Quasar Evolution and Fuelling Problem

Quasar evolution and the quasar fuelling problem are interrelated. This thread starts with some back ground to put the theoretical discussions in context and then will, once there is agreement on what is stated in background, provide a link to some of the new papers and observations concerning this subject.

"One Shot" Quasar Theory
There is a theory that every galaxy is active, for a short period, 10 million to 100 million years, when its super massive black hole rapidly grows. The “quasar period” of a galaxy is a 10MM to 100MM year time period when the galaxy in question produces the broad line spectrum of a “quasar”.

10 million to 100 million years is fairly short as compared to the life time of a galaxy and the universe. The "one shot" quasar theory postulates that there is a mechanism(s) that can abruptly end the quasar period of super massive black hole formation and high luminosity.

Quasar Space Density Evolution
There are no observed quasars in the current universe z=0. Moving back in time, the number of observed quasars continues to increase until it reaches a maximum around z=2.5, roughly 11 billion years in the past. The quasar "one shot" theory explains that observation, by postulating that the conditions for turning on the “quasar” period of galaxy formation were optimum 11 billion years ago.

Beyond 11 billion years ago, the number of quasars abruptly drops. The "one shot" quasar theory explains this observation as a reduction in quasar formation favourability, for the time period big bang to 11 billion years ago.

Quasar Luminosity Evolution
Observationally there is a second complication, for any quasar theory. When moving back in time the quasar average luminosity for the quasars’ “on period”, increases exponentially up to around z=2.5 and then increases at even a higher rate to the highest observed redshift quasars z=7.5.

The theories to explain the quasar luminosity evolution and quasar space density evolution are still under development. There is no current theory that can explain the full period of quasar space density evolution and luminosity evolution.

One possible mechanism to explain the increase in average quasar luminosity, as one moves back in time, is that there is an increase in the average super massive black hole mass, for the quasar “on period” as one moves back in time.

Following that hypothesis the super massive black holes for the galaxies that turned on at z=2.5 (11 billion years ago) would be more massive that the super massive black holes that turn on at z=0.5. (5 billion years in the past.) The increase in super black hole mass hypothesis, does not explain the sharp increase in quasar luminosity from z=2.5. Also quantitative analysis has indicated that a postulated increase in super massive black hole mass does not have sufficient mechanism range ability to explain the observed quasar luminosity evolution.

It is therefore necessary to add a mechanism that would enable, when the quasar turns on, to have an increase in the rate of growth of the super massive black hole, for the on time period. A quasar 4 billion years ago would therefore grow slower than a quasar 11 billion years ago. Note there still needs to be a mechanism that would limit the quasar 4 billion years ago’s on period to around 10 MM years, to explain the evolution of quasar space density.


Comment:
Translating redshift “z” to time period was done using Ned Wright's cosmo calculate (Assumed a flat universe.)

http://www.astro.ucla.edu/%7Ewright/CosmoCalc.html

This may be the paper Gordon Richards’ referred to in the presentation Spaceman Spiff linked to. (Richards said another explanation may be required for increasing quasar luminosity with redshift from z=.12 to z=2.5 rather than increasing quasar super BH mass.)

The authors of this paper use a different analytical technique to estimate quasar super massive black hole mass. The finding presented in this paper questions the reduction of quasar super massive black hole mass with decreasing z. The increase in quasar super black hole mass with increasing redshift (z) has the hypothesized reason why quasar luminosity increases with redshift up until around z=2.5.

Apparently further papers concerning this subject are forthcoming.

http://arxiv.org/PS_cache/arxiv/pdf/...801.0243v2.pdf


Mass Functions of the Active Black Holes in Distant Quasars from the Sloan Digital Sky Survey

M. Vestergaard, X. Fan, C. Tremonti, Patrick Osmer, Gordon Richards

The subject of quasar metallicity evolution with increasing redshift (lack of) and quasar dust was discussed at recent quasar symposiums. This is only one of a number of papers concerning this subject.

It is interesting that quasar spectrum show a lack of metallicity evolution with redshift. Also interesting is finding of a large amount of dust in high redshift quasars. The explanation for this finding is that the conditions in the vicinity of a quasar are ideal for SNe supernova and the formation of dust. Some of the very high redshift quasars have supersolar metallicity of 1 to 10 times.

http://arxiv.org/abs/astro-ph/0603261v1

Metals and dust in high redshift AGNs by R. Maiolino et al.

