Suzaku Shows Clearest Picture Yet of Perseus Galaxy Cluster
X-ray observations made by the Suzaku observatory provide the clearest picture to date of the size, mass and chemical content of a nearby cluster of galaxies. The study also provides the first direct evidence that million-degree gas clouds are tightly gathered in the cluster’s outskirts.
Suzaku explored faint X-ray emission of hot gas across two swaths of the Perseus Galaxy Cluster. The images, which record X-rays with energies between 700 and 7,000 electron volts in a combined exposure of three days, are shown in two false-color strips. Bluer colors indicate less intense X-ray emission. The dashed circle is 11.6 million light-years across and marks the so-called virial radius, where cold gas is now entering the cluster. Red circles indicate X-ray sources not associated with the cluster. Inset: An image of the cluster’s bright central region taken by NASA’s Chandra X-ray Observatory is shown to scale. Credits: NASA/ISAS/DSS/A. Simionescu et al.; inset: NASA/CXC/A. Fabian et al.
Suzaku is sponsored by the Japan Aerospace Exploration Agency (JAXA) with contributions from NASA and participation by the international scientific community. The findings will appear in the March 25 issue of the journal Science.
Galaxy clusters are millions of light-years across, and most of their normal matter comes in the form of hot X-ray-emitting gas that fills the space between the galaxies.
In a supernova remnant known as the Jellyfish Nebula, Suzaku detected X-rays from fully ionized silicon and sulfur – an imprint of higher-temperature conditions immediately following the star’s explosion. The nebula is about 65 light-years across.
Shows the X-ray/optical composite image cropped tot he XIS field-of-view. Credit: JAXA/NASA/Suzaku, Tom Bash and John Fox/Adam Block/NOAO/AURA/NSF
shows the X-ray/optical composite with the XIS field-of-view indicated with a white box. Credit: JAXA/NASA/Suzaku, Tom Bash and John Fox/Adam Block/NOAO/AURA/NSF
Studies of two supernova remnants using the Japan-U.S. Suzaku observatory have revealed never-before-seen embers of the high-temperature fireballs that immediately followed the explosions. Even after thousands of years, gas within these stellar wrecks retain the imprint of temperatures 10,000 times hotter than the sun’s surface.
“This is the first evidence of a new type of supernova remnant – one that was heated right after the explosion,” said Hiroya Yamaguchi at the Institute of Physical and Chemical Research in Japan.
A supernova remnant usually cools quickly due to rapid expansion following the explosion. Then, as it sweeps up tenuous interstellar gas over thousands of years, the remnant gradually heats up again.
Capitalizing on the sensitivity of the Suzaku satellite, a team led by Yamaguchi and Midori Ozawa, a graduate student at Kyoto University, detected unusual features in the X-ray spectrum of IC 443, better known to amateur astronomers as the Jellyfish Nebula.
The remnant, which lies some 5,000 light-years away in the constellation Gemini, formed about 4,000 years ago. The X-ray emission forms a roughly circular patch in the northern part of the visible nebulosity.
GX 339-4, illustrated here, is among the most dynamic binaries in the sky, with four major outbursts in the past seven years. In the system, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. Credit: ESO/L. Calçada
Studies of one of the galaxy’s most active black-hole binaries reveal a dramatic change that will help scientists better understand how these systems expel fast-moving particle jets.
Binary systems where a normal star is paired with a black hole often produce large swings in X-ray emission and blast jets of gas at speeds exceeding one-third that of light. What fuels this activity is gas pulled from the normal star, which spirals toward the black hole and piles up in a dense accretion disk.
“When a lot of gas is flowing, the dense disk reaches nearly to the black hole,” said John Tomsick at the University of California, Berkeley. “But when the flow is reduced, theory predicts that gas close to the black hole heats up, resulting in evaporation of the innermost part of the disk.” Never before have astronomers shown an unambiguous signature of this transformation.
To look for this effect, Tomsick and an international group of astronomers targeted GX 339-4, a low-mass X-ray binary located about 26,000 light-years away in the constellation Ara. There, every 1.7 days, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. With four major outbursts in the past seven years, GX 339-4 is among the most dynamic binaries in the sky.
