Hopes dim that gamma rays can reveal dark matter

This composite image shows the galaxy cluster 1E 0657-56, also known as the "bullet cluster", formed after the collision of two large clusters of galaxies. Hot gas detected by Chandra is seen as two pink clumps in the image and contains most of the "normal" matter in the two clusters. An optical image from Magellan and the Hubble Space Telescope shows galaxies in orange and white. The blue clumps show where most of the mass in the clusters is found, using a technique known as gravitational lensing. Most of the matter in the clusters (blue) is clearly separate from the normal matter (pink), giving direct evidence that nearly all of the matter in the clusters is dark. This result cannot be explained by modifying the laws of gravity.

An astronomical calling card, tentatively attributed to mysterious dark matter, appears prone to be because of an extramundane supply.

An unexplained glow of high-energy gentle from the middle of the Milky Manner, first noticed in 2009, raised scientists’ hopes of higher pinning down darkish matter (SN: 11/20/10, p. 11). That unidentified substance has been detected to date solely through its gravitational tug on the different matter.

Physicists thought that this extra of energetic gentle often known as gamma rays is likely to be launched by the annihilation of particles of darkish matter that mill in regards to the galaxy’s core (SN: 5/17/14, p. 8). However, an evaluation revealed August 6 in Nature Astronomy means that the sunshine isn’t from darkish matter in any case. As an alternative, the gamma rays are likely to spit out by different galactic denizens, similar to spinning lifeless stars referred to as pulsars which can be identified to provide the sunshine.

The scientists studied the distribution of the gamma rays to get a deal with on the sunshine’s origins. The darkish matter is assumed to shroud the Milky Manner in a featureless, spherical halo. However, stars throughout the galaxy are distributed otherwise, residing in a skinny disk with a bulge on the heart of the Milky Manner. The areas of the galaxy that the gamma rays are coming from a match up to higher with the distribution of stars than that of darkish matter, the researchers discovered.

Different current research has likewise raised doubt that the gamma rays are because of darkish matter (SN: 5/27/17, p. 15), casting a shadow on scientists’ vibrant hopes.