The author Xiaohui Fan in a quasar presentation mentioned a recent discovery of quasar clustering and quasar binaries (This I believe is the paper he was referring to.) Fan's presentation was the first I have heard of quasar clustering. I did not know there were quasar binaries. I am not sure what to make of this finding.

http://arxiv.org/abs/0709.3474

"Quasar Clustering from a Complete Sample of Binaries" by Adam Myers, Gordon Richards, Robert Brunner, Donald Schneider, Natalie Strand, Patrick Hall, Jeffrey Blomquist, and Donald York

PHL 1811, Lineless highly luminous quasar

PHL 1811 is the second brightest observed object at z=0.191. PH 1811 is interesting due to its high luminosity, as it is a lineless quasar (another term for a lineless quasar is “Naked" quasar).

When lineless quasars were first discovered it was hypothesized that they were formed when two Seyfert galaxies merged, and the quasar core of one the Seyfert galaxies was ejected. The logic of that hypothesis was that the ejected quasar core would lose the feed source for its accretion disk. The thought was that ejected quasar would continue to emit for a short period of time due to residual gas (which it was assumed would continue to in fall) that it managed to carry into intergalactic space. A consequence of the “ejected quasar core” hypothesis would be that a lineless quasar would be less luminous, not more luminous than a “standard” quasar.

The model of a quasar created using the logic and the mechanism constraints of the accretion disk quasar hypothesis must have a companion galaxy that feeds the quasar’s accretion disc. The quasar accretion disc hypothesis requires a massive gas cloud in close vicinity to the quasar as only a portion of the gas cloud can be pulled into the accretion disc. Stars will or should form in the massive gas cloud. There are a number of obvious issues to explain how a lineless bright quasar can form with the accretion disc hypothesized mechanism and accretion disc mechanism constraints.

It is asserted that the discovery of PH 1811 and other highly luminous lineless quasars disproves the quasar core ejection hypothesis to explain the lineless emission spectrum of lineless (Naked) quasars as it the second brightest quasar at z=0.2.

Comment:
1) It is has been known for some time that the largest portion of the quasar spectrum is generated by non-thermal processes.

2) As there is a set of observed quasar types, lineless, broad line emission, narrow line emission, soft x-ray, hard x-ray and so forth, the entire of set of quasar types can be examined to look for a common emission mechanism. The set of observations constrain or determine what must drive the quasar engine. If this line of logic is followed, it can be used to discover the properties and evolution of the massive object that drives quasars.

3) A better question than how are quasars fuelled, which assumes the quasar spectrum is generated by gas in falling to a traditional black hole, is what are the mechanisms and conditions that can generate the range of observed quasar spectrums.

The following is a link to Karen Leighly's et al. paper that describes the spectrum of PH 1811.

“The Intrinsically X-ray Weak Quasar PHL 1811. II. Optical and UV Spectra and Analysis”, by Karen Leighly et al.

http://arxiv.org/abs/0705.0940v1

Do you have a point to make with these posts, or an alternate theory to propose? This statement of yours,

seems to imply that you have another idea. If so, please state it. If not, do you have questions about the current theory of AGN fueling? Then please ask them, and I (and others) will try and answer.

You seem to be misunderstanding the Leighly paper. It is not discussing a "naked" AGN, but rather one with a very soft ionizing continuum:

Do you actually have questions about the paper?

__________________
"What do you care what other people think?" -- Richard Feynman
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Feynman, at the conclusion of his Challenger report

Along with this idea is that from time to time a galaxy will merge with some dwarf galaxy or protogalactic cloud, and reignite the central SMBH. It is very likely, for example, that 3C273 and all the other 'nearby' quasars fit this category. So... One Shot with occasional flareups.

__________________
Forming opinions as we speak

antoniseb: many galaxies likely went through several quasar phases. Every time there is a "wet" (gas and dust are still around and relatively cool) "major merger" (roughly equivalent masses) of two galaxies, the black holes will almost certainly feed strongly, before merging. And they will feed for some time after that as well.

__________________
"What do you care what other people think?" -- Richard Feynman
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Feynman, at the conclusion of his Challenger report

In reply to parejkoj:

The papers I linked to above are recent quasar observations and recent confirmation of observational conclusions. I would assume that as these observations are presented and discussed at recent symposiums as puzzles, that you cannot explain the observations.

I am thinking of quasars as a puzzle that was not been solved, hence, I am interested in recent quasar observations and research. I am interested in the physics and observational data concerning the MECO hypothesis that asserts that BH can theoretically have hair and that there is observational data that supports that BH do have a strong intrinsic magnetic field.

As I said, I am also interested in Bell's observations and analysis. I believe by your comment that you are not interested in Bell's observations and analysis. I would assume, if Bell's and the MECO line of logic was correct, that additional observational data would either disprove or confirm that logic train.

Do you have any thoughts concerning the recent confirmation of quasar clustering or the discovery of quasar binaries?

