Blade Posted July 27, 2008 Posted July 27, 2008 Dous the hypothesis of "every galaxy got it's own black hole" cancel out he hypothesis of there is mass missing so there is dark matter? Or can they coexist?
insane_alien Posted July 28, 2008 Posted July 28, 2008 they are not mutually exclusive. Supermassive blackholes at the center of galaxies is fact not hypothesis. IIRC we have yet to find a galaxy without one. Missing mass is also fact as this is observed. Dark matter is just used as a placeholder for whatever it is that makes up the extra mass. it may even turn out to not be matter.
DrP Posted July 28, 2008 Posted July 28, 2008 Did the discovery of the super massive black holes account for any of the missing mass? How much?
insane_alien Posted July 28, 2008 Posted July 28, 2008 i think the missing mass discovery came after the supermassive blackhole discovery. so eh none.
Klaynos Posted July 28, 2008 Posted July 28, 2008 i think the missing mass discovery came after the supermassive blackhole discovery. so eh none. This is my understanding of the timeline as well.
DrP Posted July 28, 2008 Posted July 28, 2008 I thought super massive black holes were quite a recent discovery - like in the 90's or something. First I ever heard of them was on a Horizon program sometime arround 2000 - 2003. How do we find out exactly when they were discovered?
Arch2008 Posted July 28, 2008 Posted July 28, 2008 The Wilkinson Microwave Anisotropy Probe (WMAP) shed some light on dark matter. Apparently it was here right from the beginning of the universe. Some candidates for DM are MACHOS (MAssive Compact HalO objectS) and WIMPS (Weakly Interactive Massive ParticleS). MACHOS are described as brown dwarf stars or minor black holes in the halo of a galaxy, whereas WIMPS are simply nuclear particles that interact weakly with the electromagnetic force, so they can essentially float right through your molecules and do not reflect light, etc. Since there were no stars at the beginning of the universe, I think that WIMPS are the most likely candidate. The DM was unaffected by the energy of the early universe. Enormous clouds of DM started collapsing while the ordinary matter was still too energized to form atoms. At about 380,000 years after the Big Bang, the universe cooled and atoms of hydrogen, helium and a dash of lithium formed. The gravity of the DM clouds caused these atoms to collapse and form the first stars and galaxies. Thus the supermassive black holes formed because of the DM. http://map.gsfc.nasa.gov/news/
Klaynos Posted July 28, 2008 Posted July 28, 2008 I thought super massive black holes were quite a recent discovery - like in the 90's or something. First I ever heard of them was on a Horizon program sometime arround 2000 - 2003. How do we find out exactly when they were discovered? We go to wikipedia... And we say about 1993... Dark energy: 1975 ish... So dark energy was much earlier... interesting... Most of the dark matter is outside the centre of the galaxy.
DrP Posted July 28, 2008 Posted July 28, 2008 (edited) It looks as though the conection between SMBH's and galaxy formation was put forward in June 2000. This is what the Horison program was going on about. Not sure about the actual SMBS discovery though. WIMPS and MACHOS -- Always thought that was funny!... Most of the dark matter is outside the centre of the galaxy. Then the discovery of SMBHs would make no difference to the theories on dark matter then, as the SMBHs are at the centre of galaxies right? Edited July 28, 2008 by DrP
Klaynos Posted July 28, 2008 Posted July 28, 2008 Then the discovery of SMBHs would make no difference to the theories on dark matter then, as the SMBHs are at the centre of galaxies right? Yes, it might make some difference I suppose as some of the dark matter is near the centre, but not much/enough :s
Blade Posted July 28, 2008 Author Posted July 28, 2008 The Variable gravity hypothesis and the super massive black hole hypothesis can help each other with the missing mass hypothesis.
Blade Posted July 28, 2008 Author Posted July 28, 2008 What do you mean by variable gravity, MOND? http://www.newscientist.com/article/mg12917624.400-science-variable-gravity-could-solve-cosmological-problems.html
Klaynos Posted July 28, 2008 Posted July 28, 2008 Got any proper papers on it? That's 17 years old, with a paper I could look for modern citations... If it had made big inbounds I'd ahve expected to read something about it...
Blade Posted July 28, 2008 Author Posted July 28, 2008 can't find anything recent on it. http://prola.aps.org/abstract/PRL/v67/i3/p298_1
Klaynos Posted July 28, 2008 Posted July 28, 2008 My online access only goes to 2001... But the joys of google scholar 15 citations... http://scholar.google.co.uk/scholar?hl=en&lr=&client=firefox-a&cites=3551569314637459921 http://www.iop.org/EJ/abstract/0034-4885/60/2/001 looks like it might be a good place to look... Which I do have access too Well after trying to grab it as I'm currently between courses my library account is in a semi-locked stage... so I can log in but can't actually do anything useful!
Arch2008 Posted July 29, 2008 Posted July 29, 2008 The WMAP data indicate the existence of Dark Matter right from the beginning of the universe. This pretty much pulls the rug out from under VG or MOND. Neutrinos were also found to have a miniscule mass.
Blade Posted July 29, 2008 Author Posted July 29, 2008 The WMAP data indicate the existence of Dark Matter right from the beginning of the universe. This pretty much pulls the rug out from under VG or MOND. Neutrinos were also found to have a miniscule mass. what/where dous MOND stand for?
Klaynos Posted July 29, 2008 Posted July 29, 2008 I knew that MOND was pretty much dead in the water, and that neutrino mass just wasn't high enough... but VG is not something I'd come across, thanks for that comment Arch2008.
Arch2008 Posted July 29, 2008 Posted July 29, 2008 (edited) MOdified Newtonian Dynamics-MOND http://en.wikipedia.org/wiki/Modified_Newtonian_dynamics My pleasure, Klaynos. I had a link to one of the members of the WMAP team where he explained this. I'll see if I can find it. Edited July 29, 2008 by Arch2008
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