SDSS Quasars & Cosmology: Challenges to Current Models

[Chalnoth]

Actually, the bridge is present in the Hubble images, too (see http://heritage.stsci.edu/2002/23/supplemental.html" ). To some extent, you are right about the PSF issue and seeing (especially given that image was taken by an amateur astronomer) enhancing this "bridge". However, I don't think the conclusions jumped to by Arp et al. hold any ground given the paper I linked above (Bahcall et al.) and the fact that if you click on the .gif movie in the link above you can see Markarian 205's host galaxy (amongst other things like the overwhelming amount of evidence in support of redshift \propto distance). You can also see the host galaxy in the second image in the link, along with a compact companion galaxy which is not resolved in the image Suede posted, therefore adding to the "bridge" luminosity.

Heh. Posted just as you were posting. Well, clearly even the original image shows that there is something there. But the point is that it isn't a bridge: it only appears to be because of the beam of the telescope. As can be much more clearly seen in the Hubble image, it's more of a diffuse structure, as we see elsewhere around the galaxy.

 

[turbo]

What is this mysterious "beam" of a telescope that allows you to selectively ignore artifacts that you do not wish to see? As an optician, I am unfamiliar with this "oh-so-cooperative" feature that you invoke so frequently.

 

[Astronuc]

All of your points have been accounted for in the theories that support Arps work.

. . . . You saying they lack laboratory proof does not make it so. I got a professional engineering organization with 365,000 members that says otherwise.

I would say that this is misrepresenting a professional engineering organization.

So what do you think about this?

http://www.skepticalinvestigations.org/controversies/images/NGC4319.jpg

[/URL] So what?

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Other references state that NGC4319 is 80 million ly from Earth while Mrk 205 is roughly 1 billion ly away. Higher resolution images apparently show no bridge, which could be an optical effects. Apparently there is another galaxy, nearby that may have interacted with NGC4319.

NGC 4319 is 80 million light-years from Earth. Markarian 205 (Mrk 205) is more than 14 times farther away, residing 1 billion light-years from Earth. The apparent close alignment of Mrk 205 and NGC 4319 is simply a matter of chance. Astronomers used two methods to determine the distances to these objects. First, they measured how their light has been stretched in space due to the universe's expansion. Then they measured how much the ultraviolet light from Mrk 205 dimmed as it passed through the interstellar gas of NGC 4319.

http://hubblesite.org/newscenter/archive/releases/2002/23/image/a/

Markarian 205 was reported by Weedman as a Seyfert nucleus appearing within the arms of the lower-redshift spiral galaxy NGC 4319. Most of the argument here has centered on whether or not there is a visible connection between the two. Pictures were published with and without a bridge (Arp once said that he had pictures that showed no bridge as well, and didn't want to be thought lacking in observational skill). There was some early discussion of photographic proximity effects creating false bridges between bright objects, but it doesn't go away with linear detectors. Various reports were given by Arp 1971 (ApLett 9,1), Lynds and Millikan 1972 (ApJLett 176, L5), Stockton et al 1979 (ApJ 231, 673), and Sulentic 1983 (ApJLett 265, L49). Cecil and Stockton (1985 ApJ 288, 201) used CCD data from Mauna Kea to show that there is definitely some kind of luminous object between Mkn 205 and NGC 4319, stating that "Arp was correct in his insistence that his broad-band plates showed luminous intervening material. The opposite conclusions of his critics were - depending on their degree of qualification - either wrong, misleading, or irrelevant." They go on to say that Mkn 205 itself has a companion 3.3 arcseconds away, and that a tidal feature attributable to this interaction probably accounts for much of the luminous connection. More problematic is the evidence that this connection winds its way all the way into the nucleus of NGC 4319 (Sulentic 1983). Furthermore, it belongs to the very select set of galaxies with peculiar, nonstellar ionization of gas throughout the disk (Sulentic and Arp 1987 ApJ 319, 693). I must point out that NGC 4319 has a bright elliptical companion which is usually outside the area of published pictures and might be responsible for some of its morphological woes. This system is well shown (though nothing much new shows up relevant to the redshift issue) in the Hubble Heritage image, shown below as is and with a brightness stretch to bring out the intervening material.

. . . .

http://www.astr.ua.edu/keel/galaxies/arp.html

What's the issue about the redshifts?

NGC 4319 has a redshift (the fractional amount that observed wavelengths of spectral lines in a galaxy are shifted relative to the wavelengths at rest, (lobs - l rest) / lrest ) of 0.00468, while Mrk 205 has a redshift of 0.071. If redshifts imply distance, as almost all astronomers believe, then Mrk 205 is almost 15 times farther away than NGC 4319.

