SDSS Quasars & Cosmology: Challenges to Current Models

[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.