* Astronomy

Blobrana · L

RE: Dark matter

Blobrana · L

Detector has an ear for dark matter
A slight difference in the sounds created by neutrons and alpha particles as they travel through a liquid could lead to the first direct detection of dark matter, say physicists working on the PICASSO experiment at SNOLAB in Canada.

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A team of researchers in Canada have made a bold stride in the struggle to detect dark matter. The PICASSO collaboration has documented the discovery of a significant difference between the acoustic signals induced by neutrons and alpha particles in a detector based on superheated liquids.
Since neutron induced signals are very similar to dark matter induced signals, this new discovery, published today, Thursday, 16 October, in the New Journal of Physics, could lead to improved background suppression in dark matter searches with this type of detector.
So far, alpha particles have been an obstacle to the detection of dark matter's weakly interacting massive particles (WIMPs) in PICASSO. This detector, which is based on the operation principle of the classic bubble chamber, is sensitive to alpha particles over exactly the same temperature and energy range, therefore making it very difficult to discriminate between the two types of particles.

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Title: Dark Matter signals from Draco and Willman 1: Prospects for MAGIC II and CTA
Authors: Torsten Bringmann, Michele Doro, Mattia Fornasa
(Version v2)

The next generation of ground-based Imaging Air Cherenkov Telescopes (IACTs) will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such a study, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably boost, in some cases, the gamma-ray flux at the high energies where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect unless one adopts rather (though by no means overly) optimistic astrophysical assumptions about the distribution of dark matter in the dwarfs.

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Blobrana · L

Stars at the centre of the Milky Way could gobble up enough dark matter to extend their lifetimes by a billion or more years, a new study suggests. If such stars are found, they could help reveal what the mysterious dark matter is actually made of.
Although it constitutes roughly 90% of the Milky Way's mass, dark matter is thought to be too diffuse in most parts of the galaxy to have a large effect on stars. But close to the colossal black hole at the galactic centre, the material might be sufficiently dense that stars can capture it at high rates.

Source

Blobrana · L

Scientists have discovered a surge of high-energy particles from the heart of the Milky Way, Earth's home galaxy, which closely matches the radiation signature predicted for dark matter. Details of the particles, detected by a European space probe, emerged at a cosmology conference in Stockholm.

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Blobrana · L

New observations from the 40-inch Wise Observatory telescope in Israel has revealed more than a dozen galaxies lined up along a bridge of dark matter inside a region of nearly empty space, which is being called as bridge to nowhere by astronomers.

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Credit J. Read & O. Agertz

A composite image of the dark matter disk (red contours) and the Atlas image mosaic of the Milky Way obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Centre/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

Blobrana · L

A DARK MATTER DISK IN OUR GALAXY
An international team of scientists predict that our Galaxy, the Milky Way, contains a disk of dark matter. In a paper published in Monthly Notices of the Royal Astronomical Society, astronomers Dr Justin Read, Professor George Lake and Oscar Agertz of the University of Zurich, and Dr Victor Debattista of the University of Central Lancashire use the results of a supercomputer simulation to deduce the presence of this disk. They explain how it could allow physicists to directly detect and identify the nature of dark matter for the first time.

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Blobrana · L

Title: Dark Matter signals from Draco and Willman 1: Prospects for MAGIC II and CTA
Authors: Torsten Bringmann, Michele Doro, Mattia Fornasa

The next generation of ground-based Imaging Air Cherenkov Telescopes (IACTs) will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such a study, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably boost, in some cases, the gamma-ray flux at the high energies where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect unless one adopts rather (though by no means overly) optimistic astrophysical assumptions about the distribution of dark matter in the dwarfs.

Read more (50kb, PDF)