SDSS Quasars & Cosmology: Challenges to Current Models

In summary: SDSS survey are lensed." (but the very first paper by Strauss and colleagues I looked at, found a lensed object at redshift 6.2; it's not clear to me how many quasars at redshift 5.7-6.5 were in the SDSS survey, so I have no idea what fraction of them were lensed; I suspect that the fraction is not tiny, but I don't know).Also, another reason I ask is that I have no idea what "Good science requires us to change models when the models conflict with well-controlled, repeatable observations." (there is no such requirement
  • #71
Chronos said:
Even GR will eventually yield to scientific progress.

The sooner the better IMHO.

Speaking of falsifiable, anyone have a status on the LIGO's findings?

How about the CDMS project?

Gravity Probe B?

hmmm...


As for Ptolemy matching observational data, the end result is expected. When you match models to observation without conducting fasifiable experiments, it ceases to be science and instead becomes dogma.
 
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  • #72
Evolution of metallicity in galaxies ...

Here's an interesting, recent paper* that has considerable relevance to some of the broader issues turbo-1 raises in this thread:

http://arxiv.org/abs/0806.2410" [Broken]:
We present initial results of an ESO-VLT large programme (AMAZE) aimed at determining the evolution of the mass-metallicity relation at z>3 by means of deep near-IR spectroscopy. Gas metallicities are measured, for an initial sample of nine star forming galaxies at z~3.5, by means of optical nebular lines redshifted into the near-IR. Stellar masses are accurately determined by using Spitzer-IRAC data, which sample the rest-frame near-IR stellar light in these distant galaxies. When compared with previous surveys, the mass-metallicity relation inferred at z~3.5 shows an evolution much stronger than observed at lower redshifts. The evolution is prominent even in massive galaxies, indicating that z~3 is an epoch of major action in terms of star formation and metal enrichment also for massive systems. There are also indications that the metallicity evolution of low mass galaxies is stronger relative to high mass systems, an effect which can be considered the chemical version of the galaxy downsizing. The mass-metallicity relation observed at z~3.5 is difficult to reconcile with the predictions of some hierarchical evolutionary models. Such discrepancies suggest that at z>3 galaxies are assembled mostly with relatively un-evolved sub-units, i.e. small galaxies with low star formation efficiency. The bulk of the star formation and metallicity evolution probably occurs once small galaxies are already assembled into bigger systems.

At any given epoch, AGNs are rare objects, compared with galaxies.

Even today, I think it's true to say that AGNs are quite poorly understood, compared with galaxies^.

How galaxies evolve - in terms of their gas content, morphology, rate of star formation, etc, etc, etc - is a relatively recent topic in astrophysics.

Even more recent is high quality observations of high-z galaxies, which can be used to study various aspects of galaxy evolution (among other things).

Thus it's not unreasonable to expect that detailed understanding of how AGNs evolve will likely trail similar understanding of how galaxies evolve, though AGN evolution will certainly be informed by results obtained from studying galaxy evolution.

In any case, research into the formation of both AGNs and galaxies is highly constrained today by an almost complete lack of relevant observations ... about all we know is that it took place in the Dark Ages, between the surface of last scattering and the epoch of re-ionisation.

The introduction section of the Maiolino et al. paper is worth reading carefully; one gets a real sense of both excitement and of how little is yet firmly established.

The second two paras of the introduction are well worth quoting, as they illustrates well just how much, and how little, is known (plus how active a field of research this is):
Maiolino et al. said:
Various physical processes may be responsible for the mass-metallicity relation. One possibility is that outflows, generated by starburst winds, eject metal-enriched gas into the IGM preferentially out of low-mass galaxies (due to the shallow gravitational potential well),making their enrichment less effective than in massive systems (e.g. Tremonti et al., 2004; De Lucia et al., 2004; Finlator & Dav´e, 2008). An alternative scenario is that low mass systems are still at an early evolutionary stage and have still to convert most of their gas into stars, hence they are poorly metal-enriched relative massive galaxies (which are instead already evolved). This is the so-called “galaxy downsizing” scenario, supported by various observational evidences (e.g. Juneau et al., 2005; Feulner et al., 2005; Franceschini et al., 2006; Asari et al., 2007; Perez-Gonzalez et al., 2007), where massive galaxies formed most of their stars rapidly and at high redshift, while low mass systems are characterized by a slower evolution, which extends to low redshift. Finally K¨oppen et al. (2007) ascribes the mass-metallicity relation to variations of the IMF high-mass cutoff in different star forming environments.

