An upper limit to the central density of dark matter haloes
in [Physics]
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From: Sam Wormley on 23 Mar 2010 18:38 ScienceShot: Black Holes Tease Out a Dark Matter Secret Mysterious stuff may have a density limit http://news.sciencemag.org/sciencenow/2010/03/science-shot-black-holes-tease-o.html?etoc An upper limit to the central density of dark matter haloes from consistency with the presence of massive central black holes http://arxiv.org/abs/1002.0553 http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.0553v1.pdf We study the growth rates of massive black holes in the centres of galaxies from accretion of dark matter from their surrounding haloes. By considering only the accretion due to dark matter particles on orbits unbound to the central black hole, we obtain a firm lower limit to the resulting accretion rate. We find that a runaway accretion regime occurs on a timescale which depends on the three characteristic parameters of the problem: the initial mass of the black hole, and the volume density and velocity dispersion of the dark matter particles in its vicinity. An analytical treatment of the accretion rate yields results implying that for the largest black hole masses inferred from QSO studies ($>10^{9} M_{\odot}$), the runaway regime would be reached on time scales which are shorter than the lifetimes of the haloes in question for central dark matter densities in excess of $250 M_{\odot}$pc$^{-3}$. Since reaching runaway accretion would strongly distort the host dark matter halo, the inferences of QSO black holes in this mass range lead to an upper limit on the central dark matter densities of their host haloes of $\rho_{0} < 250 M_{\odot} $pc$^{-3}$. This limit scales inversely with the assumed central black hole mass. However, thinking of dark matter profiles as universal across galactic populations, as cosmological studies imply, we obtain a firm upper limit for the central density of dark matter in such structures.
From: Uncle Al on 23 Mar 2010 19:00 Sam Wormley wrote: [snip] > http://arxiv.org/abs/1002.0553 > http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.0553v1.pdf > > We study the growth rates of massive black holes in the centres of > galaxies from accretion of dark matter from their surrounding haloes. [snip] There is no dark matter nor is there anything of which is could be composed. There is only persistent defective theory and curve fitting. -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz4.htm
From: Sam Wormley on 23 Mar 2010 19:06 On 3/23/10 6:00 PM, Uncle Al wrote: > Sam Wormley wrote: > [snip] > >> http://arxiv.org/abs/1002.0553 >> http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.0553v1.pdf >> >> We study the growth rates of massive black holes in the centres of >> galaxies from accretion of dark matter from their surrounding haloes. > [snip] > > There is no dark matter nor is there anything of which is could be > composed. There is only persistent defective theory and curve > fitting. > An now an upper density limit with the "defective" theory. :-)
From: Mick on 23 Mar 2010 21:39 There is no dark side of the moon really, matter of fact it's all dark. "Uncle Al" <UncleAl0(a)hate.spam.net> wrote in message news:4BA947F0.2BCC3C2(a)hate.spam.net... > Sam Wormley wrote: > [snip] > >> http://arxiv.org/abs/1002.0553 >> http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.0553v1.pdf >> >> We study the growth rates of massive black holes in the centres of >> galaxies from accretion of dark matter from their surrounding haloes. > [snip] > > There is no dark matter nor is there anything of which is could be > composed. There is only persistent defective theory and curve > fitting. > > -- > Uncle Al > http://www.mazepath.com/uncleal/ > (Toxic URL! Unsafe for children and most mammals) > http://www.mazepath.com/uncleal/qz4.htm
From: oriel36 on 24 Mar 2010 00:53
On Mar 23, 11:38 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > ScienceShot: Black Holes Tease Out a Dark Matter Secret > Mysterious stuff may have a density limit Maybe it will eventually dawn on people who may care that it always amounts to the same thing whether you discuss the imaginary black hole (no circumference/no center) or 'big bang' thingie (no circumference/ no center) that it always returns to the same point of departure of the Ra/Dec framework,something which horrified the geocentric astronomers that they sought a better explanation for observations which led to the discovery of planetary dynamics by Copernicus - And wherever anyone would be, he would believe himself to be at the center.Therefore, merge these different imaginative pictures so that the center is the zenith and vice versa. Thereupon you will see-- through the intellect..that the world and its motion and shape cannot be apprehended. For [the world] will appear as a wheel in a wheel and a sphere in a sphere-- having its center and circumference nowhere. . . " Nicolas of Cusa ,15th century The real scandal is the loss of information contained in the 24 hour value for rotation as it contains the dimensions and shape of the Earth whereas your 'every-point-is-the-center' based on the circumpolar motion of the constellations loses it - http://www.youtube.com/watch?v=BYy0EQBnqHI The disintegration of Western civilization,its inability to no longer reason properly or to act out desperate speculative ideologies has its roots in 17th century empiricism where all these imaginative things such as black hole or dark matter exist only in the imagination of mathematicians,nothing more or less. |