the filament is coincidentally projected over them. They also claim that the companion 7603B is at the cosmological distance implied by its redshift which raises the question: Why is there a luminous bridge connecting the two objects if they are too far apart to interact?

    A similar question may be asked of M51 and its companion NGC 5195. The conventional answer is that NGC 5195 interacted with M51 a long time ago and is now much farther away, as implied by its redshift. This explanation falls apart pretty readily when viewing deep exposures of the pair, as there is significant tidal action evident, and large masses of material have been displaced from the arms of M51, apparently by the ejection of NGC 5195. Notice the bright blue regions on the inner arm and how they extend out along the path of ejection toward NGC 5195. The path of ejection is apparently in the plane of M51 and not oriented away from us.

    http://housefly.astro.princeton.edu/~rhl/PrettyPictures/M51-4x4.jpg

    There are many, many more examples of small high-redshift companions interacting with lower-redshift parent galaxies. The conventionalists can explain away individual examples by positing that the the smaller companions are now farther away than the parent galaxies because they have been moving away from us since the (long-ago) interactions. There is a fatal flaw in this thinking: it places us (the observer) in the most special place in the whole universe because the paths taken by these companions all point away from us as implied by their excess redshifts relative to the host galaxies. This simply cannot be true.

    It should be evident from these two cases alone that equating redshift with cosmological distance is problematic at best. There are many more examples of interacting high-redshift objects with larger lower-redshift galaxies, though, and I will keep trotting them out, if necessary. If anybody would like to show us a small physically-interacting companion with a LOWER redshift than its host galaxy, please post a link.

    What are the benefits of exploring alternative causes of redshifts? The most obvious benefits would be the "normalization" of quasars. If quasars are at the extreme distances implied by their redshifts, they must each possess the luminosity of thousands of galaxies. Furthermore, since many of them exhibit very short-term brightness variations, they cannot be very large - perhaps smaller in extent than our solar system. Since quasars are presumed to be very early, old objects, they must be tremendously organized and concentrated clumps of matter formed very shortly after the Big Bang. What kind of object can be smaller than our solar system and exhibit the energy output of a thousand galaxies, each containing billions of stars? And how could they have organized themselves so readily in such a short period of time? These are very real problems. Big Bang cosmologists have painted themselves into a corner with these outlandish quasar properties, and the corner gets tighter with every "farthest quasar yet" announcement.

    To preserve the Big Bang, many are willing to embrace the existence of such implausible monsters. I find the existence of inherent redshifts far easier to stomach. The real question at this point is: what can cause inherent redshift in quasars and other objects? I lean toward a purely gravitational causation because of its simplicity, but the astronomical community needs to address the issue honestly and with some dedication before we can make progress in this regard.
     
    Last edited: Jun 21, 2004
  9. Jun 20, 2004 #8
    hey, somebody school me on some astronomy!

    in this pic http://housefly.astro.princeton.edu/~rhl/PrettyPictures/M51-4x4.jpg

    these are two galaxies right?
    they must be relatively close to each other to be in the same frame and similar in size? am i wrong? is that not how it works? if they were the same distance apart as say the milky way and andromeda, could someone in another galaxy snap that shot of us from the right angle? Would the milky way and andromeda have similar or different redshifts from that perspective?

    Just seeing if anyone has answers to these questions.
     
  10. Jun 20, 2004 #9
    i've seen this paper before http://arxiv.org/PS_cache/astro-ph/pdf/0203/0203466.pdf

    when one really looks skeptically at the image, you can explain it away as coincidence that the larger object has a little tail, and the 2nd larger object just happens to be behind it, and the two smaller objects are far behind the tail

    I would need to see more examples like this to call it anything other than a coincidence.
     
  11. Jun 21, 2004 #10

    turbo

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    Yes, if someone were in the right place, they could photograph our galaxy overlapped by an arm of Andromeda. It would be obvious by the lack of distortion or disturbance of Andromeda's spiral arm, however, that the galaxies are a line-of-sight pair and not interacting.

    If you take the name of the jpg out of the URL and paste the remaining URL into your browser, you will find yourself of the Princeton Pretty Pictures page. There you will fine a MUCH-higher resolution version of the same image. Download that and look at it closely. Notice how distorted and pointed the spiral arm of M51 is close to its companion and notice all the filamentous structure around the companion. These are compelling signs of current interaction.
     