The relative role of these processes in shaping the mass-metallicity relation is debated. It is likely that each of them contributes at least to some extent, since observational evidences have been found for all of them. Each of these factors (outflows/feedback, downsizing, IMF) has profound implications on the evolution of galaxies. Therefore, it is clear that the mass-metallicity relation contains a wealth of information useful to constrain models of galaxy formation and evolution. Indeed, any model of galaxy evolution is now required to match the mass–metallicity relation observed locally (e.g. Kobayashi et al., 2007; Brooks et al., 2007; de Rossi et al., 2007; Dav´e & Oppenheimer, 2007; Dalcanton, 2007; De Lucia et al., 2004; Tissera et al., 2005; Bouch´e et al., 2006, 2007; K¨oppen et al., 2007; Cid Fernandes et al., 2007; Finlator & Dav´e, 2008; Tassis et al., 2008). However, different models predict different evolutionary patterns of the mass-metallicity relation as a function of redshift, and observational data are required to test and discriminate among them.

We surely live in (astrophysical) exciting times! :smile:

* actually a preprint, though is apparently "in press" (A&A)
^ with the exception of extreme dwarf galaxies
 
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  • #73
Hot off the press today on astro-ph (accepted for publication in A&A):

http://arxiv.org/abs/0901.0974" [Broken]

Particularly pertinent is the comparison of model to observation which demonstrates the bias present in observing these high redshift objects (see Fig. 3). Also of interest is the carbon abundance.

The metallicity of the most distant quasars
Authors: Y. Juarez, R. Maiolino, R. Mujica, M. Pedani, S. Marinoni, T. Nagao, A. Marconi, E. Oliva
(Submitted on 8 Jan 2009)

Abstract: We investigate the metallicity of the broad line region (BLR) of a sample of 30 quasars in the redshift range 4<z<6.4, by using near-IR and optical spectra. We focus on the ratio of the broad lines (SiIV1397+OIV]1402)/CIV1549, which is a good metallicity tracer of the BLR. We find that the metallicity of the BLR is very high even in QSOs at z~6. The inferred metallicity of the BLR gas is so high (several times solar) that metal ejection or mixing with lower metallicity gas in the host galaxy is required to match the metallicities observed in local massive galaxies. On average, the observed metallicity changes neither among quasars in the observed redshift range 4<z<6.4, nor when compared with quasars at lower redshifts. We show that the apparent lack of metallicity evolution is a likely consequence of both the black hole-galaxy co-evolution and of selection effects. The data also suggest a lack of evolution in the carbon abundance, even among z>6 quasars. The latter result is puzzling, since the minimum enrichment timescale of carbon is about 1 Gyr, i.e. longer than the age of the universe at z~6.
 
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  • #74
matt.o said:
http://arxiv.org/abs/0901.0974" [Broken]
...
The data also suggest a lack of evolution in the carbon abundance, even among z>6 quasars. The latter result is puzzling, since the minimum enrichment timescale of carbon is about 1 Gyr, i.e. longer than the age of the universe at z~6.

Matt,
that is intriguing. Suppose it's true. Suppose these things are already rich in carbon at z=6.

Why does the minimum enrichment timescale have to be 1 Gyr?
Doesn't that just mean that there were some huge early stars that got in there fast and cooked up a lot of carbon real quick?

I guess what I'm asking about is the amount of wiggle in the accepted early universe carbon enrichment story.
 
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  • #75
I think it means back to the drawing board for nucleosynthesis. Metallization may have occurred much more rapidly in the early universe than we can currently explain - at least in the case of extremely bright objects. I don't perceive that as a threat to any cosmological model at present.
 
  • #76
Hi Marcus,
marcus said:
Matt,
that is intriguing. Suppose it's true. Suppose these things are already rich in carbon at z=6.

Why does the minimum enrichment timescale have to be 1 Gyr?
Doesn't that just mean that there were some huge early stars that got in there fast and cooked up a lot of carbon real quick?

I guess what I'm asking about is the amount of wiggle in the accepted early universe carbon enrichment story.

Well, apparently the carbon enrichment is due primarily to AGB (asymptotic giant branch) stars and planetary nebulae which evolve on long timescales. I think AGB stars are the end results of medium mass stars, thus take some time to evolve to a stage where they are expelling carbon. I'm not sure where they got the 1Gyr value from (I'd have to did deeper into the referenced papers), but I do know AGB stars and their feedback winds are hard to model in stellar population models (at least according to Bruzual and Charlot 2003) and thus there could be some wiggle room there.
 
  • #77
Here is a recent paper. (which matt.o has referenced)

http://arxiv.org/abs/0901.0974

The current model is that mass accretes (through whatever means - there are lots of models) the quasar fires off, and then radiates strongly enough to sweep away local gas/dust so the EM radiation from the accreting BH/quasar is visible to us. This is a wonderful model at low redshifts - not so much at high redshifts, because we still have to manage to figure out how very heavy elements might have already formed and have been incorporated into the quasars, so that we can observe them at high redshift.

If we want to believe that elements heavier than those that might have been created in the BB evolve through stellar synthesis, then perhaps there is reason to explore our options. We can't reasonably expect the (accretion/stellar synthesis/nova/accretion) cycle to explain what we see.
 
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  • #78
The form of the galaxy or cluster of galaxies is directly related to the mass and activity of the so called black hole. Black holes vary in size and activty during the evolution phases spiral to elliptical to spiral and so on with various forms in between.

