View Full Version : Possible Signal from Dark Matter

2014-Dec-12, 03:27 PM
From Laboratory Equipment magazine (http://www.laboratoryequipment.com/videos/2014/12/scientists-find-possible-signal-dark-matter?et_cid=4314476&et_rid=54636800&location=top)

Could there finally be tangible evidence for the existence of dark matter in the Universe? After sifting through reams of X-ray data, scientists in EPFL's Laboratory of Particle Physics and Cosmology (LPPC) and Leiden Univ. believe they may have identified the signal of a particle of dark matter. This substance, which up to now has been purely hypothetical, is run by none of the standard models of physics other than through the gravitational force. Their research will be published next week in Physical Review Letters.

Two groups have recently announced that they have detected the much sought after signal. One of them, led by EPFL scientists Oleg Ruchayskiy and Alexey Boyarsky, also a professor at Leiden Univ. in the Netherlands, found it by analyzing X-rays emitted by two celestial objects - the Perseus galaxy cluster and the Andromeda galaxy. After having collected thousands of signals from the ESA's XMM-Newton telescope and eliminated all those coming from known particles and atoms, they detected an anomaly that, even considering the possibility of instrument or measurement error, caught their attention.

The signal appears in the X-ray spectrum as a weak, atypical photon emission that could not be attributed to any known form of matter. Above all, "the signal's distribution within the galaxy corresponds exactly to what we were expecting with dark matter, that is, concentrated and intense in the center of objects and weaker and diffuse on the edges," explains Ruchayskiy. "With the goal of verifying our findings, we then looked at data from our own galaxy, the Milky Way, and made the same observations," says Boyarsky.

The signal comes from a very rare event in the Universe: a photon emitted due to the destruction of a hypothetical particle, possibly a "sterile neutrino." If the discovery is confirmed, it will open up new avenues of research in particle physics.

2014-Dec-12, 03:41 PM
I'll be curious to see if this is simply more about the 3.5 keV signal, or if it is something previously not reported.

2014-Dec-12, 10:33 PM
I'm admittedly a little confused. The article on space.com - http://www.space.com/27985-dark-matter-signal-sterile-neutrino.html refers to the February paper by Boyarski - http://arxiv.org/abs/1402.4119. I fail to see what is considered 'new' in this, and other similar articles issued on 12/11.

2014-Dec-13, 12:00 AM
If dark matter can emit photons (albeit so far only in X-rays) and thus be detectable will the phrase "dark matter" have to be replaced?

2014-Dec-13, 08:35 AM
There has been plenty of speculation about the 3.5keV source over the last couple of years, and I do not understand how anyone can possibly jump to the conclusion that this is a dark matter emitter. The simpliest explanation is that it is a highly redshifted feature emitted very near a black hole event horizon. Generally these lines should be highly blurred, but there are viewing angles that can constructively stack a spectral into a resonant sequence; and we should expect this type of phenomena near galactic centers.

If dark matter is omni present, and emits this type of signal, why do we not find this line in more sources? Perhaps we will, but again, accretion rings should be everywhere too; and I don't see an easy way to break the inherent degeneracy of gazing into the complex nucleus of galaxies and extracting new physics - (like it or not, dark matter emissions are new physics). This is too much like gazing into a crystal ball and seeing Aunt Emm in her kitchen.

2014-Dec-13, 01:33 PM
Ethan Siegel of Starts With A Bang (https://medium.com/starts-with-a-bang/ask-ethan-66-did-we-just-find-dark-matter-1b2f992ac353) wrote about it saying yes, they are talking about the 3.5 keV observations, and no it probably isn't dark matter.