From: dwells@fits.cv.nrao.edu (Don Wells)
Subject: Re: Supermassive stars and HD limit (was Big Bang...)
Organization: nrao
	<DWELLS.92Aug26000759@fits.cv.nrao.edu> <Bttp9M.1DA@well.sf.ca.us>
Date: Fri, 11 Sep 1992 15:21:30 GMT

 dwells@fits.cv.nrao.edu (Don Wells) writes:
 > If your Meta-Theory has trouble explaining contiguous, collimated, *bright*
 > structures with sizes of kiloparsecs that occur in galaxies, then maybe its
 > "engine" needs to be rebuilt!  :-)

In article <Bttp9M.1DA@well.sf.ca.us> metares@well.sf.ca.us (Tom Van
Flandern) writes:
 TVF> I have said in previous posts that I am untroubled by several-
 TVF> kiloparsec-length jets.  Supermassive stars should be able to
 TVF> produce jets several orders of magnitude bigger than the Crab
 TVF> pulsar jets...

The plasma jets produced by the nuclei of radio galaxies and quasars
are highly directional, a fact which implies a (highly) preferred
direction in the "engine" (whatever it may be). Black holes have
strong angular momentum, a vector quantity. Section III.D.5
"Hydromagnetic Jets" of Mitchel C. Begelman, Roger D.  Blandford and
Martin J. Rees, "Theory of Extragalactic Radio Sources", Rev. Mod.
Phys. 56:255, 1984, discusses mechanisms by which that angular
momentum may produce and control a high-velocity flow aligned with the
vector. The vector defines a stable preferred direction, which
explains how jets are able to flow in the same direction for long
periods of time (see III.D.8 "Jet Axis").  The discussions of your
postulated supermassive stars have not mentioned any properties which
could produce jet directionality and collimation in an equally
natural, intuitive fashion.  This is a fundamental problem for the
Meta model.

You have said that the outer regions of the postulated Meta-model
"stars" are not particularly hot or energetic. This means that they
have no mechanism to generate the high-velocity flows which we
observe. In particular, the stars cannot generate flows with high
Lorentz factors.  (Sections III.D.6 "Electron-Positron Jets" and
III.D.7 "Can Ultrarelatavistic jets be generated?" deal with this
problem in the standard model.)  This is a fundamental problem for the
Meta-Model.

The power conveyed by and radiated by the jets is very high, and it is
sustained for long periods of time, which implies that AGN "engines"
must be quite efficient.  Even M87 and M84 (comparatively low-powered
jets) pose serious power problems for the Meta-Model. By comparison,
the mechanisms discussed in III.D.* of BB&R are able to extract large
amounts of power from black holes with high efficiency, and deliver it
into plasma jets, as long as the mass accretion flow continues. The
lack of an efficient means to produce *powerful* plasma jets is a
fundamental problem for the Meta-Model.

 TVF> ...the standard model must explain jets of high-redshift quasars
 TVF> which are megaparsecs in length, "the largest contiguous
 TVF> structures in the universe". Which model has the greater
 TVF> difficulty in explaining the scale of the jets without ad hoc
 TVF> postulates?  

The principal "ad-hoc" postulate of the standard model is that black
holes exist, in accordance with General Relativity.  The holes can
produce vast amounts of power, sustained over vast periods of time,
with a natural directionality mechanism. Given this sort of "engine",
the projection of well-collimated jets over distances of hundreds of
kiloparsecs, even megaparsecs, is a logical consequence of the
standard model.

The Meta-Model encounters a *major* difficulty when it tries to
explain the dimensions of the jets in radio galaxies. For example,
consider plate 47 of ApJ Supplement volume 72, figure 3 of O'Donoghue,
Owen and Eilek, ApJ Suppl. 72, 79 (1990). The plate shows radio
contours of the jet source 0043+201 superimposed on a CCD image,
exactly on top of a cD (giant elliptical galaxy) in the richness=3
cluster Abell 98.  Numerous other (radio-quiet) cluster galaxies are
visible around the cD which is producing the jets, and the size of the
jets can be compared with the sizes and separations of the galaxies.

An optical observer who did not know of the existence of the radio
jets would classify this situation as just another richness=3 cluster
of galaxies, and would feel justified in inferring a distance to and
linear scale within the cluster from the observed redshift.  It is
clear that the pair of jets is produced by one of the galaxies of the
cluster, and so it is appropriate to also use the redshift to infer a
size for the jets.  The redshift is z=0.11; for H0=75, the projected
linear size of the jets is 290 kiloparsecs.  The source of the jets is
not a quasar, for which the Meta-Model would postulate a
non-cosmological redshift---it is a *galaxy*, whose distance is
indisputable.  This case is bad news for the Meta-Model; it
constitutes a fundamental problem for the theory.

Plates 60 (350 kpc), 65 (240 kpc), 67 (450 kpc) and 69 (440 kpc) show
other examples of Abell clusters containing jets.  The projected
linear sizes of these four jet sources can also be compared to typical
intracluster galaxy separations directly (by inspection of the CCD
images), in a context where non-cosmological redshift of the jet
sources cannot be postulated.

The morphologies of plasma jets associated with radio galaxies are
essentially identical to the morphologies of jets associated with
quasars. Radio astronomers infer, quite reasonably, that probably the
same type of "engine" powers the jets of the two types of sources. The
galaxies are at cosmological distances; the power outputs and physical
sizes of their jets are comparable to the outputs and sizes of quasar
jets, *if* the quasars are also at cosmological distances, as the
standard model presumes.  

The Meta-Model is guilty of an unneccessary ad hoc hypothesis when it
postulates that quasars are supermassive "stars" which can produce
modest (but still rather powerful) jets at much closer than
cosmological distances, at the same time that observations are telling
us that radio galaxies can produce *powerful*, *large* jets with
essentially identical morphology at cosmological distances.

 TVF> The final word for now will be yours, as I must prepare for two
 TVF> weeks of travel.  -|Tom|-  

I delayed this followup for 11 days so that it would be ready for your
return. I myself will be travelling in France during the next week.
--

Donald C. Wells             Associate Scientist        dwells@nrao.edu
National Radio Astronomy Observatory                   +1-804-296-0277
520 Edgemont Road                                 Fax= +1-804-296-0278
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