Faint light in Hubble image helps astronomers map dark matter

Dec. 20 (UPI) -- Scientists have yet to directly detect dark matter, and they don't know what dark matter actually is. But dark matter's presence and influence is reflected in the patterns and movement of light.

Using data collected by NASA/ESA Hubble Space Telescope, astronomers have developed a new way to "see" dark matter via distant starlight.

"We have found that very faint light in galaxy clusters, the intracluster light, maps how dark matter is distributed," Mireia Montes, researcher at the University of New South Wales, said in a news release.

Intracluster light is the light produced by stars ripped from their homes by the gravity of nearby galaxies. According to Montes and her colleagues, once freed from the gravity of their home galaxy, the roaming stars congregate near concentrations of dark matter.

"These stars have an identical distribution to the dark matter, as far as our current technology allows us to study," said Montes.

Previously, astronomers have relied on gravitational lensing to map the universe's dark matter.

The gravitational pull of dark matter is believed to play a significant role in gravitational lensing, the bending of distant light around intermediary galaxies and galactic clusters. Astronomers analyzed patterns in the light warped by the lensing clusters to map the granular distribution of dark matter in each group of galaxies.

According to the new research, the use of intracluster light offers scientists a more accurate and efficient way to trace the granular distribution of dark matter.

The new findings -- published in the journal Monthly Notices of the Royal Astronomical Society -- suggest intracluster light could also be used to determine whether or not dark matter experiences self-interactions or is collision-less, as predicted by the most popular cosmological models.

"If dark matter is self-interacting we could detect this as tiny departures in the dark matter distribution compared to this very faint stellar glow," said Ignacio Trujillo, researcher at the Institute of Astrophysics of the Canary Islands.

Montes and Trujillo hope to continue using their method to analyze the intracluster light in additional galaxy clusters -- and to compare their findings against the predictions of other dark matter mapping models.

"There are exciting possibilities that we should be able to probe in the upcoming years by studying hundreds of galaxy clusters," said Trujillo.