Lack of quasar metallicity evolution with redshift? Super solar metallicity of high z quasars?

Quasar associated dust?

Lack of time dilation for high z quasars?

Quasar evolution of luminosity with redshift? Quasar space density evolution with redshift?

Explanation as to why there are no quasars at z=0?

PHL 1811 seems to have other unusual spectral features. This is another paper on PHL 1811.

"PHL 1811: The Local Prototype of the Lineless High-z SDSS QSOs" by Karen Leighly et al.

http://arxiv.org/abs/0705.0940v1

I agree. I was speaking of the quasars from the more recent epoch though, when the mergers are much less frequent, and the population is more sparse. I was mostly commenting on this because William seemed to be setting up to argue that the close quasars (by this model) must be late forming galaxies, or perhaps something even more strange.

__________________
Forming opinions as we speak

Not necessarily. You misunderstood the Leighly paper, and apparently didn't even read the summary section, where they explain how the observed properties of that object can be described by a soft continuum. Though there are a number of things that we don't yet understand about the properties of AGN and their evolution, the big picture is very solid. Most of your "questions" about it have already been answered.

I don't know enough about MECO to comment on it very much, except to note that the only difference it has with the standard model of AGN is that the black hole is replaced by this MECO thing. Otherwise, all the other usual properties of AGN apply: cosmological distance, accretion disk, winds, jets, BLR, NLR, etc. My suspicion is that the authors (there appear to be only ~5 who ever write or cite anything related to MECO!) haven't fully explored the possibility that the accretion disk can store the magnetic fields that they claim to see.

If you want to discuss any of Bell's papers, please start a thread in the ATM section, and we can discuss it. This is not the first time I've requested you do so, instead of posting vague insinuations in the Astronomy section. If you want to bring Bell up again, do so in a new ATM thread. But I'll warn you: you're going to have a very tough time supporting his work, considering how shaky it is. But, you are very welcome to try.

Also: Bell's ideas and the MECO hypothesis have nothing to do with one another. Bell is trying (unsuccessfully) to turn cosmology on its head, while the MECO hypothesis simply replaces the central black hole with a different type of object. They cannot both be correct...

Doesn't surprise me in the slightest. Since quasars usually form during major mergers, we'd expect to find binary quasars and a clustering signal. Why do you ask?

This is still somewhat of a mystery, though the full link between quasar and galaxy formation isn't completely understood. As I said in a different thread, I don't know enough about these observations to make a significant comment. I'll eventually learn more about them, but haven't the time right now.

Unsurprising: there needs to be something to feed the monster, block the BLR and produce those PAH lines in the mid-IR. What's your problem with it?

Quasars have many spectral features, and how exactly they are linked is very complicated. Supernovae are relatively small and dominated by a small number of emission mechanisms, so identifying the time dilation signal isn't as hard. I predict that AGN time dilation will be identified in the next 5 years. Probably less than that. Right now, we don't have enough long-term. high-resolution spectroscopy, nor a complete enough understanding of the BLR.

I don't understand what you mean by this question, but I think I already essentially answered it in this thread. Do you have a more specific question about my response?

If I might ask a slightly different question with essentially the same answer: "Why are there no blue supergiant stars ( >20 solar masses) near ( <~300pc) the sun?" If you can answer that question, you should be able to answer, at least in part, your question above.

Actually, that's exactly the same paper as the one you cited above. And I already quoted part of the summary where they explained a probable mechanism for the observed spectral properties. Read their summary.

__________________
"What do you care what other people think?" -- Richard Feynman
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Feynman, at the conclusion of his Challenger report

In reply to parejkoj, Sorry parejkoj, the link I provided above was to Leighly’s second paper. This is a link to her first paper.

I agree to no longer mention "B" in this thread.

Quasar Clustering
The paper I linked to stated that there were 4 times more than random clustering of quasars. How many merges were you thinking of? I remember people arguing, four or five years ago, that there was no clustering of quasars (i.e. quasars were randomly distributed), that any quasars observed in close proximity were due to gravitational lensing. I thought the finding of quasar binaries to be interesting, from the standpoint of close proximity of the quasars in question and how the quasars must be fed. Also I thought that typically during a merger one of the BH was ejected.

BH Intrinsic Magnetic Field
The MECO associated observations which are based on 25 years of quasar observations are interesting as the observed quasar structures require an intrinsic black hole magnetic field as the structures have been observationally located between the disc and BH. An accretion disc generated magnetic field cannot create a structure in that location. A BH generated magnetic field is required. Also interesting is the comment in the paper that very strong magnetic fields create electron positron pairs in the vacuum. I will provide a link to the MECO, paper. It is necessary for you read to read the MECO paper before you comment.

