Another Unknown Force Acting on Dark Matter?

Scientists now believe that interactions between dark and ordinary matter is more important and complex than previously thought. For instance, dark matter 'knows' how the visible matter is distributed and they conspire with one another such hat gravity of visible matter at the characteristic radius of the dark halo is always the same. Therefore, it is possible that a non-gravitational fifth force is ruling dark matter, leaving the same mark on all galaxies irrespective of their ages, shapes and sizes. This might be an explanation for the mystery of 'dark energy'. This research is important to the theories that relate to the history and expansion of the universe.

If we account for our observations with a modified law of gravity, it makes perfect sense to replace the effective action of hypothetical dark matter with a force closely related to the distribution of visible matter.

Reference:

Gianfranco Gentile, Benoit Famaey, HongSheng Zhao, Paolo Salucci. Universality of galactic surface densities within one dark halo scale-length. Nature, 2009; 461 (7264): 627 DOI: 10.1038/nature08437

Dark Matter Bolometer Detector

The existence of dark matter is induced from the behavior of faraway galaxies, which move in ways that can only be explained by a gravitational pull caused by more mass than can be seen. They estimate dark matter represents around 20 percent of the universe, with the other 75 percent made up of dark energy, a repulsive force that is causing the universe to expand at an ever-quickening pace.

Eduardo Abancens designed a prototype dark matter detector called a scintillating bolometer. It is a crystal so pure that it can conduct the energy ostensibly generated when a particle of dark matter strikes the nucleus of one of its atoms.

To prevent interference by cosmic rays, the bolometer is shielded in lead and kept half a mile underground. The challenge is to freeze the device to near-absolute zero, the temperature at which all motion stops. At the edge of absolute zero, it will possible to measure expected changes of a few millionths of a degree Fahrenheit.

Reference: “A BGO scintillating bolometer as dark matter detector prototype.” By N. Coron, E. García, J. Gironnet, J. Leblanc, P. de Marcillac, M. Martínez, Y. Ortigoza, A. Ortiz de Solórzano, C. Pobes, J. Puimedón, T. Redon, M.L. Sarsa, L. Torres and J.A. Villar. Optical Materials, Vol. 31 Issue 10, August 2009.

The Fate of Our Galaxy During Collision

Will neighboring Galaxies one day tear apart the disk of the Milky Way? Researchers used new computer simulations that shows these collisions will “puff up” a galactic disk, particularly around the edges, and produce structures called stellar rings. Interestingly, all galaxies are embedded within massive and extended halos of dark matter, and the intersections of most large galaxies lie at the intersections of dark matter.

Reference: Science Daily