Nav: Home

Suzaku explains cosmic powerhouses

December 20, 2007

GREENBELT, Md. - By working in synergy with a ground-based telescope array, the joint Japanese Aerospace Exploration Agency (JAXA)/NASA Suzaku X-ray observatory is shedding new light on some of the most energetic objects in our galaxy, but objects that remain shrouded in mystery.

These cosmic powerhouses pour out vast amounts of energy, and they accelerate particles to almost the speed of light. But very little is known about these sources because they were discovered only recently. "Understanding these objects is one of the most intriguing problems in astrophysics," says Takayasu Anada of the Institute for Space and Astronautical Science in Kanagawa, Japan. Anada is lead author of a paper presented last week at a Suzaku science conference in San Diego, Calif.

These mysterious objects have been discovered in just the last few years by an array of four European-built telescopes named the High Energy Stereoscopic System (H.E.S.S.), located in the African nation of Namibia. H.E.S.S. indirectly detects very-high-energy gamma rays from outer space. These gamma rays are the highest-energy form of light ever detected from beyond Earth, so H.E.S.S. and other similar arrays have opened up a new branch of astronomy.

The gamma rays themselves are absorbed by gases high up in Earth's atmosphere. But as the gamma rays interact with air molecules, they produce subatomic particles that radiate a blue-colored light known as Cherenkov radiation. H.E.S.S. detects this blue light, whose intensity and direction reveals the energy and position of the gamma-ray source.

The H.E.S.S. observations were groundbreaking, but the array's images aren't sharp enough to reveal the exact location where particles are being accelerated or how the particles are being accelerated. To solve this problem, several teams aimed Suzaku in the direction of some of these H.E.S.S. sources. Any object capable of emitting high-energy gamma rays will also produce X-rays, and Suzaku is particularly sensitive to high-energy (hard) X-rays.

When Anada and his colleagues pointed Suzaku at a source known as HESS J1837-069 (the numerals express the object's sky coordinates), the X-ray spectrum closely resembled X-ray spectra of pulsar wind nebulae -- gaseous clouds that are sculpted by winds blown off by collapsed stars known as pulsars. Pulsar wind nebulae emit hard X-rays, and their X-ray output remains relatively constant over long timescales. "The origin of the gamma-ray emission from HESS J1837-069 remains unclear, but we suspect that this source is a pulsar wind nebula from the Suzaku observation," says Anada.

NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton X-ray Observatory have revealed that other H.E.S.S. sources are also pulsar wind nebulae. These combined gamma-ray and X-ray observations are revealing that pulsar wind nebulae are more common and more energetic than astronomers had expected.

Another group, led by Hironori Matsumoto of the University of Kyoto in Japan, targeted Suzaku on HESS J1614-518. This source belongs to a class of objects known as "dark particle accelerators" because their ultrahigh energies suggest they are accelerating particles to near-light speed, turning them into cosmic rays. But what are these objects, and what kinds of particles are being accelerated"

Although the nature of these objects remains a mystery, Suzaku's observations do reveal the identity of the particles. When electrons are accelerated to high speeds, they spiral around magnetic field lines that permeate space, generating copious X-rays. But since protons are 2,000 times more massive than electrons, they emit few X-rays. Matsumoto and his colleagues reported at the conference that HESS J1614-518 is a very weak X-ray emitter. "This result strongly suggests that high-energy protons are being produced in this object," says Matsumoto.

Suzaku also observed two other H.E.S.S. dark particle accelerators, but found no obvious X-ray counterparts at the H.E.S.S. positions. These sources must also be weak X-ray emitters, indicating they are accelerating mostly protons. As Matsumoto says, "Using the high sensitivity of the Suzaku satellite, we can find strong candidates for the origin of cosmic rays."

Launched in 2005, Suzaku is the fifth in a series of Japanese satellites devoted to studying celestial X-ray sources. Managed by JAXA, this mission is a collaborative effort between Japanese universities and institutions and NASA Goddard.

NASA/Goddard Space Flight Center

Related Gamma Rays Articles:

Medical gamma-ray camera is now palm-sized
Researchers invented a Compton camera of 580g which visualizes gamma rays of arbitrary energies, and succeeded in achieving a high-resolution, multicolor 3-D molecular image of a live mouse administered with three different radioactive tracers in just two hours.
NASA's Fermi sees gamma rays from 'hidden' solar flares
NASA's Fermi Gamma-ray Space Telescope has observed high-energy light from solar eruptions located on the far side of the sun -- light it shouldn't be able to see.
Supercomputers fire lasers to shoot gamma ray beam
Supercomputer simulations showed UT Austin scientists a new way to generate controlled beam of gamma rays from lasers.
Novel portable diagnostic tool pairs optical and gamma imaging
Bigger isn't always better, especially when it comes to a new and surprisingly portable molecular imaging system that combines optical imaging at the surface level and scintigraphy, which captures the physiological function of what lies beneath, announced developers at the 2016 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI).
Gamma-retroviruses preferentially integrate near cancer-associated genes
Identifying the sites where gamma-retroviruses commonly insert into the genome may help to identify genes associated with specific cancer types, according to a study published April 20, 2016 in the open-access journal PLOS ONE by Kathryn Gilroy at the University of Glasgow, UK, and colleagues.
Galactic center's gamma rays unlikely to originate from dark matter, evidence shows
Studies by two independent groups from the US and the Netherlands have found that gamma ray signals from the inner galaxy come from a new source rather than from the collision of dark matter particles.
Gamma rays from distant galaxy tell story of an escape
A flare of very high-energy gamma rays emitted from a galaxy halfway across the universe has put new bounds on the amount of background light in the universe and given astrophysicists clues to how and where such gamma rays are produced.
VERITAS detects gamma rays from galaxy halfway across the visible universe
In April 2015, after traveling for about half the age of the universe, a flood of powerful gamma rays from a distant galaxy slammed into Earth's atmosphere.
NASA's Swift spots its thousandth gamma-ray burst
NASA's Swift spacecraft has detected its 1,000th gamma-ray burst (GRB).
Detection of gamma rays from a newly discovered dwarf galaxy may point to dark matter
A newly discovered dwarf galaxy orbiting our own Milky Way has offered up a surprise -- it appears to be radiating gamma rays, according to an analysis by physicists at Carnegie Mellon, Brown, and Cambridge universities.

Related Gamma Rays Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...