Cosmic Ray Hotspots Identified by Los Alamos
Cosmic rays have long been somewhat of a mystery to scientists. These high energy/high velocity particles are thought to originate from a variety of sources: from process within the Sun for the lowest energy variety all the way up to rotating neutron stars, supernovae, and black holes for the highest energy particles. Since July 2000 the Milagro cosmic ray observatory has been recording cosmic ray collision events in our atmosphere, allowing it to catalog around 200 billion of these events.
Most people have expressed the belief that cosmic ray events should be distributed evenly around the Earth, due to the proposed existence of cosmic ray generators throughout the galaxy and universe, which should also be positioned more or less evenly throughout. However, the analysis of the Milagro data over the past 8 years has led to the conclusion that cosmic ray distribution is uneven, heavily favoring specific regions of the sky near constellation Orion.
Because the particles that make up cosmic rays (protons, alpha particles, and electrons) are charged, though, they are heavily guided by any magnetic fields encountered. For this reason, it is hard to tell the exact origin.
It is kind of odd, though, that they didn’t mention exactly what energy classes of particles were examined. Cosmic rays are divided into classes based on energy, which can be a clue as to it’s origin - lower energy cosmic rays most likely come from within our galaxy, while higher energy cosmic rays most likely come from regions outside our galaxy.
“Our observatory is unique in that we can detect events of low enough energies that we were able to record enough cosmic-ray encounters to see a statistically significant fractional excess coming from two distinct regions of the sky,” said Brenda Dingus.
This could mean that all energies of cosmic rays were examined, and these statistical peaks observed near Orion are of galactic origin. John Pretz goes one further and suggests that these particles may be originating in close proximity to our solar system. Assuming they have excluded solar cosmic rays from the sun, then perhaps they are observing Anomalous Cosmic Rays (ACRs). Lower energy cosmic rays are defined as ACRs, and are thought to originate at the Heliosheath at the edge of our solar system.
Once I get my VPN access working again, I am going to read their paper, submitted to Physical Review Letters. The abstract is listed in the sources.
Sources:
Physorg
Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
This entry was posted on Thursday, November 27th, 2008 at 11:40 pm and is filed under Astrophysics, High Energy. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
