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View Full Version : Milky Way Reveals 'Dark Accelerators"



kg034
2005-Mar-31, 09:05 AM
From here (http://www.spacedaily.com/news/gamma-05c.html):


In the March 25th 2005 issue of Science Magazine, the High Energy Stereoscopic System (H.E.S.S.) team of international astrophysicists, including UK astronomers from the University of Durham, report results of a first sensitive survey of the central part of our galaxy in very high energy (VHE) gamma-rays.

Included among the new objects discovered are two 'dark accelerators' - mysterious objects that are emitting energetic particles, yet apparently have no optical or x-ray counterpart.

um3k
2005-Mar-31, 04:15 PM
Does that mean that they are really, really, really hot?

Ilya
2005-Mar-31, 05:19 PM
Does that mean that they are really, really, really hot?

No. The hotter an object is, the shorter is the wavelength of its emission peak, but it also emits more electromagnetic radiation at ALL wavelengths. IOW, a 20,000 K temperature star looks blue because it emits a lot more blue light than red, but it still emits more red light than a 3,000 K star. A million-degree neutron star emits mostly in X-rays, but stll emits more blue light -- and red, -- than 20,000 K star (and is VERY bright to a human eye). So no, a "really, really, really hot" object would not be dark at all.

John Kierein
2005-Mar-31, 06:16 PM
This gives pictures. http://www.pparc.ac.uk/Nw/8sources.asp

I think I gleaned the energy range is TEV?

Maybe a source of antimatter annihilation for heavy atoms??

W.F. Tomba
2005-Mar-31, 06:34 PM
I think they're getting sloppy with the use of the "dark" terminology. Dark matter is dark because it emits no radiation at all. These things emit plenty of radiation, it's just confined to a particular band.

eburacum45
2005-Mar-31, 07:18 PM
Some things I have read suggest this stuff is coming from the self-annihilation of dark matter, some types of which may be their own anti-particle;
from here
http://www.cerncourier.com/main/article/45/1/22


The Galactic Centre has long been predicted as a source of VHE gamma rays generated in the accumulation and annihilation of dark-matter particles, for example the lightest stable supersymmetric particles. The characteristics of the gamma-ray signal detected by HESS are indeed consistent with the expected features for dark-matter annihilation, but would require very heavy (> 10 TeV) dark-matter particles and a large annihilation rate or enhanced density of the dark matter at the Galactic Centre