Good current paper on mass / luminosity and rotation curves
in [Physics]
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From: dlzc on 30 Jun 2010 13:52 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
From: eric gisse on 30 Jun 2010 15:04 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 You do know that's not the only evidence for dark matter, right?
From: dlzc on 30 Jun 2010 17:48 Dear eric gisse: On Jun 30, 12:04 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > 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). > > You do know that's not the only evidence for dark > matter, right? Lest we go through your list of "evidence", what you have supplied to date can be done with simply normal matter. If you have something other than rotation curves (which this paper says uses M/L), or gravitational lensing (which we both know matter alone can do, and highly ionized "sparse" normal matter is Dark for visible light and less energetic observations), I'd love to hear about it. I expressed a desire to know "how it was done", and I found a paper that describes that. It neither agrees with me (even though it describes an M/L-based model that needs no Dark Matter except outside the visible disk), nor does it disagree with you. It just drops markers in the space I was interested in investigating. I thought *you* might be interested in knowing too. As to Dark Matter: http://arxiv.org/abs/1005.4688 I wonder how you get "turbulence" with a strong Dark Matter component, neutrinos or not? David A. Smith
From: eric gisse on 30 Jun 2010 20:24 dlzc wrote: > Dear eric gisse: > > On Jun 30, 12:04 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: >> 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). >> >> You do know that's not the only evidence for dark >> matter, right? > > Lest we go through your list of "evidence", what you have supplied to > date can be done with simply normal matter. Not if you believe in electromagnetic theory. You require some very special pleads to make bulk amounts of hydrogen invisible, especially in *this* galaxy where radio isn't redshifted into oblivion. > If you have something > other than rotation curves (which this paper says uses M/L) What the paper actually says is the following: We assume that the rotation curve V(R) of the disk galaxy, for which we want to construct a mass model, is known (i.e., it has been ?observed?); as a mathematical boundary condition, we assume that the rotation curve remains flat at V_\infty out to infinite radii. Rotation curves are direct observables. The interpretation does depend on mass to luminosity ratios, which are ALSO observables. It isn't as if what the paper does is controversial to your position. You just have to explain how to fill in that rather substantial amount of dark matter with normal matter while still playing by the observed rules of electromagnetism and gravitation. > , or > gravitational lensing (which we both know matter alone can do, and > highly ionized "sparse" normal matter is Dark for visible light and > less energetic observations), I'd love to hear about it. Except normal matter isn't dark for the entire electromagnetic spectrum. Just some of it. Like has already been discussed. > > I expressed a desire to know "how it was done", and I found a paper > that describes that. It neither agrees with me (even though it > describes an M/L-based model that needs no Dark Matter except outside > the visible disk), Uh, that doesn't mean as much as you think. It takes a lot of matter to flatten out the rotation curves on the edge of a galaxy. > nor does it disagree with you. It just drops > markers in the space I was interested in investigating. I thought > *you* might be interested in knowing too. > > As to Dark Matter: > http://arxiv.org/abs/1005.4688 > I wonder how you get "turbulence" with a strong Dark Matter component, > neutrinos or not? No idea. I don't run the hydrocode simulations, or study them in sufficient detail. > > David A. Smith
From: spudnik on 30 Jun 2010 20:41
ever heard of Alfven waves?... you couldn't go anywhere in space science without them. it was a discovery about ten years ago, that about an order of magnitude of hydrogen in Universe is dihydrogen, which has no dipole moment; so, it wasn't seen, til it was looked-for. > Not if you believe in electromagnetic theory. You require some very special > pleads to make bulk amounts of hydrogen invisible, especially in *this* > galaxy where radio isn't redshifted into oblivion. thus&so: I didn't see what "last paragraph" you wrote; anyway, the summary in the paper is fairly clear (~1.8 some thing .-) > The last paragraph about the relation between surface temperature and pressure, > and radiating temperature and altitude is my translation of what I think > Miskolczi is saying in: > <http://www.met.hu/doc/idojaras/vol111001_01.pdf> thus&so: that is awfully interesting, if rather complex. anyway, I have said for years, that no-one ever bothered -- after Ahrrenius did not win the first Nobel in chemistry for his coinage of the term, glass house gasses -- to model an ordinary glass house *at a latitude.* thus, the overwhelming conception of the GCMers, that the poles will heat more than the tropics, which is quite absurd. I'd also mention the '30s paper of George Simpson, a table-top experiment with a Bunsen-burner & cubes of ice! thus&so: BP's and Waxman's cap&trade is striclty "free market;" let the arbitrageurs & daytrippers jack-up the price of energy, as much as they can, as with Waxman's '91 bill (presumably; there seems to be a dearth of "story" about how fantastic it was .-) thus&so: don't worry; British Petroleum's cap&trade & free beer/miles is on the way! thus&so: like, I typed, sea-ice is the most unstable thing -- aside from clouds. so, see Fred Singer's retrospective metastudy on world-around glaciers, Doofus. also, see the November '01 story in the Sunday LAtribcoTimes, "120 New Glaciers Found on Continental Divide." thus&so: what if El Nino is correlated with underwater vulcanism? I started looking at ENSO, just before it was called that. well, it was two things, El Nino and the Quasibiennial Southern Oscillation, the latter having had a period of about 26 months. so, now, draw some conclusion! > The global temperature lags ENSO by 6 months. thus&so: as in, Beyond Petroleum (tm) -- stuff that's squeezed from a holow rock, and is allegedly fossilized. in my experience, neither R or D know the definition of "republic," or much of the history of the idea. anyway, the whole problem of the Anthropocene was highlighted, perhaps for some purpose, by having the conference in the venue of the Copenhagenskool of QM thus&so: Myth 1 is supported by the old Shackleton et al study, which seems to show a spike in CO2, just before the glacial phase. Myth 2 is somewhat overstated, since the change in obliquity of Earth's orbit is synched -- not causative -- with the 100,000-year cycle of glaciation in the Quaternary. Myth 5 is supported by the fact that the floating-point spec is inherently chaotic (IEEE-755, -855, I think); think, "fractals are the very definition of psychedelia, man!" > * Myth 1 Ice core records show that changes in temperature drive > changes in carbon dioxide, and it is not carbon dioxide that is > driving the current warming. > * Myth 2 Solar activity is the main driver of climate change. > * Myth 5 Climate models are too complex and uncertain to provide > useful projections of climate change." > http://climateprogress.org/2008/03/18/hadley-center-to-delayers-denie... > ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/annual.land_ocean.90S.90N.... thus&so: what if the same guy who was the source d'Eaugate for Bernward at the Post, was also the Vice President, who purposely set his mattress on fire in the first tower (second was hit by a 757 filled with fuel for most of a transcontinental flight, minus the steering loop); and, so, how many mattresses'd he have'd to set, to make for a controlled demolition? well, some of us believe that he was not just the acting president -- especially since the impeachment of Bill C.. also, what in Heck is a one-ball centrifuge -- doesn't one need two, at the least, for balance? --BP's cap&trade + free beer/miles on your CO2 debits at ARCO! http://wlym.com |