Tubo the link you provided, is great reading.

The metallicity of the most distant quasars
Authors: Y. Juarez, R. Maiolino, R. Mujica, M. Pedani, S. Marinoni, T. Nagao, A. Marconi, E. Oliva
(Submitted on 8 Jan 2009)
Abstract: We investigate the metallicity of the broad line region (BLR) of a sample of 30 quasars in the redshift range 4<z<6.4, by using near-IR and optical spectra. We focus on the ratio of the broad lines (SiIV1397+OIV]1402)/CIV1549, which is a good metallicity tracer of the BLR. We find that the metallicity of the BLR is very high even in QSOs at z~6. The inferred metallicity of the BLR gas is so high (several times solar) that metal ejection or mixing with lower metallicity gas in the host galaxy is required to match the metallicities observed in local massive galaxies. On average, the observed metallicity changes neither among quasars in the observed redshift range 4<z<6.4, nor when compared with quasars at lower redshifts. We show that the apparent lack of metallicity evolution is a likely consequence of both the black hole-galaxy co-evolution and of selection effects. The data also suggest a lack of evolution in the carbon abundance, even among z>6 quasars. The latter result is puzzling, since the minimum enrichment timescale of carbon is about 1 Gyr, i.e. longer than the age of the universe at z~6.


What does this say about the age of the universe?
 
  • #79
Is there an echo in here?
 
  • #80
http://www.haltonarp.com/articles/origins_of_quasars_and_galaxy_clusters":

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.
 
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  • #81
Quasars is the term used to explain an object that looks star like.


Quasars of various sizes and origin can be found.

The extreme case is quasars that are found in the centre of cluster of galaxies, having extreme mass, a monster jet, large surrounding halo etc.

The other extreme is where a body is ejected from a black hole such as a microquasar, a star looking body.
 
  • #82
turbo-1 said:
Here is a recent paper. (which matt.o has referenced)

http://arxiv.org/abs/0901.0974

The current model is that mass accretes (through whatever means - there are lots of models) the quasar fires off, and then radiates strongly enough to sweep away local gas/dust so the EM radiation from the accreting BH/quasar is visible to us. This is a wonderful model at low redshifts - not so much at high redshifts, because we still have to manage to figure out how very heavy elements might have already formed and have been incorporated into the quasars, so that we can observe them at high redshift.

If we want to believe that elements heavier than those that might have been created in the BB evolve through stellar synthesis, then perhaps there is reason to explore our options. We can't reasonably expect the (accretion/stellar synthesis/nova/accretion) cycle to explain what we see.
The Juarez et al. preprint paints, in the Discussion section, a plausible explanation for why the inferred BLR metallicities of SDSS-selected quasars are roughly constant* (section 4.1, first para):
Juarez et al. said:
The apparent lack of evolution observed in Figs. 1–2 should not be interpreted as a lack of evolution of the BLR metallicity in individual AGNs. Indeed, Fig. 1 shows the average metallicity of the BLR in quasars that are accreting at the given redshift, but does not trace the evolutionary path of individual quasars. The apparent lack of evolution in the BLR metallicity observed in Fig. 1 likely results from a combination of the BH-galaxy coevolution and selection effects. Indeed, to cross the detection threshold of the SDSS magnitude-limited survey, high-redshift quasars must have high luminosities, hence (even if accreting at the Eddington limit) high black hole masses. Most models predict that high black holemasses must have been accompanied by the formation of a massive host galaxy (e.g. Granato et al., 2004; Di Matteo et al., 2005; Hopkins et al., 2008; Li et al., 2007), which would result into the local MBH − Mspheroid relationship. Therefore, by the time a quasar at any redshift is detectable in a magnitude-limited survey, its host galaxy must have evolved significantly and enriched its ISMsignificantly. The quasar feedback is another evolutionary effect that may yield to observational biases resulting in an apparent lack of metallicity evolution. Indeed, according to many models, during the early phases, when the host galaxy is still metal poor, the accreting black hole is embedded within the dusty ISM, and therefore difficult to detect in optical surveys. Only during the late evolutionary phases, when the galaxy is already metal rich, the quasar develops winds powerful enough to expel large quantities of gas and dust, so that the quasar becomes visible to optical observations.
The next para presents a tentative, quantitative look at this, and section 4.1 concludes:

"Summarizing, the co-evolution of black holes and galaxies, combined with observational selection effects (mostly in optical surveys), naturally explains the finding that unobscured quasars of a given luminosity appear to have on average the same metallicity at any redshift."

* do not show significant change as a function of z
 
  • #83
marcus said:
Matt,
that is intriguing. Suppose it's true. Suppose these things are already rich in carbon at z=6.

Why does the minimum enrichment timescale have to be 1 Gyr?
Doesn't that just mean that there were some huge early stars that got in there fast and cooked up a lot of carbon real quick?

