Good current paper on mass / luminosity and rotation curves
in [Physics]
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From: Y.Porat on 9 Jul 2010 13:23 On Jun 30, 7:52 pm, dlzc <dl...(a)cox.net> wrote: > http://arxiv.org/abs/1005.3154 > > Provides a lot of background into how Dark Matter is arrived at (as a > free parameter, whose spatial distribution is far from simple, > depending on the M/L modelled internal to the target galaxy). > > David A. Smith -------------------- see My 'Circlon'' idea !!! Y.Porat ---------------------
From: Y.Porat on 9 Jul 2010 13:35 On Jul 2, 3:48 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > On 6/30/10 12:52 PM, dlzc wrote: > > >http://arxiv.org/abs/1005.3154 > > > Provides a lot of background into how Dark Matter is arrived at (as a > > free parameter, whose spatial distribution is far from simple, > > depending on the M/L modelled internal to the target galaxy). > > > David A. Smith > > David--The case for the existence of dark matter is strong. > There is copious observational data showing way more gracvitational > influencve than can be accounted for bu baryonic matter. Background: > http://en.wikipedia.org/wiki/Dark_matter > > Quoting from Ned Wright's > http://www.astro.ucla.edu/~wright/cosmology_faq.html#DM > > What is the dark matter? > > "When astronomers add up the masses and luminosities of the stars near > the Sun, they find that there are about 3 solar masses for every 1 solar > luminosity. When they measure the total mass of clusters of galaxies and > compare that to the total luminosity of the clusters, they find about > 300 solar masses for every solar luminosity. Evidently most of the mass > in the Universe is dark. If the Universe has the critical density then > there are about 1000 solar masses for every solar luminosity, so an even > greater fraction of the Universe is dark matter. But the theory of Big > Bang nucleosynthesis says that the density of ordinary matter (anything > made from atoms) can be at most 10% of the critical density, so the > majority of the Universe does not emit light, does not scatter light, > does not absorb light, and is not even made out of atoms. It can only be > "seen" by its gravitational effects. This "non-baryonic" dark matter can > be neutrinos, if they have small masses instead of being massless, or it > can be WIMPs (Weakly Interacting Massive Particles), or it could be > primordial black holes. My nominee for the "least likely to be caught" > award goes to hypothetical stable Planck mass remnants of primordial > black holes that have evaporated due to Hawking radiation. The Hawking > radiation from the not-yet evaporated primordial black holes may be > detectable by future gamma ray telescopes, but the 20 microgram remnants > would be very hard to detect". ---------------------- th e mass of the single photon that i found is about exp-90 Kilograms it is based on Plank time emission !!!!! iow Black matter might be th e basic single photons !!! that at the same time moves naturally in a closed circle ie it can do a double movement 1 in a small or big circle 2 the center of that circle moves in addition in a straight line perpendicular to the plan of that circle -- (all together a hell ix movement !!!)) TIA Y.Porat ------------------------------
From: dlzc on 9 Jul 2010 13:42 Dear John Park: On Jul 9, 10:13 am, af...(a)FreeNet.Carleton.CA (John Park) wrote: > dlzc(dl...(a)cox.net) writes: > > On Jul 8, 3:58=A0pm, will...(a)cfa.harvard.edu (Steve Willner) wrote: > >> In article <503f477a-1472-4660-a7e7-c33085513...(a)y32g2000prc.googlegroups= > > .com>, > >> I'm still not clear exactly what distribution you are > >> suggesting, but to the extent I understand it (perhaps > >> not at all), it looks grossly unstable both gravitationally > >> and to its own pressure (given the temperature you > >> suggest below). > > > I don't see how it is gravitationally unstable, since it > > need have essentially no friction. A sea of positive > > and negative charges produce no viscosity. And as > > to temperature, we know temperatures from ionization > > of [minority] members... not so much from the "kinetic > > theory of gasses". > > Have you tried to estimate a collision frequency for > your plasma? For a density of 1 