Scientist predicts existence of new galaxy

If Galaxy X is actually discovered following the prediction, it could provide a whole new dimension to our current understanding of the Milky Way – a galaxy to which the Sun and the Earth belong to – and the esoteric “dark matter” which, though invisible to the naked eye, fills up most of the universe.

Buoyed by the strength of Sukanya Chakrabarti’s mathematical model, one astronomer has already applied for time on the Spitzer Space Telescope to look at infrared wavelengths for this hypothetical Galaxy X.

Chakrabarti – a theoretical astronomer at the University of California, Berkeley – presented her findings at a meeting of the American Astronomical Society in Seattle on Thursday. She used her method to correctly predict the mass and location of two dwarf satellite galaxies – M51 and NGC 1512. Both are of about one-hundredth, the size of the galaxy.

The technique works for satellite galaxies as small as one-thousandth the mass of the primary galaxy.

Chakrabarti used mathematical method to predict that a dwarf galaxy sits on the opposite side of the Milky Way from the Earth. It remains unseen because it is obscured by the intervening gas and dust in the galaxy’s disk.

Many large galaxies, such as the Milky Way, are thought to have lots of satellite galaxies too dim to see. They are dominated by “dark matter,” which astronomers say makes up 85 per cent of all matter in the universe but so far remains undetected. The Milky Way is surrounded by some 80 known or suspected dwarf galaxies that are called satellite galaxies.

Theoretical models of rotating spiral galaxies, however, predict there should be many more satellite galaxies, perhaps thousands, with small ones even more prevalent than large ones. Dwarf galaxies, however, are faint, and some of the galaxies may be primarily invisible dark matter.

“This approach has broad implications for many fields of physics and astronomy -- for the indirect detection of dark matter as well as dark-matter dominated dwarf galaxies, planetary dynamics, and for galaxy evolution driven by satellite impacts,” she said.

“The method is like inferring the size and speed of a ship by looking at its wake. You see the waves from a lot of boats, but you have to be able to separate out the wake of a medium or small ship from that of an ocean liner,” Chakrabarti’s colleague Leo Blitz, a UC Berkeley professor of astronomy, said.