    Last edited: Jun 21, 2004
  12. Jun 21, 2004 #11

    Nereid

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    Just quickly again, and to be sure that we all have the same field of discussion.

    Question to turbo-1: the only data we need consider are apparent interactions between high and low redshift objects, which are either galaxies or quasars, right? If not, what else is in the mix, wrt the cosmological redshift-distance relationship?

    Assuming it's just apparent interactions between high and low redshift objects, here are a few preliminary remarks:
    - we will have to use statistics to examine the incidence of apparent interactions between high and low redshift objects. Why? Such apparent interactions are certainly rare among Local Group galaxies, and among Virgo cluster ones (the distances to such can be established pretty reliably, and redshifts of these - and almost all but the faintest galaxies and quasars - accurately determined). Being rare, the Arp hypothesis can be properly tested only statistically against the null hypothesis (presumably, that they are coincidences)
    - the determination of the distance of an object, independently of its redshift, is important. We should therefore take a good look at what methods are used to make distance estimates, their domains of applicability, the accuracy and consistency of such estimates, etc (this is a fascinating topic of its own)
    - galaxies interact gravitationally (duh!), and plenty of them collide. This means that there will be ‘local’ motion of galaxies – the Milky Way toward M31 (Andromeda galaxy), LMC and SMC in orbit around the Milky Way, and so on. Within a cluster, these local motions can be analysed to produce estimates of the total mass within the cluster (assumptions apply); the redshifts which arise from local motion are not part of the expansion of the universe
    - quasars and AGNs: we should look at the current models, and discuss the evidence that quasars ‘live’ in galaxies (or, that quasars are ‘merely’ the active nuclei of some galaxies)

    Re NGC 7603 and López-Corredoira and Gutiérrez’ paper: IIRC, this was discussed earlier here in GA&C in PF; I think I posted links to HST observations of this object (so we could see for ourselves what the high-z emission line objects look like, at greater spatial resolution), and commented that their calculations of probability (that such an alignment in a filament would arise by chance) were flawed, principally because they didn’t take account of the fact that fainter objects are distributed in a non-uniform way across the sky. In a sense, what López-Corredoira and Gutiérrez did is analogous to assuming that high latitude interstellar absorption is uniform (we know – thanks to IRAS – that it’s not; there are intricate ‘interstellar cirrus’ clouds!)
     
  13. Jun 21, 2004 #12

    Phobos

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    Now that the thread is in the TD forum, I can't mess with it. Chroot?
    For now, here's a link to the TD parent of this spinoff thread...
    https://www.physicsforums.com/showthread.php?t=29666&page=1&pp=15
     
  14. Jun 21, 2004 #13

    Nereid

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    I believe that the SMC meets your requirements: it has a radial velocity wrt the centre of the Milky Way of -30 km/sec (i.e. a blueshift). The Magellanic Stream provides strong evidence that it's physically interacting with the Milky Way, and it most certainly is small!

    But perhaps this isn't what you meant; would you care to re-state?
     
  15. Jun 21, 2004 #14

    turbo

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    Ground-rules

    Yes, I think it's appropriate and sufficient to look at apparently-interacting bodies of discordant redshifts. By discordant, I mean a difference significant enough to rule out physical interaction if the objects are presumed to be at the cosmological distances suggested by their redshifts. If even one pair of objects has sufficiently-discordant redshifts to rule out the possibility of interaction and they are observably connected and/or interacting, then the policy of placing every object at the distance dictated by its redshift is negated. I know that there is a cadre of prominent astronomers that have been working at this for many years, but there have been a lot of factors muddying the waters, too, including egos and old grievances. I hope that there can be a rational discourse on the subject on PF, and if there are serious problems with arguments on either side, they can be talked over without anybody fearing the loss of their funding or position. I am an amateur observer/astrophotographer and have no real stake in these cosmology issues.

    Nereid - your suggestion of using the SMC and the Milky Way is interesting, :rolleyes: since the redshift component is due to the proper motion of the SMC toward us. That's not what I had in mind, though - you knew that, but I don't mind being tweaked for imprecise statements. The core problem - there are objects like M51 and its companion that are evidently interacting, but have disparate redshifts. If similar pairs are observed, the smaller companion should be travelling toward us (as opposed to away from us) as suggested by its redshift, about 50% of the time. My request was for examples of apparently-interacting pairs where the smaller component has a lower redshift than the host galaxy. If the interactions are real, and the smaller components have predominantly higher redshifts than the host, we must conclude on the basis of cosmological redshift that ejection phenomena and collision events always throw the smaller object away from us - an impossibility.
     