I guess what I'm asking about is the amount of wiggle in the accepted early universe carbon enrichment story.
(bold added)

Juarez et al. make it clear that 'the carbon problem' needs more work before it could be said to be well-established.

The part where they discuss it - section 4.3 - is both in the Discussion section and brief (just one para long), and concludes ('this issue' is the apparent large carbon abundance in the BLR):
Juarez et al. said:
We note that this issue is independent of the size and mass of the BLR, making it just a pure timescale problem. Tackling this issue requires a more accurate determination of the carbon abundance, which may come from future high spectral resolution optical/near-IR observations or from future submm observations of far-IR fine structure lines (Maiolino, 2008).
In addition to the observational aspects, the relationship of the abundance of carbon in the BLR to that in the gas and stars of the host galaxy will need to be addressed, both observationally and theoretically (as matt.o has already noted). And the theoretical modelling will need to address some difficult questions about the behaviour of systems that have no counterparts in the local universe (as Chronos has already noted).

Its all fascinating stuff, and you can easily understand why it's a hot research topic.
 
  • #84
Suede said:
http://www.haltonarp.com/articles/origins_of_quasars_and_galaxy_clusters":

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! :devil:
 
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  • #85
From what I've been reading in the last few days, I've been getting the impression that the arguments often work as follows - I do hope this isn't really the case!

If a quasar appears to be in the middle of a galaxy, fuzzy blob or whatever, compare the redshift of the quasar and the galaxy:

1. If the quasar's redshift is higher, it must be behind the galaxy, "proving" that it is further away and hence that its redshift is cosmological.

2. If the quasar's redshift is close to that of the galaxy, it is obviously within the galaxy, "proving" that quasar redshifts are not intrinsic.

In reality, I'd hope that there would be lots of other factors taken into account, like details of spectral lines, whether the quasar appeared to be at the centre of the galaxy and so on. However, I can't help being a little suspicious.
 
  • #86
Jonathan Scott said:
From what I've been reading in the last few days, I've been getting the impression that the arguments often work as follows - I do hope this isn't really the case!

If a quasar appears to be in the middle of a galaxy, fuzzy blob or whatever, compare the redshift of the quasar and the galaxy:

1. If the quasar's redshift is higher, it must be behind the galaxy, "proving" that it is further away and hence that its redshift is cosmological.

2. If the quasar's redshift is close to that of the galaxy, it is obviously within the galaxy, "proving" that quasar redshifts are not intrinsic.

In reality, I'd hope that there would be lots of other factors taken into account, like details of spectral lines, whether the quasar appeared to be at the centre of the galaxy and so on. However, I can't help being a little suspicious.
Hi JS,

I don't know how you formed this impression! :confused:

Perhaps you could explain how, in some detail?

FWIW, your description bears only a coincidental resemblance to what contemporary standard procedure is. And as an example, let's see what Juarez et al. say, in the preprint cited in several posts in this thread, about how they measured the redshifts (etc); here is section 2 (Observations) in its entirety (some formatting and characters may be lost):
Juarez et al. said:
We observed a sample of 30 high-redshift quasars (4.0 < z < 6.4) from the SDSS by means of near-IR and optical spectra covering at least the UV rest-frame emission lines SiIVλ1397+OIV]λ1402 and CIVλ1549, but in most cases the spectra extend to λrest ∼ 3000 − 4000Å. The original goal of most of the observations was to constrain the dust extinction in high-z QSOs. A more detailed description of the data and the results on the dust extinction will be given in Gallerani et al. (in prep.). Here we only focus on a byproduct, namely the evolution of the BLR metallicity based on the (SiIV+OIV)/CIV ratio.

Observations were obtained both with the Italian Telescopio Nazionale Galileo (TNG) in Spain and with the Very Large Telescope (VLT)-ESO in Chile. Observations were performed in several observing runs from 2003 to 2005. The observations at the TNG were obtained with the Near Infrared Camera Spectrograph (NICS) mostly with the Amici prism to obtain spectra in the range 0.9-2.3 μm at R∼75. This low-resolution mode is excellent for investigating the QSO continuum shape, but also for detecting broad emission lines. Some QSOs were observed again with the IJ grism to obtain 0.9-1.45 μm spectra at R∼500. Typical integration times ranged from ∼20 minutes to ∼3 hours. The observing strategy and data reduction are similar to those discussed in Maiolino et al. (2004).

The spectroscopic observations at ESO-VLT were done with the FORS2, along with the grismGRIS150I, to observe the range 6000-11000 Å at R∼300. These observations are mostly used to cover the short-wavelength part of some of the quasar spectra not properly sampled by the near-IR observations, but we also specifically observed a few quasars with no near-IR data with the specific aim of measuring the (SiIV+OIV)/CIV ratio. The total exposure times range from 30 to 60 minutes. For some of the z < 5 quasars observed with NICS, for which no FORS2 observations were available, we combine our near-IR spectra with optical data taken from Anderson et al. (2001).
Perhaps you are unfamiliar with the term "BLR"? It stands for "broad line region" and is not resolved in images of any quasar (that I know of), nor in the UV/optical/nearIR waveband images of any AGN either* (and, for completeness, if you can't resolve/separate something in an image, you certainly can't take a separate spectrum of it!).

