Subscribe free to our newsletters via your
. 24/7 Space News .




Subscribe free to our newsletters via your




















STELLAR CHEMISTRY
Fermi Satellite Observes Billionth Gamma Ray with LAT Instrument
by Staff Writers
Menlo Park, CA (SPX) May 15, 2017


The sky in gamma rays. Drag the handle to compare the all-sky maps of the LAT instrument (left) on the Fermi Gamma-ray Space Telescope and the previous-generation EGRET instrument (right) on the Compton Gamma-ray Observatory. The LAT data reveal much more detail. (NASA)

Imagine you had superhero vision and could see a whole new world of fascinating phenomena invisible to the human eye. NASA's Fermi Gamma-ray Space Telescope gives astrophysicists analogous powers. It captures images of the universe in gamma rays, the most energetic form of light.

On April 12, one of the spacecraft's instruments - the Large Area Telescope (LAT), which was conceived of and assembled at the Department of Energy's SLAC National Accelerator Laboratory - detected its billionth extraterrestrial gamma ray.

Since gamma rays are often produced in violent processes, their observation sheds light on extreme cosmic environments, such as powerful star explosions, high-speed particle jets spewed out by supermassive black holes, and ultradense neutron stars spinning unimaginably fast. Gamma rays could also be telltale signs of dark matter particles - hypothetical components of invisible dark matter, which accounts for 85 percent of all matter in the universe.

"Since Fermi's launch in 2008, the LAT has made a number of important discoveries of gamma-ray emissions from exotic sources in our galaxy and beyond," says Robert Cameron, head of the LAT Instrument Science Operations Center (ISOC) at SLAC. The LAT has already collected hundreds of times more gamma rays than the previous-generation EGRET instrument on NASA's Compton Gamma-ray Observatory - an advance that has tremendously deepened insights into the production of this energetic radiation.

Enabling Discovery
Among the LAT discoveries are more than 200 pulsars - rapidly rotating, highly magnetized cores of collapsed stars that were up to 30 times more massive than the Sun. Before Fermi's launch, only seven of these objects were known to emit gamma rays. As pulsars spin around their axis, they emit "beams" of gamma rays like cosmic lighthouses. Many pulsars rotate several hundred times per second - that's tens of millions times faster than Earth's rotation.

"Understanding pulsars tells us about the evolution of stars because they are one possible end point in a star's life," Cameron says. "The LAT data have led us to totally revise our understanding of how pulsars emit gamma rays."

The LAT has also shown for the first time that novae - thermonuclear explosions on the surface of stars that have accumulated material from neighboring stars - can emit gamma rays. These data provide new details about the physics of burning stars, which is a crucial process for the synthesis of chemical elements in the universe.

Even more exotic gamma-ray sources detected by the LAT are microquasars. These objects are star-sized analogs of active galactic nuclei, with gas spinning around a black hole at the center. As the black hole devours matter from its surroundings, it ejects jets of charged particles traveling almost as fast as light into space, generating beams of gamma rays in the process.

At a galactic scale, such an ejection mechanism could have produced what is known as the Fermi bubbles - two giant areas above and below the center of the disk of our Milky Way galaxy that shine in gamma rays. Discovered by the LAT in 2010, these bubbles suggest that the supermassive black hole at the center of our galaxy once was more active than it is today.

Researchers also use the LAT to search for signs of dark matter particles in the central regions of the Milky Way and other galaxies. Theories predict that the hypothetical particles would produce gamma rays when they decay or collide and destroy each other.

"With the sensitivity we have achieved with the LAT, we should in principle be able to see such dark matter signatures," says SLAC's Seth Digel, who leads the Fermi group at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and SLAC. "But we haven't found any conclusive signals yet, and so far the LAT data can also be explained with other astrophysical sources."

Finally, the LAT has explored gamma ray sources closer to home, including gamma rays produced by thunderstorms in Earth's atmosphere, by solar flares and even by charged particles hitting the surface of the Moon.

Finding Needles in a Haystack
From its location on Fermi at an altitude of 330 miles, the LAT sees 20 percent of the sky at any given time. Every two orbits - each takes about 95 minutes - the instrument collects the data necessary for a gamma-ray map of the entire sky.

But identifying the right signals for the map is a little bit like finding needles in a haystack: For every gamma-ray photon, the LAT sees many more high-energy charged particles, called cosmic rays. Most of these background signals are rejected right away by hardware triggers and software filters in the LAT on Fermi, which reduces the rate of signals from 10,000 to 400 per second.

