Are primordial black holes made of dark matter?

NASA's Kepler satellite may provide the answer to the question of "Are primordial black holes made of dark matter?"

(PhysOrg.com) -- The primary objective of NASA’s Kepler satellite, which was launched in March 2009 to orbit the Sun, is to search for Earth-like planets in a portion of the Milky Way galaxy. But now a team of physicists has proposed that Kepler could have a second appealing purpose: to either detect or rule out primordial black holes (PBHs) of a certain mass range as the primary constituent of dark matter.

The scientists, Kim Griest and Agnieszka Cieplak of the University of California, San Diego; Bhuvnesh Jain of the University of Pennsylvania; and Matthew Lehner of the University of Pennsylvania and Academia Sinica in Taipei, Taiwan, have published their study on using the Kepler satellite to detect PBH dark matter in a recent issue of Physical Review Letters.

“The nature of the dark matter is one of the biggest unsolved problems in all of science and so an answer would be extraordinary,” Griest told PhysOrg.com. “If it turns out to be primordial black holes, that will be totally fascinating and everyone will want to understand what happened in the early universe to create them. If nothing is found, then we eliminate much of a major contender, but it is not as exciting.”

As the scientists explain, PBHs have been considered as a candidate for dark matter since the 1970s. These black holes are thought to have formed during the early universe from density perturbations that may have resulted from a variety of factors, such as inflation, phase transitions, and possibly even the collapse of string loops. Because there is no single theory for how PBHs formed, scientists don’t know how massive they would be. However, previous experimental and theoretical work has eliminated most PBH masses, including almost the entire mass range from 10-18 to 1016 solar masses, the exception being the mass range between 10-13 and 10-7 solar masses. Scientists call these 5 orders of magnitude the “PBH dark matter window.” Keep on reading...