Dark matter filament found, scientists say

Granny wantin' to know how dey can see it if it's dark?...
:eusa_eh:
Fermi telescope may change to dark matter hunting
18 January 2013 - The Universe's highest-energy light could finally yield clues to the nature of the "dark matter" that makes up some 85% of the Universe's mass.
The Fermi space telescope, designed to catch gamma rays, has seen hints of evidence for dark matter in high-energy gamma rays seen at the galaxy's centre. The Fermi team is now opening a call for ideas on changing how it observes. That may focus efforts on those early hints, opening the possibility to solve one of physics' greatest mysteries. We only know of the existence of dark matter because of its gravitational effects; true to its name, it cannot be seen because it interacts only very weakly with light or normal matter. Proving its existence, and learning something about what it is, has been a holy grail for astrophysicists since the 1930s.

Julie McEnery, project scientist for the Fermi mission, said a deepening dark matter mystery has sparked the call for proposals to change the telescope's mission. "Some of the motivation to explore different observation strategies is from this tentative signal at the centre of the galaxy, but I think even if that wasn't there we would want to go to our community of scientists and ask them, 'based on what you've seen in the data, should we do something different?'," she told the BBC World Service programme Science in Action.

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The full sky is seen in the Fermi telescope map; gamma-ray sources abound along the central, galactic plane

Fermi has been a tremendous success at examining some of the most high-energy processes in the cosmos, publishing a catalogue filled with details of the spinning neutron stars known as pulsars, and a wide array of "active galactic nuclei" - probably supermassive black holes. But outside the Fermi team, the focus shifted in early 2012, when a pair of papers on the Arxiv preprint server suggested hints of dark matter within Fermi's data, which are publicly available.

The most popular theory holds that dark matter is made up of relatively heavy particles which, when they encounter one another, "annihilate" with a flash of light that the Fermi telescope can see. "The nice fact which distinguishes this situation from other similar situations with dark matter candidates is that there are no viable astrophysical alternatives," said Lars Bergstrom, who first proposed this idea in a paper in Physical Review D in 1988. "It is a so-called 'smoking gun' signal of dark matter annihilation," Prof Bergstrom told the BBC.

'Bump hunting'
 
Granny says dey oughta use dem gamma rays to zap dem jihadi terrorists inna butt...
:badgrin:
Excessive Gamma Rays at Milky Way’s Center Hint at Dark Matter
April 4th, 2014: Scientists believe high-energy gamma rays emanating from the center of our Milky Way are being produced by dark matter, the mysterious hypothetical substance believed to make up most of the physical universe.
A new study based on independent research of gamma ray light shows that the center of our galaxy is cranking out huge amounts of these light emissions. Gamma ray emissions are thought to be normally produced by sources such as interacting binary star systems (solar systems with two stars), isolated pulsars (rotating neutron stars), remnants of supernovae (exploding stars) and particles colliding with interstellar gas. However, scientists have deduced other sources must be contributing to the massive output.

The researchers involved with the study, including scientists from NASA and Stanford and Harvard universities, believe this excess gamma radiation could be produced by dark matter. “The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it,” said Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study. “The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models.”

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A map of gamma rays detected in the galactic center by the Fermi Space Telescope. Red indicates the greatest number emissions. Prominent pulsars are labeled (left). Removing all known gamma-ray sources (right) reveals excess emission that may arise from dark matter annihilations.

The scientists subtracted already known gamma ray sources from the amount of the high energy radiation coming out of the galactic center and found a remaining patch of leftover emissions. “This study is an example of innovative techniques applied to Fermi data by the science community,” said Peter Michelson, a Stanford University physics professor and the principal investigator for the Large Area Telescope (LAT), the principal scientific instrument on the Fermi Gamma Ray Space Telescope spacecraft. “The Fermi LAT Collaboration continues to examine the extraordinarily complex central region of the galaxy, but until this study is complete we can neither confirm nor refute this interesting analysis.”

While dark matter provides a convenient explanation for the gamma ray excess, the researchers point out it will take further investigation to confirm the role dark matter plays in the production of the excess gamma radiation. They also note continued research could reveal other possible alternative sources of the gamma rays that do not require dark matter.

Excessive Gamma Rays at Milky Way?s Center Hint at Dark Matter « Science World
 

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