Mrk 205 is projected in the sky within the spiral arms of NGC 4319. In 1971 Halton Arp, who compiled an important catalog of peculiar galaxies called the Arp Catalog, wondered if this is not just a chance superposition, but rather evidence that the quasar-like galaxy really lies within NGC 4319. He found support for this view in the filamentary structure between the two objects.

If this were so, then redshifts would not be distance indicators in all cases. Needless to say it was a radical suggestion that, if true, would have upset some of the fundamental tenets of cosmology. It stirred up a lot of controversy about the meaning of redshifts and whether they were "cosmological," that is, due to the universal expansion, in all cases. Arp found numerous other examples of quasars near galaxies, although few as dramatic as this one.

In the view of most astronomers, the juxtapositions are just due to chance. The filamentary connection became less convincing as better images became available. John Bahcall and collaborators made a noteworthy contribution when they showed that NGC 4319 absorbs some of the light from Mrk 205, just as expected if NGC 4319 is projected in front of Mrk 205 (Astrophysical Journal 1992). In time, many quasars were found to lie in galaxies with exactly the same redshift, providing powerful evidence that quasars are an event that occurs in the nucleus of galaxies.

Today the redshift controversy has almost faded from view. Only a few astronomers still think there is reasonable evidence for noncosmological redshifts; a recent summary making their case was published by Geoffrey Burbidge (Publications of the Astronomical Society of the Pacific 2001). The vast majority of astronomers think that the evidence is overwhelming that redshifts show distances to objects in the expanding universe.

http://heritage.stsci.edu/2002/23/supplemental.html

NGC 4319 and MK 205 - Galaxies in Draco
An Example of the possible Quasar Red Shift Controversy.
http://www.kopernik.org/images/archive/n4319.htm

. . . . Arp contends that there is a light bridge connecting these two galaxies, so they must be at the same distance. Recent Hubble Space Telescope spectra show an absorption feature in the spectra of MK 205 that is in fact at the same red shift as NGC 4319. This would seem to show that MK 205 is in deed a much more distant object with some of it's light being absorbed as it passes through NGC 4319. This controversy is sure to be the subject or research in the future.

 

[Suede]

This is why higher-resolution images are so nice:

[click for source]

So clearly the answer is no, they weren't. Now, Halton Arp was, at one time, a competent astronomer. At some point he fell off the deep end. This is something that appears to happen to a disturbingly large number of scientists as they get older, and I have no idea why.

Actually, they are.

reprocessed images of the HST photo show a clear bridge.

 

[cristo]

Please ensure that this thread stays on topic. Further discussion of Arp's theories here will result in a prompt locking.

 

[Chalnoth]

What is this mysterious "beam" of a telescope that allows you to selectively ignore artifacts that you do not wish to see? As an optician, I am unfamiliar with this "oh-so-cooperative" feature that you invoke so frequently.

Did you not notice how the "filament" almost entirely disappeared once we had higher resolution images available? That's how we can be certain it was (mostly) just an image artifact.

Edit: Sorry, the above was not posted when I clicked "reply". I will refrain from further discussion of this.

 

[Nereid]

(bold added)

Arp's theory:

Quasars are proto-galaxies ejected from parent galaxies.

Redshift of quasars is a function of galactic aging.

Younger quasars have high redshifts, as they mature after ejection, they become lower redshift.


hmmm... seems to fit with the data at a lot of levels no?

I'm sure we could poke holes in it, but its certainly interesting to note the problems in the data such a theory would solve.

Arp's ideas on quasars can be left to enjoy their well-deserved, and well-earned, retirement, in the pages of the book Ideas In Astronomy That Didn't Pan Out.

In its simplest, highly summarised, form: quasars are AGNs, just as Seyfert 1s, blazars, type 2 quasars, etc, etc, etc are. They are a homogeneous class of astronomical object. Their observed redshifts are reliable indicators of their distance (in time and space), not least because dozens of (strongly) lensed quasars have been found.

Of the order of half the Strauss video, and accompanying powerpoint slides, that turbo-1 introduces in this thread, is taken up with presentation of (then) recent observational results that strengthen "The canonical modern picture of active galaxy structure" (to quote the title of slide 70). In addition, in the video Strauss talks about the Gunn-Peterson trough and how the signature of the end of the Dark Ages can be seen in the spectra of high-z quasars (just as predicted over 35 years ago, from standard cosmological models).

Oh, and as a side note, Arp's ideas on quasars must surely count as spectacular failures when subject to the Suede 'laboratory proof' test!

