Dr. Doug Clowe
Dr. Douglas Clowe, Associate Professor of Physics & Astronomy, was quoted about his research in an article headlined “Dark Matter Invisibility” in the News Blaze.
Dark matter has not been explained by modern physics – yet. Researchers know dark matter exists because it bends light from distant galaxies and changes galaxies’ rotations. Most scientists believe it’s composed of yet-to-be-discovered particles which almost never interact other than through gravity, making it difficult for detection….
Douglas Clowe of Ohio University, is reporting on new Hubble observations not finding a dense clump of dark matter in the universe. “The region of interest lies at the center of a collision among massive galaxy clusters in Abell 520, located 2.4 billion light-years away,” Clowe said. “Our measurements are in complete agreement with how we would expect dark matter to behave.” Because dark matter is not visible, its presence is only found by its gravitational effects on other bodies.
Hubble has now revealed the monster “El Gordo” galaxy above is really, really huge. “El Gordo” [Spanish – “the fat one”] refers to a monstrous cluster of galaxies when the universe was just half of its current age of 13.8 billion years. It contains several hundred galaxies swarming around under a collective gravitational pull. The total mass of the cluster, is estimated to be as much as 3 million-billion stars. Actually 3,000 times larger than the Milky Way, the mass is hidden as dark matter. The cluster is huge because of a titanic collision between two galaxy clusters.
A fraction of this mass is locked up in several hundred galaxies inhabiting the cluster. The rest is tied up in dark matter, making up most of the universe. Nothing like this has ever been seen to exist so far back in time, when the universe was roughly half of its current age. The immense size of ˆ was first known in 2012. They were able to put together estimates of the cluster’s mass based on motions of the galaxies internal to the cluster.
The expectation of “unaccounted energy” comes from the merger occurring tangentially to the observers’ line of sight. This means they are potentially missing a good fraction of the kinetic energy because their measurements only track the radial speeds of the galaxies.
Hubble’s high resolution allowed measurements of so-called “weak lensing,” where the cluster’s immense gravity warps images of background galaxies. The greater the warping, the more mass is locked up in the cluster.
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