    Last edited: Jun 21, 2004
  16. Jun 21, 2004 #15
    I asked this question on one of the other threads somehow related to this one. But this topic got spread all over.

    It's a dummy, layman question about the optics of the whole apparently-connected-disparate-redshift objects discussion.

    It seemed there were a few papers cited (above, in this thread?) that claimed to explain the "Arp objects" as a result of gravitational lensing.

    If I were an expert in gravitational lensing, would I expect to see distortion within the images of the quasars? I have seen numerous examples of grav. lensing effects and they are all distorted into arcs or streaks. The "Einstein cross" looks like normal intact objects, but how much "refining" do astronomers do to their data when constructing an image like that? Or are the normal visible images not so "retouched." I'm sure these are stupid questions.

    I guess what I'm asking is are these papers claiming to be able to predict the nature of images collected by Arp? Or, are they merely offering an alternative explanation for these observations?
     
  17. Jun 21, 2004 #16

    turbo

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    Lensing has been cited, yes, but the more insidious claims have been the claims of statistical bias. It goes like this: Arp thinks quasars might be ejected from Seyferts and other active galaxies so he searches around them for quasars, and when he finds them, the finds are automatically statistically invalid because he had the temerity to look there. The conventional view claims that he found an apparent excess of quasars around AGN's simply because he looked near them, and if he would just search all the rest of the sky (he might be too old to pull this one off... :uhh:) his observations would fall apart. One problem with this is that the conventionalists explain away every example of discordant redshifts with the claim that Arp's methodology is flawed. Not just Arp, by the way, but the handful of observational astronomers who are still questioning the inflexibility of the redshift=distance rule.

    Then when Arp observes that the *highest-redshift* quasars in apparent ejection chains are nearest the active galaxy and the quasars with higher angular separation tend to have less excess redshift, this is also explained away as a statistical problem due to his careless selection of quasar candidates. The problem with the argument of the nay-sayers is that if a significant percentage (and not EVERY SINGLE ONE) of the quasar chains *are* oriented with the higher-redshift quasars nearer the host galaxy, a really significant cosmological problem presents itself. The quasars have somehow conspired to arrange themselves so that if plotted by redshift=cosmological distance, they have lined themselves up in inverted cosmological V's pointing directly away from us. It places us, the observers, in the most special place in the universe, which is impossible.

    I don't want to wander too far afield, here, though. If we can discuss the evidently interacting pairs of objects in light of their redshifts, it should keep the discussion focussed...well at least maybe it won't turn into a free-for-all. :smile:
     
    Last edited: Jun 21, 2004
  18. Jun 21, 2004 #17
    Turb,

    I have read that there are photos of galaxies and apparently associated quasars where the red shifts are concordant. What would be the special significance of these? (maybe quasar shot out sideways?)

    Should there not be an occasional quasar that is slightly blueshifted? (if the shifts were entirely cosmological then that would never happen)
     
    Last edited: Jun 21, 2004
  19. Jun 22, 2004 #18

    Nereid

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  20. Jun 22, 2004 #19
    turbo-1, speaking of statistics, how many of these objects have been found so far?

    quartodeciman, I don't think they have found enough objects like this to find the one quasar that is being ejected toward us. Also, if the redshift is not attributable to the motion toward or away from us (as Arp claims) then we would also never see a blue shifted quasar "comin' at us".

    Also, turbo-1, you say that the redshift seems to be a function of the distance to the galaxy? Can this be explained in terms of gravitational lensing? Again, where is the distortion? (And, of course, lenses have distortions to answer an earlier post, and I'd hope that astronomers correct for them, otherwise this is all a waste of time. After that, where are the distortions normally caused by gravitational lensing?)
     
  21. Jun 22, 2004 #20

    Nereid

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    Unified model of AGN

    This page has a brief overview of the unified model of active galactic nuclei (AGN), and includes a (very) brief summary of some of the key terms we'll likely encounter - Seyferts (Types 1 and 2), BL Lac objects, AGN, BLR, NLR, accretion disk, jet, ... (be sure to click on the links!).

    There are lots of other observations which are now falling into place, wrt this unified model; e.g. 'dark quasars' (X-ray objects that have no optical - or radio - counterpart; X-ray spectrum resembles highly obscured quasar).

    Lastly, a nice picture of a molecular torus of an AGN.
     
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