(ORDO NEWS) — An international team of researchers has concluded that a small dwarf satellite galaxy of the Milky Way may be responsible for the region of gamma rays visible at the center of our galaxy.
At the center of the Milky Way are 2 huge bubbles of gamma rays spanning 50,000 light-years across. They were discovered using the Fermi gamma-ray space telescope about 10 years ago. The source of this hourglass-shaped phenomenon remains unclear.
These Fermi Bubbles are dotted with several mysterious substructures with very bright gamma rays. One of the brightest spots, called the Fermi cocoon, is in the southern bubble. It was originally thought to be related to past outbursts from the galaxy’s supermassive black hole.
An international team of researchers analyzed data from the GAIA and Fermi space telescopes, which showed that the Fermi cocoon was actually formed by radiation from the Sagittarius dwarf galaxy.
Given that Sagittarius was at rest, only a few reasons for its gamma radiation have been identified:
1) A population of unknown millisecond pulsars.
2) Annihilation of dark matter.
Pulsars are rapidly rotating neutron stars that are the remnants of more massive stars. Possessing a strong magnetic field, they emit powerful streams of particles and radiation, including in the X-ray and gamma ranges.
Scientists in their study demonstrated that the gamma-ray cocoon can be explained by millisecond pulsars, and refuted the explanation of dark matter.
Their discovery identifies millisecond pulsars as efficient accelerators of high-energy electrons and positrons, and also suggests that similar physical processes may occur in other dwarf satellite galaxies of the Milky Way.
“This is important because dark matter researchers have long believed that the observation of gamma rays from a dwarf satellite is irrefutable evidence of dark matter annihilation.
Our study forces us to reconsider the potential for high-energy emission from stationary stellar objects such as dwarf spheroidal galaxies and their role as prime targets for dark matter annihilation searches,” the scientists said.
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