Mysterious phenomenon at the heart of the Milky Way could point to new dark matter suspect. 'We may have been overlooking its subtle chemical effects on the cosmos.'

Dark matter may affect gas ionization in the Milky Way's center, pointing to a new suspect lighter than usual.

: Research led by Shyam Balaji suggests that a new form of dark matter lighter than a proton could exist in the Milky Way's core. This dark matter is believed to self-annihilate, forming electrons and positrons, causing unexpected ionization in the Central Molecular Zone. Unlike axions, this dark matter may not show strong gravitational effects but impacts cosmic gas chemistry. Future work with NASA’s COSI telescope could clarify the link between dark matter and unusual emissions in this galactic core.

Scientists suggest that dark matter in the center of the Milky Way may be responsible for unexpected amounts of ionized gas, a finding that hints at a new particle lighter than a proton. Shyam Balaji, a Postdoctoral Research Fellow at King's College London, leads this research, proposing a new dark matter candidate that could self-annihilate to produce electron-positron pairs. These pairs, in turn, create the ionization observed in the Central Molecular Zone (CMZ), a region of dense cosmic gas.

Dark matter makes up about 85% of the universe's mass, yet remains invisible and only indirectly observable through its gravitational effects. Unlike ordinary baryonic matter, it doesn't interact with light. As such, the proposed dark matter form from Balaji and his team wouldn't be detected through traditional methods, such as gravitational lensing or light interaction, but through its chemical impact: stripping electrons from neutral atoms in the CMZ.

Balaji points out that this candidate could be unique due to its lighter mass, under one billion electronvolts (eV), and its ability to self-annihilate into electron-positron pairs, a process not common among other dark matter suspects like axions. While axions and related particles often come with gravitational clues, they usually do not engage in creating significant ionization signatures or producing electron-positron pairs at rates sufficient for the CMZ phenomenon.

The current challenge is obtaining more accurate measurements of CMZ ionization rate to establish a clearer connection to dark matter. The absence of significant gamma-ray emissions from the CMZ, a byproduct of cosmic ray ionization, adds weight to the theory that dark matter could be an alternative ionization source. Scientists remain hopeful that NASA’s upcoming Compton Spectrometer and Imager gamma-ray telescope (COSI), in 2027, could offer more definitive data to assess this claim.

This line of inquiry hopes not only to enlighten dark matter's properties but also to refine our methods for detecting it. Understanding dark matter's role through ionization processes could revolutionize studies, moving beyond gravitational focuses to explore how it shapes cosmic chemistry.

Sources: space.com, physical.org, NASA

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