A new radial acceleration relation found among spiral and irregular galaxies challenges current understanding – and possibly existence - of dark matter.
In the late 1970s, astronomers Vera Rubin and Albert Bosma independently found that spiral galaxies rotate at a nearly constant speed: the velocity of stars and gas inside a galaxy does not decrease with radius, as one would expect from Newton's laws and the distribution of visible matter, but remains approximately constant. Such 'flat rotation curves' are generally attributed to invisible, dark matter surrounding galaxies and providing additional gravitational attraction.
Now a team led by Case Western Reserve University...
With the new fall semester kicking off, we've just published the latest CWRU Astronomy newsletter. It features a Hubble Space Telescope study of the nearby spiral galaxy M101 by Chris Mihos and collaborators, a variety of new research databases created by CWRU astronomers, a feature of our historic 9.5" Warner and Swasey refractor, and more.
Watch for it coming soon to your mailbox, or download a copy here.
The new Spitzer Photometry and Accurate Rotation Curves (SPARC) database is publicly available online. Created by team leaders Federico Lelli and Stacy McGaugh (CWRU Astronomy) and Jim Schombert (UOregon Physics), SPARC is a sample of 175 disk galaxies covering a broad range of morphologies (S0 to Irr), luminosities (107 to 1012 Lsun), and sizes (0.3 to 15 kpc). For each galaxy, the team collected both HI data and Spitzer images at 3.6 um. The HI data provide the gas distribution and the galaxy rotation curve, tracing the total gravitational potential: these data are the fruits of 30 years of...
For years, the reigning model for cosmology argues that the universe is filled with unseen dark matter, believed to comprise the bulk of the mass in the universe. However, despite painstaking searches, scientists have yet to detect particles which would make up this dark matter. Why are these particles so elusive? Might they not be there at all? On the evening of June 2 at the World Science Festival in New York City, CWRU Astronomy chair Stacy McGaugh joined a panel of scientists to discuss alternative theories about the presence (or absence!) of dark matter in the universe. You...