particle per cc and > a temperature of 25 x10^6 K I get that an > "electromagnetically significant collIsion" .... assuming a velocity, not an ionization state, maybe. This stuff is (if it exists) bound to the galaxy. I do expect that the stuff that lies in/near the galactic plane to be primarily in neutral state, but the stuff that crosses the ecliptic not to be. > (i.e. an approach to within a distance comparable to > the diameter of a hydrogen atom--so one could expect > bremstrahlen or recombination) would happen > something like once per week per particle. Such a > plasma isn't going to last more than a few decades, let > alone the age of the galaxy. Yet we have that now. I think you are ignoring the attendant electrons, and are assuming temperature = velocity. Velocity woud only be constrained by "gravitational binding". > And what about the loss of energy as synchrotron > radiation in the galactic magnetic field? (I suspect a > time-scale of a few years again, but from a very > crude estimate.) The plasma is netural. I expect contributions from the attendant electrons to cancel that out. I don't find that unreasonable. David A. Smith
From: dlzc on 9 Jul 2010 13:48 Dear Y.Porat: On Jul 9, 10:23 am, "Y.Porat" <y.y.po...(a)gmail.com> wrote: > On Jun 30, 7:52 pm, dlzc <dl...(a)cox.net> wrote: > > >http://arxiv.org/abs/1005.3154 > > > Provides a lot of background into how Dark > > Matter is arrived at (as a free parameter, > > whose spatial distribution is far from > > simple, depending on the M/L modelled > > internal to the target galaxy). > > -------------------- > see My 'Circlon'' idea !!! > Y.Porat > --------------------- Doesn't work, even if light had mass. The mass is bound to galaxies, and there is not enough gravity to do that far from black holes. David A. Smith
From: eric gisse on 9 Jul 2010 14:13
John Park wrote: > dlzc (dlzc1(a)cox.net) writes: >> Dear Steve Willner: >> >> On Jul 8, 3:58=A0pm, will...(a)cfa.harvard.edu (Steve Willner) wrote: >>> In article >>> <503f477a-1472-4660-a7e7-c33085513...(a)y32g2000prc.googlegroups= >> .com>, >>> >>> =A0dlzc<dl...(a)cox.net> writes: >>> > I've seen what the mass distribution needs to be >>> > for Andromeda, will that do? >>> >>> > -8- spin it around the "-", and orient them along the >>> > axis of rotation of the spiral galaxy. =A0Not a torus, >>> > obviously. >>> >>> What's your source for this? >> >> Andromeda shows DM up to about 60%r, above and below the galactic >> plane. >> >>> I'm still not clear exactly what distribution you are >>> suggesting, but to the extent I understand it (perhaps >>> not at all), it looks grossly unstable both gravitationally >>> and to its own pressure (given the temperature you >>> suggest below). >> >> I don't see how it is gravitationally unstable, since it need have >> essentially no friction. A sea of positive and negative charges >> produce no viscosity. And as to temperature, we know temperatures >> from ionization of moniority members... not so much from the "kinetic >> theory of gasses". > > Have you tried to estimate a collision frequency for your plasma? Obviously not. > For a > density of 1 particle per cc and a temperature of 25 x10^6 K I get that an > "electromagnetically significant collIsion" (i.e. an approach to > within a distance comparable to the diameter of a hydrogen atom--so one > could expect bremstrahlen or recombination) would happen something like > once per week per particle. Such a plasma isn't going to last more than a > few decades, let alone the age of the galaxy. While I had not taken a shot at calculating that, the result sounds rather reasonable to me. This is why I said I expect that there would be a low persistent background glow from such a distribution of Hydrogen. > > And what about the loss of energy as synchrotron radiation in the > galactic magnetic field? (I suspect a time-scale of a few years again, but > from a very crude estimate.) I had mentioned this, too. I expect though, given the field strength is in the neighborhood of a nanotesla, that backscatter radiation from collisions is more energy-sapping than synchrotron radiation. But I imagine either one would do it over galactic timescales - the 'dark matter' would have long since condensed and recombined. > > --John Park |