Maybe a read of Maiolino et al. (2004) would help you?

* IIRC; if anyone knows of any reported observations of an AGN's resolved BLR ...
 
  • #87
Nereid said:
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! :devil:

Plasmoid ejection from current pinches is a well known laboratory proven phenomina.

btw,

The Discovery of a High Redshift X-ray Emitting QSO Very Close to the Nucleus of NGC 7319
Pasquale Galianni, E.M. Burbidge, H. Arp, V. Junkkarinen, G. Burbidge, Stefano Zibetti
Astrophys.J. 620 (2005) 88-94
http://arxiv.org/abs/astro-ph/0409215

A strong X-ray source only 8" from the nucleus of the Sy2 galaxy NGC 7319 in Stephan's Quintet has been discovered by Chandra. We have identified the optical counterpart and show it is a QSO with $z_e = 2.114$. It is also a ULX with $L_x = 1.5 x 10^{40} erg sec^{-1}$. From the optical spectra of the QSO and interstellar gas in the galaxy (z = .022) we show that it is very likely that the QSO and the gas are interacting.




Probably just another freak coincidence though.

like this, NGC 7319:

041001quasar-galaxy.jpg



or this, NGC 4319:

http://www.answersingenesis.org/images/quasar.jpg [Broken]

or this, NGC 7603:

ngc7603-show.jpg
 
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  • #88
Suede said:
Nereid said:
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!
Plasmoid ejection from current pinches is a well known laboratory proven phenomina.
In which the following have been 'proven'*:
- the creation of mass?
- atoms, nuclei, and electrons whose mass decreases with time?
- violation of conservation of momentum, energy, and angular momentum?
- violation of at least two of the laws of thermodynamics?

Not to mention that no lab has ever performed a controlled experiment on an object of mass 10^6 (or more) sols, in a volume of 1 kpc^3 (or more).

Suede, this is beyond absurd.

btw,

The Discovery of a High Redshift X-ray Emitting QSO Very Close to the Nucleus of NGC 7319
Pasquale Galianni, E.M. Burbidge, H. Arp, V. Junkkarinen, G. Burbidge, Stefano Zibetti
Astrophys.J. 620 (2005) 88-94
http://arxiv.org/abs/astro-ph/0409215

A strong X-ray source only 8" from the nucleus of the Sy2 galaxy NGC 7319 in Stephan's Quintet has been discovered by Chandra. We have identified the optical counterpart and show it is a QSO with $z_e = 2.114$. It is also a ULX with $L_x = 1.5 x 10^{40} erg sec^{-1}$. From the optical spectra of the QSO and interstellar gas in the galaxy (z = .022) we show that it is very likely that the QSO and the gas are interacting.
Yep, that's a well-known, and much discussed paper.

As with many (most?) of these Arp (et al.) papers, the 'very likely interacting' interpretation rests almost entirely on perceived alignments of features in images ... and where it doesn't, it requires a) an 'intrinsic redshift' that has no counterpart in standard physics**, and b) the 'interacting' material to have no intermediate redshift (which is inconsistent with the Arp idea you posted earlier). Further, with the widespread and easy availability of codes to model the interaction between a compact high-mass object and a galaxy, it's curious that no Arp et al. paper has been published showing the plausibility of the purported 'interaction' via simulation (with or without variable mass, etc).

Applying Occam's razor, and keeping in mind the huge amount of solid research showing that AGNs are a homogeneous class of object, we can conclude that this quasar is being viewed through NGC 7319.

* these are all core aspects of Arp's idea
** no one has published a paper showing that the Wolf effect, to take just one example, is consistent with all well-established features in the relevant spectra, for example
 
  • #89
I'm not going to argue Arp's theory with you because doing so will result in me getting banned from these boards, which I'm sure would please you greatly.

Its enough to say I believe him and the theories that support his claim are scientifically credible, rely on known plasma physics, and don't postulate any hypothetical matters and energies.

btw,

http://www.skepticalinvestigations.org/controversies/images/NGC4319.jpg [Broken]
 
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  • #90
Arp has contributed great works in many fields.

Which part has been proven wrong?

It is not very scientific just saying that he has been proven wrong.


Neried quote

Suede, this is beyond absurd.


btw,

The Discovery of a High Redshift X-ray Emitting QSO Very Close to the Nucleus of NGC 7319
Pasquale Galianni, E.M. Burbidge, H. Arp, V. Junkkarinen, G. Burbidge, Stefano Zibetti
Astrophys.J. 620 (2005) 88-94
http://arxiv.org/abs/astro-ph/0409215

A strong X-ray source only 8" from the nucleus of the Sy2 galaxy NGC 7319 in Stephan's Quintet has been discovered by Chandra. We have identified the optical counterpart and show it is a QSO with $z_e = 2.114$. It is also a ULX with $L_x = 1.5 x 10^{40} erg sec^{-1}$. From the optical spectra of the QSO and interstellar gas in the galaxy (z = .022) we show that it is very likely that the QSO and the gas are interacting.


