Cosmic filaments help set first limits on dark matter's decay into gravitons

Dark matter, which makes up roughly 85% of the universe's mass, reveals its existence only through gravity. Researchers from New York University, led by David Dunsky, have proposed a novel method to search for dark matter particles that might annihilate into gravitons, particles thought to transmit gravity itself. Their strategy entails observing the gravitational influence of dark matter on visible matter and measuring the faint gamma-ray photons that could be produced if dark matter decayed into gravitons through the Gertsenshtein effect.

This effect suggests that gravitons could convert into photons under the influence of magnetic fields, specifically in cosmic filaments, the vast, thread-like structures connecting galaxies. Since the decay of dark matter into gravitons, if it occurs, would primarily occur along these filaments, the researchers compared their predictions to the gamma-ray background measurements from the Fermi-LAT space telescope.

The lack of any unexpected excess allowed them to establish the first constraints on how rapidly dark matter could decay into gravitons over a wide range of particle masses. Importantly, this method relies solely on established physics and does not necessitate any additional theoretical frameworks. The team anticipates that future space telescopes, like the Advanced Particle-astrophysics Telescope, could enhance these constraints by up to ten times.

If dark matter does indeed decay into gravitons, this filament-scanning technique could become the most effective means of detecting the faint signal it would leave behind.