Featured Research

from universities, journals, and other organizations

Large Area Telescope Explores High-energy Particles

Date:
July 28, 2009
Source:
Naval Research Laboratory
Summary:
NASA's Fermi Gamma-ray Space Telescope is making some exciting discoveries about cosmic rays and the Large Area Telescope aboard Fermi is the tool in this investigation.

NASA's Fermi Gamma-ray Space Telescope is making some exciting discoveries about cosmic rays and the Large Area Telescope aboard Fermi is the tool in this investigation. Scientists in the Naval Research Laboratory's (NRL's) Space Science Division were instrumental in the design and development of the Large Area Telescope (LAT).

Cosmic rays are electrons, positrons, and atomic nuclei that move at nearly the speed of light. Astronomers believe that the high-energy cosmic rays originate from exotic places in the galaxy, such as the debris of exploded stars.

The LAT is a wide field-of-view imaging telescope, which consists of a tracker that determines the trajectory of the gamma ray or cosmic ray being measured, and an NRL-developed cesium-iodide calorimeter that determines the energy of the incoming ray. A charged-particle anti-coincidence shield helps filter out unwanted signals, such as those produced by background particles. LAT was developed for detecting gamma rays; however, it is also proving to be a great tool for studying the high-energy electrons in cosmic rays.

Gamma rays travel in straight lines, so scientists are able to pinpoint their sources simply by measuring the direction of each gamma ray as it arrives at the LAT. In contrast, cosmic rays diffuse through our Galaxy, scattering off and spiraling through the turbulent galactic magnetic fields. Because of their movements, scientists find it challenging to determine where the cosmic rays originated. One of Fermi's main goals is determining the sources of cosmic rays.

NRL's highly sensitive LAT measured the energies of more than four million high-energy electrons between August 2008 and January 2009, far more high-energy electrons than have ever been studied before. This extremely large data set allowed scientists to make a precise census of high-energy electrons and led to a surprising excess in the rate of electrons striking the LAT, more than expected from earlier measurements and theoretical models. The LAT data appear to be key to understanding electron measurements made from the European satellite PAMELA and the ground-based High Energy Spectroscopic System located in Namibia.

The Fermi LAT's results indicate that our understanding of the sources and propagation of high-energy particles in the galaxy is incomplete, and they seem to suggest that there is a nearby object beaming cosmic rays in the direction of Earth. Some scientists suggest that a nearby pulsar – the fast-spinning leftover of an exploded star – could be the source sending the electrons and positrons toward Earth. A more exotic possibility is that the particles are evidence of the existence of dark matter. For some time, astrophysicists have suggested that some form of matter – previously undetected and invisible, hence "dark" – exists to provide the extra gravity needed to keep galaxies from whirling apart. While researchers have never directly and conclusively observed dark matter, it could be that the excess electrons LAT observes are the result of interactions or decays of the theorized dark matter particles. Looking ahead, Fermi researchers will be watching for changes in the cosmic ray activity in different parts of the sky. This activity might help them piece together the puzzle in finding the source for the cosmic rays.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership mission, developed in collaboration with the U.S. Department of Energy and contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.


Story Source:

The above story is based on materials provided by Naval Research Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Naval Research Laboratory. "Large Area Telescope Explores High-energy Particles." ScienceDaily. ScienceDaily, 28 July 2009. <www.sciencedaily.com/releases/2009/07/090728111407.htm>.
Naval Research Laboratory. (2009, July 28). Large Area Telescope Explores High-energy Particles. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2009/07/090728111407.htm
Naval Research Laboratory. "Large Area Telescope Explores High-energy Particles." ScienceDaily. www.sciencedaily.com/releases/2009/07/090728111407.htm (accessed July 28, 2014).

Share This




More Space & Time News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

This Week @ NASA, July 25, 2014

This Week @ NASA, July 25, 2014

NASA (July 25, 2014) Apollo 11 celebration, Next Giant Leap anticipation, ISS astronauts appear in the House and more... Video provided by NASA
Powered by NewsLook.com
Space to Ground: Coming and Going

Space to Ground: Coming and Going

NASA (July 25, 2014) One station cargo ship leaves, another arrives, aquatic research and commercial spinoffs. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
Powered by NewsLook.com
How A Solar Flare Could Have Wrecked Earth's Electronics

How A Solar Flare Could Have Wrecked Earth's Electronics

Newsy (July 25, 2014) Researchers say if Earth had been a week earlier in its orbit around the sun, it would have taken a direct hit from a 2012 coronal mass ejection. Video provided by Newsy
Powered by NewsLook.com
Raw: ISS Cargo Ship Launches in Kazakhstan

Raw: ISS Cargo Ship Launches in Kazakhstan

AP (July 23, 2014) The Progress 56 cargo ship launched from the Baikonur Cosmodrome in Kazakhstan Wednesday. NASA says it will deliver cargo and crew supplies to the International Space Station. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins