Skip to main content

A DARK MATTER HALO AS SOURCE OF GAMMA-RAYS?

Image: Illustration of a dark matter halo around the Milky Way. Credit: ESO/L. Calçada.


The gamma-ray source 3FGL J2212.5+0703 shows evidence of being spatially extended.

In a recent paper (Bertoni et al. 2016) the authors use a large sample of active galactic nuclei and other known gamma-rays sources as a control group, confirming, as expected, that statistically significant extension is rare among such objects.

They argue that the most likely (non-dark matter) explanation for this apparent extension is a pair of bright gamma-ray sources that serendipitously lie very close to each other, and estimate that there is a chance probability of ~2% that such a pair would exist somewhere on the sky.

If a gamma-ray source without detectable emission at other wavelengths were unambiguously determined to be spatially extended, it could not be explained by known astrophysics, and would constitute a smoking gun for dark matter particles annihilating in a nearby subhalo.

The authors assess that if 3FGL J2212.5+0703 is a dark matter subhalo, it would imply that dark matter particles have a mass of ∼18-33 GeV and an annihilation cross section on the order of σv ∼ 10−26 cm3/s, similar to the values required to generate the Galactic Center gamma-ray excess.

Although the information available does not allow to determine the mass of or distance to this subhalo, simulations suggest that the first gamma-ray detected subhalos could plausibly be on the scale of an ultra-faint dwarf galaxy located at a distance of ~10 kpc, or a much smaller clump of dark matter residing within a few tens of parsecs of the Solar System.


  • Bertoni et al. 2016 - Is The Gamma-Ray Source 3FGL J2212.5+0703 A Dark Matter Subhalo? (arXiv)
Etichette:

Comments

Post a Comment

Popular posts from this blog

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).
Post a Comment
Read more

A Sapphire Super-Earth

Twenty-one light years away, in the constellation Cassiopeia, a planet by the name of HD219134 b orbits its star with a year that is just three days long. With a mass almost five times that of Earth, it is what is known as a super-Earth. Unlike our planet, however, these super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminum and their oxides – including sapphire and ruby. HD219134 b is one of three candidates likely to belong to a new, exotic class of exoplanets. These objects are completely different from the majority of Earth-like planets. They have 10 to 20 percent lower densities than Earth. Researchers looked at different scenarios to explain the observed densities. For example, a thick atmosphere could lead to a lower overall density. But two of the exoplanets studied, 55 Cancri e and WASP-47 e, orbit their star so closely that their surface temperature is almost 3,000 degrees and they would have lost this ...
Post a Comment
Read more

CONTAMINATION BY SUPERNOVAE IN GLOBULAR CLUSTERS

Credit: ALMA (ESO/NAOJ/NRAO)/Alexandra Angelich (NRAO/AUI/NSF) Only a small amount of the supernovae products remains trapped within globular clusters and this "catch" only occurs in the most massive cases (mass cluster ≥ 10^6 solar masses).
Post a Comment
Read more