Astronomers are left scratching their heads over a new observation of a “clump” of dark matter apparently left behind after a massive merger between galaxy clusters. What is so puzzling about the discovery is that the dark matter collected into a “dark core” which held far fewer galaxies than expected. The implications of this discovery present challenges to current understandings of how dark matter influences galaxies and galaxy clusters.
Initially, the observations made in 2007 were dismissed as bad data. New data obtained by the Hubble Space Telescope in 2008 confirmed the previous observations of dark matter and galaxies parting ways. The new evidence is based on observations of a distant merging galaxy cluster named Abell 520. At this point, astronomers have a challenge ahead of them in order to explain why dark matter isn’t behaving as expected.
This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters. Image Credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University)
NASA Chandra X-Ray Observatory blog – Looking back on the more than twelve years of science from NASA’s Chandra X-ray Observatory and trying to predict what it will find in the future, one thing is certain: we can expect the unexpected.
Expected and Detected:
X-ray emission was detected from the atmospheres of planets and comets. The X-rays are produced when solar X-rays and high-speed particles flowing away from the Sun hit these atmospheres. The observed X-radiation provides information on the outer atmospheres of these objects that is difficult to obtain with other telescopes.
Unexpected: The X-radiation from Jupiter’s aurora, the equivalent of Earth’s Northern Lights, was discovered to be located very near Jupiter’s poles, suggesting that the auroral X-rays are produced by particles streaming along Jupiter’s magnetic field all the way from Jupiter’s moon Io.
Unexpected: The strongest X-ray emission from Saturn came from its equatorial regions and varied with solar activity, suggesting that Saturn acts like a surprisingly efficient X-ray mirror that reflects X-rays from the Sun.
Nextbigfuture – The region of space behind a superluminally travelling warp bubble is almost entirely devoid of forward travelling particles, however it contains a sparse distribution of particles with greatly reduced energy. Meanwhile the region of space infront of a ship decelerating from superluminal velocity to subluminal velocity is blasted with a concentrated beam of extremely high energy particles. These results suggest that any ship using an Alcubierre warp drive carrying people would need shielding to protect them from potential dangerously blueshifted particles during the journey, and any people at the destination would be gamma ray and high energy particle blasted into oblivion due to the extreme blueshifts for P+ region particles.
Next Big Future has covered the Startram concept in detail before. The GEN 1 concept involves using long, evacuated tunnels to accelerate unmanned payloads to orbital velocity. In theory, this concept could bring launch costs to LEO down to $50 dollar per kilogram. A more ambitious GEN 1.5 system could would take longer and greater resources to develop but could also put humans into orbit for a similar per-kilogram cost. In an interview with Sander Olson, Startram visionary James Powell discusses why he believes that the concept is viable, and how it could be developed within twenty years for $40 billion.
Nextbigfuture – The near-Earth asteroid 2011 AG5 currently has an impact probability of 1 in 625 for Feb. 5, 2040, said Donald Yeomans, head of the Near-Earth Object Observations Program at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
Nextbigfuture – XCOR Aerospace announced today that it recently closed a $5 million round of equity funding. The round, combined with cash on hand plus anticipated and existing contracts, should fund the company through production of its Lynx Mark I Suborbital vehicle.