Which part is absurd?
 
  • #91
Sundance said:
Arp has contributed great works in many fields.

Which part has been proven wrong?

It is not very scientific just saying that he has been proven wrong. Neried quote
Suede, this is beyond absurd.btw,

The Discovery of a High Redshift X-ray Emitting QSO Very Close to the Nucleus of NGC 7319
Pasquale Galianni, E.M. Burbidge, H. Arp, V. Junkkarinen, G. Burbidge, Stefano Zibetti
Astrophys.J. 620 (2005) 88-94
http://arxiv.org/abs/astro-ph/0409215

A strong X-ray source only 8" from the nucleus of the Sy2 galaxy NGC 7319 in Stephan's Quintet has been discovered by Chandra. We have identified the optical counterpart and show it is a QSO with $z_e = 2.114$. It is also a ULX with $L_x = 1.5 x 10^{40} erg sec^{-1}$. From the optical spectra of the QSO and interstellar gas in the galaxy (z = .022) we show that it is very likely that the QSO and the gas are interacting.

Which part is absurd?
First of all Sundance, I'd appreciate it if you quote me correctly.

Let's follow the sequence, leaving out the [ QUOTE ] tags.

In https://www.physicsforums.com/showpost.php?p=2027652&postcount=80", Suede wrote (this is the entire post, minus the link in the first line):
= = = = = = = = = = Suede, post #80 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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.
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

My post #84 followed, and quoted Suede's (#80) in full (I have left it out here):
= = = = = = = = = = Nereid, post #84 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
[Suede's post#80]

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! :devil:
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

Suede replied, in https://www.physicsforums.com/showpost.php?p=2028094&postcount=87", and quoted just one line of my post #84. He edited this at least once, and my reply (post#88, see below) - which quoted his #87 post - did not include the parts he added subsequently. Here is post #87, up to the phrase "btw,":
= = = = = = = = = = Suede, post #87 (part only) = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
[from Nereid's post#84: 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! :devil:]

Plasmoid ejection from current pinches is a well known laboratory proven phenomina.

btw,

[rest of Suede's post #87 omitted]
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

My https://www.physicsforums.com/showpost.php?p=2028121&postcount=88" followed. It contains two parts, and quotes Suede's post#87 in full. I shall reproduce only the first part, since it is the only part germane to my reconstruction. The embedded quote is reconstructed sequentially; the relevant footnote is moved up.
= = = = = = = = = = Nereid, post #88 (part only) = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
[from Nereid's post#84: 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! ]
[from Suede's post#87: Plasmoid ejection from current pinches is a well known laboratory proven phenomina.]

In which the following have been 'proven'*:
- the creation of mass?
- atoms, nuclei, and electrons whose mass decreases with time?
- violation of conservation of momentum, energy, and angular momentum?
- violation of at least two of the laws of thermodynamics?

Not to mention that no lab has ever performed a controlled experiment on an object of mass 10^6 (or more) sols, in a volume of 1 kpc^3 (or more).

Suede, this is beyond absurd.

* these are all core aspects of Arp's idea
[rest of Nereid's post #88 omitted]
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

I think it's pretty clear that what I meant by 'beyond absurd' is that Suede's presentation of Arp's ideas in post#80 is beyond absurd when tested using Suede's own 'laboratory proof' criteria.

At no point did I say that the 2005 Galianni et al. paper was absurd. If you have somehow read that into what I wrote, then I trust that this post corrects your misunderstanding; if it does not, please do me the courtesy of saying so, and asking for further clarification.

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?
 
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  • #92
All of your points have been accounted for in the theories that support Arps work.

Of course, I can't discuss them here because that will get me banned.

So it seems underhanded to attack those theories when I can't post any proof in defense of them.

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



So what do you think about this?

http://www.skepticalinvestigations.org/controversies/images/NGC4319.jpg [Broken]
 
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  • #93
Sometimes we need papers to state the obvious.


Evidence for Activity in the Spiral Galaxy NGC4319
Sulentic, J. W. Observational Evidence of Activity in Galaxies: Proceedings of the 121st Symposium of the International Astronomical Union, held in Byurakan, Armenia, U.S.S.R., June 3-7, 1986.
http://articles.adsabs.harvard.edu/full/1987IAUS..121..483S

Radio and optical evidence for activity in the spiral galaxy NGC 4319 is presented. NGC 4319 appears to be one of the first spirals to exhibit double lobe radio structure outside of the nuclear regions. The optical data show that (1) the quasar M205 is connected to the nucleus of NGC 4319 and (2) that a similarly connected region on the opposite side of the nucleus is expanding towards us with V ≡ 103km s-1. It is suggested that the unusual Hα/[N II] λ6583 ratio (≤0.3) indicates that the entire central (7 kpc diameter) disk of NGC 4319 has been shock excited by this activity.
 
