Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Iowa State researchers help detect very-high-energy gamma rays from Crab pulsar

07.10.2011
Iowa State University astrophysicists are part of an international team that unexpectedly discovered very-high-energy gamma rays from the already well-known Crab pulsar star.

The team's findings are published in the Oct. 7 issue of the journal Science.

"This is the first time very-high-energy gamma rays have been detected from a pulsar - a rapidly spinning neutron star about the size of the city of Ames but with a mass greater than that of the sun," said Frank Krennrich, an Iowa State professor of physics and astronomy and a co-author of the paper.

The discovery was the work of three post-doctoral researchers – including Martin Schroedter, who left Iowa State last year for a position at the Fred Lawrence Whipple Observatory near Amado, Ariz.

The researchers' finding was a surprise, said Amanda Weinstein, an Iowa State assistant professor of physics and astronomy. Astrophysicists started looking for very-high-energy gamma rays from the Crab pulsar decades ago and had never found them with energies greater than 25 billion electron volts.

This time, using the $20 million Very Energetic Radiation Imaging Telescope Array System (VERITAS) in southern Arizona, the researchers discovered pulsed gamma rays from the Crab pulsar that exceeded energies of 100 billion electron volts.

Krennrich said such high energies can't be explained by the current understanding of pulsars.

Pulsars are compact neutron stars that spin rapidly and have a very strong magnetic field, Krennrich said. The spin and magnetism pull electrons from the star and accelerate them along magnetic field lines, creating narrow bands of "curvature radiation."

Krennrich and Weinstein said curvature radiation doesn't explain the very-high-energy gamma rays reported in the Science paper. And so astrophysicists need to develop new ideas about pulsars and how they create gamma rays.

Gamma rays are a form of high-energy electromagnetic radiation. They have energies of one million to several trillion electron volts; the energy of visible light is one electron volt.

Even with their very high energies, gamma rays can't penetrate the earth's atmosphere. When they hit the atmosphere, they create showers of electrons and positrons that create a blue light known as Cerenkov radiation. Those showers move very fast. And they're not very bright.

And so it takes a very sensitive instrument such as VERITAS to detect those rays. VERITAS features four, 12-meter reflector dishes covered with 350 mirrors. All those mirrors direct light into cameras mounted in front of each dish. Each camera is about 7 feet across and contains 499 tube-shaped photon detectors or pixels.

All those detectors were built in a laboratory on the fourth floor of Iowa State's Zaffarano Physics Addition. The assembly took about $1 million and a lot of work by a team of Iowa State researchers.

Weinstein, then working as a post-doctoral researcher at the University of California, Los Angeles, helped design and build the VERITAS array trigger. The trigger is an electronics system that works in real-time to determine which telescope observations contain useful data that should be recorded for analysis.

Researchers believe a better understanding of gamma rays could help them explore distant regions of space, help them look for evidence of dark matter, determine how much electromagnetic radiation the universe has produced, answer questions about the formation of stars and help explain the origins of the most energetic radiation in the universe.

The three lead authors of the Science paper are Schroedter; Andrew McCann of McGill University in Montreal; and Nepomuk Otte of the University of California, Santa Cruz and now at the Georgia Institute of Technology in Atlanta. Iowa State co-authors are Krennrich; Weinstein; Matthew Orr, a post-doctoral research associate in physics and astronomy; Arun Madhavan, a doctoral student in physics and astronomy; and Asif Imran, a former Iowa State doctoral student who's now at Los Alamos National Laboratory in New Mexico.

The research project was supported by the U.S. Department of Energy Office of Science, the National Science Foundation, the Smithsonian Institution, the National Sciences and Energy Research Council of Canada, Science Foundation Ireland, and the Science and Technology Facilities Council in the United Kingdom.

There's more than a gamma-ray discovery in this particular research paper, Weinstein said. There's also a lesson about scientific discovery.

"Because this was something people didn't expect, it took courage to pursue this study," she said. "The lesson is you keep making your instruments better and you keep looking."

Contacts:

Frank Krennrich
Physics and Astronomy
515-294-3736
krennich@iastate.edu
Amanda Weinstein
Physics and Astronomy
515-294-6448
amandajw@iastate.edu
Mike Krapfl
News Service
515-294-4917
mkrapfl@iastate.edu

Frank Krennrich | EurekAlert!
Further information:
http://www.iastate.edu

More articles from Physics and Astronomy:

nachricht New thruster design increases efficiency for future spaceflight
16.08.2017 | American Institute of Physics

nachricht Tracking a solar eruption through the solar system
16.08.2017 | American Geophysical Union

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: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>