Galaxies without dark matter halos?

Joseph Lazio wrote in message ...
"TS" == Thomas Smid writes:

TS Joseph Lazio wrote in message
TS ...

You're mixing up two different measurements. Within the optical
disk, I think gas and stars usually co-rotate. (....) Outside the
optical disk, no stars are detected so one has to rely on the gas
to trace the gravitational potential.

TS The fact remains that in most publications gas rotation curves are
TS used to support the hypothesis that stars are bound by dark
TS matter. Why ? Presumably because star rotation curves wouldn't be
TS as conclusive.

Oh, come on. That's a fairly serious charge, deliberate suppression
of data. Surely you provide some illustrative examples?

As mentioned, just about any textbook about galaxies and dark matter
proves my point. The latest textbook I could find (Galaxies in the
Universe, by Sparke and Gallagher) was published in 2000 (so there is
no excuse for not taking the more recent recent results into account).
Yet, the relevant chapter about dark matter still discusses only HI
gas rotation curves despite the obvious fact that gas should be pretty
much irrelevant for the overall dynamics of a galaxy. Again, why not
publish star rotation curves if they are indeed equivalent to the gas
rotation curves ? If not a deliberate suppression, then this certainly
has to be considered as a serious error of judgment in editing the
publication (also for older publications).



O.k., I've taken a look at your Web site, and don't understand one
crucial point. You spend a lot of time working out the force from a
magnetic field on ionized gas. Yet most (all?) of the gas
measurements in the outer parts of galaxies are of neutral gas. The
Lorentz force is F = q (v x B), so the Lorentz force on a neutral
hydrogen atom (q = 0) is F = 0. (I'll also conveniently ignore that
Vega-Beltran's work focused on *ionized* gas and he found general
agreement with stellar motions.)

You did not read my webpage (
http://www.physicsmyths.org.uk/darkmatter.htm ) properly: each neutral
atom becomes ionized at some stage of its existence. It is then that
it is trapped and accelerated by the magnetic field. Once the ion has
recombined and becomes neutral again, it will maintain the tangential
speed imparted by the magnetic field. Hence, eventually all the
neutral gas will show a tangential speed corresponding to the rotation
of the magnetic field lines.


I wouldn't call the existence of dark matter a foregone conclusion
either. There are a number of astronomers quite uncomfortable with
the entire dark matter and dark energy paradigm that's developed over
the past 5 years or so. Unfortunately, genuflections in the direction
of unknown magnetic fields aren't enough. Either some huge systematic
mistake(s) has been made or the Universe really does work like this.

As mentioned already , in addition to the influence of magnetic fields
on gas rotation curves, errors in the mass-luminosity relationship
could also explain any discrepancies attributed presently to dark