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  • #94
Suede said:
Sometimes we need papers to state the obvious.

http://adsabs.harvard.edu/cgi-bin/n......398..495B&db_key=AST&high=3d6e3bdf3c21424"
The near-ultraviolet spectrum of Markarian 205
Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Hartig, George F.; Jenkins, Edward B.
We report measurements of the absorption and of the emission lines between 1600 and 3200 A in the spectrum of the nearby AGN Markarian 205 (z = 0.071), which lies at a projected distance of 3 kpc (H0 = 100 km/s) from the nucleus of the nearby barred spiral galaxy, NGC 4319 (z = 0.0047). The results were obtained using high-resolution (R = 1300) observations with the Faint Object Spectrograph of the HST. A total of 15 absorption lines, 13 of which are produced by Galactic gas, and four AGN emission lines are detected. Two of the absorption lines, the Mg II resonant doublet, are produced by gas in the intervening galaxy NGC 4319. This is the first detection of absorption due to intervening gas in this famous quasar-galaxy pair.
 
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  • #95
Suede said:
[snip]

So what do you think about this?

http://www.skepticalinvestigations.org/controversies/images/NGC4319.jpg [Broken]
[/URL]
My first thought was "what is the source?"

My next thought was "without knowing the source, I can't be sure, but there's a high likelihood that the source has a clearly stated policy on use and (public) reproduction, if not an actual copyright."

That was followed by "hmm, PF has a clearly stated policy on this, doesn't it?"

And so I went to check.

And it is so:
Copyright Guidelines:
Copyright infringement is illegal. Physics Forums will enforce the law. Never post an article in its entirety. When posting copyrighted material, please use small sections or link to the article. When posting copyrighted material please give credit to the author in your post.

Further, another of PF's rules states, in part (bold added):
It is against our Posting Guidelines to discuss, in most of the PF forums, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion.

So my next thought was "Suede surely knows about this rule by now, so there's a very good chance that this image is taken from such a publication. In my experience, all such publications have clear guidelines on use, including, at minimum, an acknowledgment of the source. So, it's likely that Suede has goofed in not following PF's rules, or is posting material from a source other than a peer-reviewed publication."

And that lead me to my next action: to click on the REPORT button, to report the post for violation of PF's rules.
 
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  • #96
Jonathan Scott said:
From what I've been reading in the last few days, I've been getting the impression that the arguments often work as follows - I do hope this isn't really the case!

If a quasar appears to be in the middle of a galaxy, fuzzy blob or whatever, compare the redshift of the quasar and the galaxy:

1. If the quasar's redshift is higher, it must be behind the galaxy, "proving" that it is further away and hence that its redshift is cosmological.

2. If the quasar's redshift is close to that of the galaxy, it is obviously within the galaxy, "proving" that quasar redshifts are not intrinsic.

In reality, I'd hope that there would be lots of other factors taken into account, like details of spectral lines, whether the quasar appeared to be at the centre of the galaxy and so on. However, I can't help being a little suspicious.
The way that you'd actually test whether it's within or behind the galaxy would be to look for absorption spectra. If it's behind the galaxy, it will show absorption lines in its spectrum that are of the same redshift as the galaxy. If, on the other hand, it's within the galaxy, and there is dust in the galaxy between us and the quasar, then it should show absorption of the same redshift.

Typically very high-redshift quasars are so far away that their light passes through a large number of intervening gas clouds. Thus they have absorption spectra that are all over the place. Of particular interest is what is known as the Lyman-alpha forest: since most of the intervening matter is in the form of neutral hydrogen, the primary absorption is from the biggest hydrogen line: the Lyman alpha line (this is the line from the transition between the ground state and the first excited state). With these far-away quasars, the large number of intervening gas clouds at a wide range of redshifts basically kills a large portion of the spectrum of the quasar. It's basically impossible to account for the existence of the Lyman-alpha forest in Arp's model.
 
  • #97
Suede said:
So what do you think about this?

http://www.skepticalinvestigations.org/controversies/images/NGC4319.jpg [Broken]
[/URL]
That so-called "luminous bridge" is an artifact of the way the data is gathered. Basically, if a telescope takes a picture of a point source, the optics of the telescope spread that image out into a blob. The size of the blob is called the "beam size" of the telescope, and it determines the resolution available.

The apparent connection between those two objects is clearly an effect of this beam. Obviously no competent astronomer had a hand in annotating that image.
 
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  • #98
Would you like another opinion, published in a peer-reviewed journal? A couple of "competent astronomers" wrote this one.

http://articles.adsabs.harvard.edu/full/1987ApJ...319..687S

Nay-saying and shouting down unpopular ideas are not mature behaviors, nor should they be countenanced in "scientific" circles.
 