High Redshift Dusty Quasars
I will provide a link to a paper that explains the theoretical problems which makes it difficult for "dust" to form, in general.

Lack of Quasar Time Dilation with Redshift/Lack of Quasar Metallicity Evolution with Redshift
I will provide a link to Hawkins paper that notes a lack of time dilation for quasars. There is as others have noted observed time dilation for super nova. The lack of quasar time dilation and the lack quasar evolution of metallicity could be viewed as a paradox.


Lineless QSO/Naked QSO
PHL 1811: The Local Prototype of the Lineless High-z SDSS QSOs, by Karen Leighly et al.

http://arxiv.org/abs/astro-ph/0402535

This is a link to Hawkins’ paper on naked AGN. PHL 1811 seems to be similar to the Naked AGN, in that it has an anomalous lack of emission lines (i.e. It is lineless.) PHL 1811 in addition to being lineless is anomalous as it “ is between 13 and 450 times fainter in X-rays than other quasars with the same UV luminosity.”

“Naked active galactic nuclei”, by M. Hawkins

http://arxiv.org/abs/astro-ph/0406163v1

This is paper is interesting and seems to be some how related to Leighly and Hawkins’ observations.

“Discovery of a bright quasar without a massive host galaxy”, by Pierre Magain et al.

http://arxiv.org/abs/astro-ph/0509433

Why won't you start a thread in the ATM section? You seem very interested in his work, and this isn't the first time you've brought Bell up...

During galaxy mergers, none, one, both, or the merged pair of black holes may be ejected. In the latest simulations, the most likely scenario is that the pair will merge, receive a small kick but settle down in the center of the new, larger galaxy.

Do you have a citation for the "no clustering" claim? Here's a paper by the Bachalls & Don Schneider from 1986, discussing the possibility that quasar pairs had been observed. I think you're just misunderstanding the research.

I've already looked at the MECO paper, but I don't have enough knowledge of GR to really comment on it: I've said this before. On the other hand, I do not yet believe the statement that the accretion disk cannot hold the magnetic field that they claim to have observed: accretion disk models have advanced significantly in the past few years, and I've seen some models that incorporate very powerful magnetic fields that are stable over long time periods.

I'll wait.

Did you even read my response above? Quasar spectra are much more complicated than SN spectra!

Again: Did you read the summary of the 2nd Leighly paper? I will not discuss this with you again until you have. They provide a very plausible explanation for how an object like PHL 1811 could produce the observed spectral features. It is quite different from the Hawkins' AGN. And "naked" doesn't mean there is no galaxy.

__________________
"What do you care what other people think?" -- Richard Feynman
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Feynman, at the conclusion of his Challenger report

Quasar Long Term Variability & Time Dilation

One of the criticisms of Hawkins’ findings that Quasars do not exhibit time dilation with redshift was that quasars are chaotic and do not exhibit periodic or structured changes. That criticism is not correct.

One of the unsolved puzzles for the quasar engine is how to adjust the mechanism to explain why quasars exhibit long term cyclic changes in intensity which gradually monotonically increase in amplitude.

For example the quasar Q0957+561 (The quasar from which a detailed of over twenty years provided evidence to support the assertion that black holes have an intrinsic magnetic field) has a medium cycle period of 405 days. The super cycle period (the luminosity changes monotonically increase) is not known but is based on observation in excess of 40 years.

Hawkins is one of the leading researchers in the study of the long cyclic changes in quasars. Hawkins found there was no time dilation with redshift of this medium term cyclic quasar variation.

This paper summaries the puzzle of the medium and long term quasar cyclic changes and attempts to explain the cyclic quasar variability with accretion disc changes. The MECO paper discusses the same issue and provides evidence for quasar structures and changes that cannot be explained by accretion disc instabilities. The MECO paper provides an alternative mechanism for the quasar.

Structure function analysis of Long-term quasar Variability, by W. DE VRIES and R.BECKER

Comment:
Hawkins' sarcastically refers to this paper in his second paper, on quasar cyclic variability in which he provides further data and analysis that confirms the finding of his 2001 paper, that the medium term quasar cyclic variation does not exhibit time dilation with redshift. The variations he notes must be studied in the frequency domain as the complete cycle is not known, rather than the time domain, as the above authors did. He notes that if time dilation is forced on quasar spectrum that mathematical manipulation creates a brake in the spectrum which would be not be in agreement with quasar theory with the disc accretion mechanism.

It is only recently with multiwave length observations that it has been possible to test quasar theoretical models.

Variability in active galactic nuclei: confrontation of models with observations by M. Hawkins. M. Hawkins