I do not wish to have this thread derailed by a discussion of the Arp-Narlikar variable mass hypothesis, nor by a discussion of papers reporting apparent relationships between high-z objects and low-z galaxies, etc. If a PF mentor considers either discussion to be within PF's guidelines, let's have a separate thread on each.

In any case, I shall not post any further, in this thread, on papers that present non-mainstream theories or ideas, and/or which are not part of current professional mainstream scientific discussion.

Finally, it would seem that you, Sundance, may not be aware of just how enormous and compelling the published papers on quasars are, and the vast quantity of high quality observations on which the contemporary 'unified AGN model' is built (I gave a short para summary in post#84). If you'd like to explore that more, I'd be happy to help you ... why not start a new thread on it?

Looks like the thread's now well and truly hijacked, eh?

Re NGC 4319 and Markarian 205: turbo-1, is there enough data, in the source (FITS) files, of the images presented or referenced in this thread so far for you to be able to do an analysis, to show consistency between them (and where they seem to be inconsistent)?

As I count, there are two reproduced in the 1987 Arp & Sulentic ApJ paper, two in the 1987 Sulentic IAU document, several from the HST (and an unknown number from the unknown source).

Are there any other readers who have expertise in (digital, astronomical) image analysis?

 

[Nereid]

Please ensure that this thread stays on topic. Further discussion of Arp's theories here will result in a prompt locking.

Oops; I was writing my post as you posted yours cristo. Apologies.

 

[turbo]

Please cite some peer-reviewed papers that describe how this "beam" effect arises, and its relation to the aperture/focal ratio of the instrument. You have cited this several times and it is brand-new to me. Of course, my interest in optics only goes back a few decades, and there may be some brand-new modifications of which I am unaware. I am willing to be educated.

 

[Chalnoth]

Please cite some peer-reviewed papers that describe how this "beam" effect arises, and its relation to the aperture/focal ratio of the instrument. You have cited this several times and it is brand-new to me. Of course, my interest in optics only goes back a few decades, and there may be some brand-new modifications of which I am unaware. I am willing to be educated.

Well, I suppose this I can talk about without any reference to Arp's theories, so I'll answer it.

First, I'd like to apologize. The terminology "beam" is actually not used in optical astronomy. I work in CMB physics, so I tend to use radio/microwave terminology. In optical astronomy, the effect is called the Point Spread Function, often simply abbreviated as "PSF". You can read more up on the theory there.

Edit: Usually the PSF of an optical telescope is determined by observing stars. Often it tends to vary slightly within the field, and also, for larger telescopes, will vary just depending upon the inclination of the telescope (the weight of the primary reflector causes it to distort under its own weight). The atmosphere will also cause some degree of aberration that varies with time (hence the utility of adaptive optics). So, most of the time, it's a really bad idea to make any science determinations when you're right at the limit of your PSF/beam: not only is the limit of the beam not very well determined, but it might actually vary either in time or just due to where you're looking.

 

[turbo]

Well, I suppose this I can talk about without any reference to Arp's theories, so I'll answer it.

First, I'd like to apologize. The terminology "beam" is actually not used in optical astronomy. I work in CMB physics, so I tend to use radio/microwave terminology. In optical astronomy, the effect is called the Point Spread Function, often simply abbreviated as "PSF". You can read more up on the theory there.

Please explain in plain language how optical telescopes suffer from this "beam" effect that you have invoked so frequently, and please cite some peer-reviewed papers that explain how this "defect" in optical telescopes results in "erroneous" images that you would like to discount. I'm waiting...

 

[Chalnoth]

Please explain in plain language how optical telescopes suffer from this "beam" effect that you have invoked so frequently, and please cite some peer-reviewed papers that explain how this "defect" in optical telescopes results in "erroneous" images that you would like to discount. I'm waiting...

I edited my above post. I'm not willing to talk about the Arp image specifically any longer.

 

[turbo]

I edited my above post. I'm not willing to talk about the Arp image specifically any longer.

Not willing, or not able? I have asked you to explain this "beam" effect that you keep citing, and you're ducking and dodging.

 

[cristo]

Not willing, or not able? I have asked you to explain this "beam" effect that you keep citing, and you're ducking and dodging.

Well, now he's not able, since my warning was not heeded. This thread is now closed. I may clean up and reopen tomorrow, if I've got the time.

 

[Chalnoth]

Not willing, or not able? I have asked you to explain this "beam" effect that you keep citing, and you're ducking and dodging.

See:

Please ensure that this thread stays on topic. Further discussion of Arp's theories here will result in a prompt locking.