  • #99
Chalnoth said:
That so-called "luminous bridge" is an artifact of the way the data is gathered. Basically, if a telescope takes a picture of a point source, the optics of the telescope spread that image out into a blob. The size of the blob is called the "beam size" of the telescope, and it determines the resolution available.

The apparent connection between those two objects is clearly an effect of this beam. Obviously no competent astronomer had a hand in annotating that image.

Actually, the bridge is present in the Hubble images, too (see http://heritage.stsci.edu/2002/23/supplemental.html" [Broken]). 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.
 
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  • #100
turbo-1 said:
Would you like another opinion, published in a peer-reviewed journal? A couple of "competent astronomers" wrote this one.

http://articles.adsabs.harvard.edu/full/1987ApJ...319..687S

Nay-saying and shouting down unpopular ideas are not mature behaviors, nor should they be countenanced in "scientific" circles.
This is why higher-resolution images are so nice:

i0223cw.jpg

[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.
 
  • #101
matt.o said:
Actually, the bridge is present in the Hubble images, too (see http://heritage.stsci.edu/2002/23/supplemental.html" [Broken]). 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.
 
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  • #102
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.
 
  • #103
Suede said:
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 [Broken]
[/URL] So what?

====================================================================

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.
 
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  • #104
Chalnoth said:
This is why higher-resolution images are so nice:

i0223cw.jpg

[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.

NGC_4319_T.jpg
 
  • #105
Please ensure that this thread stays on topic. Further discussion of Arp's theories here will result in a prompt locking.
 
<h2>1. What is SDSS Quasars and how does it challenge current models?</h2><p>SDSS Quasars, or Sloan Digital Sky Survey Quasars, are a type of extremely luminous and distant objects in the universe. They emit large amounts of energy and are believed to be powered by supermassive black holes at the centers of galaxies. These objects challenge current models because their high luminosity and distance cannot be fully explained by current theories of galaxy formation and evolution.</p><h2>2. How is SDSS Quasars data collected and analyzed?</h2><p>The SDSS Quasars data is collected using a 2.5-meter telescope located in New Mexico, USA. The telescope has a specialized camera that can capture images of large areas of the sky at once. The data is then processed and analyzed using sophisticated computer algorithms to identify and study the properties of the quasars.</p><h2>3. What are some of the key findings from SDSS Quasars research?</h2><p>One of the key findings from SDSS Quasars research is that these objects are found in large numbers at very high redshifts, indicating that they were formed in the early universe. Another important finding is that the properties of quasars and their host galaxies are closely related, providing insights into the co-evolution of galaxies and their central black holes.</p><h2>4. How does the study of SDSS Quasars impact our understanding of cosmology?</h2><p>The study of SDSS Quasars has greatly impacted our understanding of cosmology by providing evidence for the existence of supermassive black holes and their role in galaxy evolution. It has also helped to refine our understanding of the large-scale structure of the universe and the distribution of matter within it.</p><h2>5. What are some of the current challenges and future directions for SDSS Quasars research?</h2><p>One of the current challenges for SDSS Quasars research is to better understand the physical processes that drive their high luminosity and energy output. Future directions for research include studying the properties of quasars at even higher redshifts and using new technologies and techniques to gain a deeper understanding of these enigmatic objects.</p>

1. What is SDSS Quasars and how does it challenge current models?

SDSS Quasars, or Sloan Digital Sky Survey Quasars, are a type of extremely luminous and distant objects in the universe. They emit large amounts of energy and are believed to be powered by supermassive black holes at the centers of galaxies. These objects challenge current models because their high luminosity and distance cannot be fully explained by current theories of galaxy formation and evolution.

2. How is SDSS Quasars data collected and analyzed?

The SDSS Quasars data is collected using a 2.5-meter telescope located in New Mexico, USA. The telescope has a specialized camera that can capture images of large areas of the sky at once. The data is then processed and analyzed using sophisticated computer algorithms to identify and study the properties of the quasars.

3. What are some of the key findings from SDSS Quasars research?

One of the key findings from SDSS Quasars research is that these objects are found in large numbers at very high redshifts, indicating that they were formed in the early universe. Another important finding is that the properties of quasars and their host galaxies are closely related, providing insights into the co-evolution of galaxies and their central black holes.

4. How does the study of SDSS Quasars impact our understanding of cosmology?

The study of SDSS Quasars has greatly impacted our understanding of cosmology by providing evidence for the existence of supermassive black holes and their role in galaxy evolution. It has also helped to refine our understanding of the large-scale structure of the universe and the distribution of matter within it.

5. What are some of the current challenges and future directions for SDSS Quasars research?

One of the current challenges for SDSS Quasars research is to better understand the physical processes that drive their high luminosity and energy output. Future directions for research include studying the properties of quasars at even higher redshifts and using new technologies and techniques to gain a deeper understanding of these enigmatic objects.

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