Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA's Fermi Explores High-energy "Space Invaders"

06.05.2009
Since its launch last June, NASA's Fermi Gamma-ray Space Telescope has discovered a new class of pulsars, probed gamma-ray bursts and watched flaring jets in galaxies billions of light-years away. Today at the American Physical Society meeting in Denver, Colo., Fermi scientists revealed new details about high-energy particles implicated in a nearby cosmic mystery.

"Fermi's Large Area Telescope is a state-of-the-art gamma-ray detector, but it's also a terrific tool for investigating the high-energy electrons in cosmic rays," said Alexander Moiseev, who presented the findings. Moiseev is an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Cosmic rays are hyperfast electrons, positrons, and atomic nuclei moving at nearly the speed of light. Astronomers believe that the highest-energy cosmic rays arise from exotic places within our galaxy, such as the wreckage of exploded stars.

Fermi's Large Area Telescope (LAT) is exquisitely sensitive to electrons and their antimatter counterparts, positrons. Looking at the energies of 4.5 million high-energy particles that struck the detector between Aug. 4, 2008, and Jan. 31, 2009, the LAT team found evidence that both supplements and refutes other recent findings.

Compared to the number of cosmic rays at lower energies, more particles striking the LAT had energies greater than 100 billion electron volts (100 GeV) than expected based on previous experiments and traditional models. (Visible light has energies between two and three electron volts.) The observation has implications similar to complementary measurements from a European satellite named PAMELA and from the ground-based High Energy Stereoscopic System (H.E.S.S.), an array of telescopes located in Namibia that sees flashes of light as cosmic rays strike the upper atmosphere.

Last fall, a balloon-borne experiment named ATIC captured evidence for a dramatic spike in the number of cosmic rays at energies around 500 GeV. "Fermi would have seen this sharp feature if it was really there, but it didn't." said Luca Latronico, a team member at the National Institute of Nuclear Physics (INFN) in Pisa, Italy. "With the LAT's superior resolution and more than 100 times the number of electrons collected by balloon-borne experiments, we are seeing these cosmic rays with unprecedented accuracy."

Unlike gamma rays, which travel from their sources in straight lines, cosmic rays wend their way around the galaxy. They can ricochet off of galactic gas atoms or become whipped up and redirected by magnetic fields. These events randomize the particle paths and make it difficult to tell where they originated. In fact, determining cosmic-ray sources is one of Fermi's key goals.

What's most exciting about the Fermi, PAMELA, and H.E.S.S. data is that they may imply the presence of a nearby object that's beaming cosmic rays our way. "If these particles were emitted far away, they’d have lost a lot of their energy by the time they reached us," explained Luca Baldini, another Fermi collaborator at INFN.

If a nearby source is sending electrons and positrons toward us, the likely culprit is a pulsar -- the crushed, fast-spinning leftover of an exploded star. A more exotic possibility is on the table, too. The particles could arise from the annihilation of hypothetical particles that make-up so-called dark matter. This mysterious substance neither produces nor impedes light and reveals itself only by its gravitational effects.

"Fermi's next step is to look for changes in the cosmic-ray electron flux in different parts of the sky," Latronico said. "If there is a nearby source, that search will help us unravel where to begin looking for it."

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 important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.

Francis Reddy | EurekAlert!
Further information:
http://www.nasa.gov
http://www.nasa.gov/mission_pages/GLAST/news/space_invaders.html

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>