The remaining data are compressed, transmitted back to Earth and sent to NASA's Goddard Space Flight Center in Greenbelt, Maryland, where they get separated into three different datasets for the LAT, the GBM (Fermi's second scientific instrument, which monitors short-lived gamma-ray bursts) and spacecraft data.

The LAT data are transferred to the LAT ISOC at SLAC, where 1,000 computer cores automatically analyze the data stream and filter out even more background signals. 70 percent of all detected gamma rays are from Earth's atmosphere, leaving only two to three extraterrestrial gamma-ray signals per second out of the 10,000 initial detector events. These data are then sent back to NASA Goddard, where they are made publicly available for further analysis.

"The ISOC receives about 15 deliveries of LAT data throughout the day for a total of 16 gigabytes or three DVDs worth of data every day," Cameron says. "For each delivery, the entire process - from the time the data leave Fermi to the time the gamma rays get deposited in the public archive - takes about four hours."

Next year, the Fermi mission will reach its 10-year operations goal. What happens after that will largely depend on funding.

"With no successor mission planned, the LAT is in many ways irreplaceable, particularly for studies of low-energy gamma rays," Digel says. "The telescope is still going strong after all these years, and there is a lot of science left to be done."

An important new role for the LAT is to search for gamma-ray sources associated with gravitational wave events. These ripples in space-time occur, for example, when two black holes merge into a single one, as recently observed by the LIGO detector. This opens up the completely new field of gravitational wave astrophysics.

STELLAR CHEMISTRY
NASA's Fermi catches gamma-ray flashes from tropical storms
Greenbelt MD (SPX) Apr 25, 2017
About a thousand times a day, thunderstorms fire off fleeting bursts of some of the highest-energy light naturally found on Earth. These events, called terrestrial gamma-ray flashes (TGFs), last less than a millisecond and produce gamma rays with tens of millions of times the energy of visible light. Since its launch in 2008, NASA's Fermi Gamma-ray Space Telescope has recorded more than 4,000 TG ... read more

Related Links
SLAC National Accelerator Laboratory
Stellar Chemistry, The Universe And All Within It

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

STELLAR CHEMISTRY
ISS crew harvest new crop of vegetables grown in space

Joint Statement: The Fourth Meeting of the U.S.-Japan Comprehensive Dialogue on Space

One of first Soviet cosmonauts Gorbatko dies

Dem Senators call on Trump Admin to not cut NASA Education Progran funding

STELLAR CHEMISTRY
N. Korea's 'new missile' has unprecedented range: experts

NASA Affirms Plan for First Mission of SLS, Orion

Mining the moon for rocket fuel to get us to Mars

SSL satellite built for Bulgaria Sat arrives at Cape Canaveral for FOR falcon 9 launch

STELLAR CHEMISTRY
How hard did it rain on Mars

Deciphering the fluid floorplan of a planet

Mars Rover Opportunity Begins Study of Valley's Origin

Opportunity Reaches 'Perseverance Valley'

STELLAR CHEMISTRY
A cabin on the moon? China hones the lunar lifestyle

China tests 'Lunar Palace' as it eyes moon mission

China to conduct several manned space flights around 2020

Reach for the Stars: China Plans to Ramp Up Space Flight Activity

STELLAR CHEMISTRY
Satellite industry supports FCC proposal to reduce internet regulations for service providers

Allied Minds' portfolio company BridgeSat raises $6 million in Series A financing

AIA report outlines policies needed to boost the US Space Industry competitiveness

Blue Sky Network Targets Key Markets For Iridium SATCOM Solutions

STELLAR CHEMISTRY
Arralis launches plug and play Ka band chipset

Revolutionary new sunscreen features melanin-mimicking nanoparticles

HP Enterprise unveils computer 'for era of Big Data'

"Airbus Friedrichshafen: new satellite hub lays groundwork for the future"

STELLAR CHEMISTRY
Radio Detection of Lonely Planet Disk Shows Similarity with Stars

'Warm Neptune' Has Unexpectedly Primitive Atmosphere

Variable Winds on Hot Giant Exoplanet Help Study of Magnetic Field

ALMA eyes icy ring around young planetary system

STELLAR CHEMISTRY
Hubble spots moon around third largest dwarf planet

NASA asks science community for Europa Lander Instruments ideas

Waves of lava seen in Io's largest volcanic crater

Not So Great Anymore: Jupiter's Red Spot Shrinks to Smallest Size Ever




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement