US scientist discovers new 'Galacto-Seismic' method to search for cosmic dark matter

By @Guneet_B on
Dark matter
This undated image from the Hubble Space Telescope shows a ghostly ring of dark matter in a galaxy cluster designated Cl 0024+17. Syfy airs a TV series titled "Dark Matter" which stars Mishka Thébaud as Adrian Maro, Melissa O'Neil as Two/Rebecca/Portia Lin and Zoie Palmer as The Android. Reuters/NASA, ESA, M.J. Jee and H. Ford/Johns Hopkins University/Handout

For a number of years, researchers from around the world have been trying to figure out ways to hunt for cosmic dark matter. The latest study conducted by an Indo-American researcher suggests that the secret to finding dark matter in the Milky Way and beyond could lie in the galaxy quakes or ripples.

The new field of galactoseismology pioneered by former UC Berkeley postdoctoral fellow Sukanya Chakrabarti probed the ripples in the distribution of the hydrogen gas in the Milky Way to hunt for the presence of invisible satellite galaxies, which are primarily dominated by dark matter. These ripples are believed to be caused by seismic-like waves, similar to a huge quake.

The researchers believe that thousands of such invisible satellite galaxies might be present in and around the Milky Way. For the first time in history, Chakrabarti used the new "Galacto-Seismic" method to study the galaxies’ mass and interior structure.

During the study, Chakrabarti and her team decided to look at the impact of the invisible satellite galaxies on the gas distribution in the Milky Way galaxy. According to UC Berkeley, the team used spectroscopic observations to calculate the speed of a trio of three brightly pulsating stars at the edge of the Milky Way in the Norma constellation. The three Cepheid variables are known to be drifting away from the galaxy.

The team used the Cepheid variables to identify and mark the location of a dwarf galaxy dominated by dark matter. The dwarf galaxy is believed to be located 300,000 light years away, and the disc of the Milky Way ends at about 48,000 light years.

The research team found that the Cepheids are drifting apart at a speed of 450,000 miles per hour. Meanwhile, the radial velocity of the stars in the stellar disk of the Milky Way is around 13,000 miles per hour.

"The radial velocity of the Cepheid variables is the last piece of evidence that we've been looking for," said Chakrabarti, in a press statement. "You can immediately conclude that they are not part of our Galaxy."

The complete details of the study have been published in Astrophysical Journal Letters.