For a few years now, excess emission of gamma-rays in the direction of the Galactic Center has puzzled scientists. In the paper we discuss today, the authors re-analyze data from the Fermi telescope to get new insights into the origin of this excess emission. They make the case for the signal being described by dark matter particles annihilating in the center of our Galaxy.
In 2010 the Fermi-LAT reported a surprising discovery: detection of a gamma ray transient that appeared to come from a nova, V407 Cyg. Since V407 Cyg is a special type of nova, however, it was considered a one-off event. Now two other classical novae have also been found in gamma rays.
I’m going to go ahead and give away the punchline: the answer to this post’s title is, “If your source is within 8 degrees of the Moon, quite probably.” — at least according to this paper’s authors. Read on to find out why!
A flurry of recent papers point to detection of a ~130 GeV gamma-ray emission line from near the Galactic center. If real, this could be the first detection of a signature of annihilating dark matter.
Dark matter is not so dark as the name might imply. Although it so far refuses to interact with normal matter via any force other than gravity, there are secondary signals that we can detect. When we turn our gamma-ray telescopes on regions like the Galactic Center that contain a high density of dark matter, we expect to see a dim, widespread gamma ray haze coming from seemingly empty space, with no baryonic matter source. This paper, due to be published by the Astrophysical Journal, discusses the search for this signature by the collection of satellites that surrounds the Milky Way, and uses the lack of a detection to set an upper limit on the cross-section of the WIMP particle.
Conference proceedings from the 2011 Fermi Symposium highlight some of the major science applications of the gamma-ray space observatory.
The Fermi Large Area Telescope used a clever method of splitting electrons and positrons via the Earth’s magnetic field to show that there’s a significant excess of cosmic ray positrons at high energies – much more than can be explained using known cosmic ray processes.
The Crab Nebula has long been used as a standard candle in order to calibrate high-energy instruments … but it turns out it’s had us fooled all along! This paper gives an overview of what we’ve been missing from the Crab Nebula, and what this could mean for our understanding of high-energy astrophysics.