ise. "As more and more are discovered, new insights about what is happening in the galaxy's spiral arms begin to emerge," Beckmann said.
IGR J16283-4838 revealed itself during an outburst on or near its surface. Neutron stars such as this are often part of binary systems, orbiting a normal star. Occasionally, gas from the normal star, lured by gravity, crashes onto the surface of the neutron star and releases a great amount of energy. Outbursts can last for weeks before the system returns to dormancy for months or years.
INTEGRAL, the Rossi Explorer and Swift all detect X-rays and gamma rays, which are far more energetic than the visible light our eyes can see. Yet each satellite has different capabilities. INTEGRAL has a large field of view, enabling it to scan the Milky Way galaxy for neutron star and black hole activity. Swift contains a high-resolution X-ray telescope, which allowed scientists to zero in on IGR J16283-4838. The Rossi Explorer has a timing spectrometer, a device used to uncover properties of the light source, such as speed and rapid variations on the order of a millisecond.
Simona Soldi, a doctoral candidate at the INTEGRAL Science Data Centre in Geneva, discovered the new bright source on April 7 using the spacecraft. "We are always hunting for new sources, and it's exciting when we find something so elusive," Soldi said. "How many more like this are out there?"
NASA's Swift X-ray Telescope captured this image from the IGR J16283-4838. The neutron star and its companion appear as one ball of X-ray light.
Click on image to enlarge.
(Credit: NASA/Swift/Volker et al.)
Because gamma rays are hard to focus into sharp images, the science team used the X-ray Telescope aboard Swift on April 13 and 15 to determine a precise location. Swift confirmed that the light was "highly absorbed," which means the binary system was filled with dense gas from the stellar wind of the companion star. Starting on April 14, scientists used the Rossi Explorer to observe the source as it faded away. This observation revealed a familiar light signature clinching the case for a fading "high-mass X-ray binary" with a neutron star.
"Piece by piece we solved this puzzle," said Dr. Jamie Kennea, Swift science team member at Penn State. "Swift was built primarily to detect gamma-ray bursts, so it was a thrill to use the X-ray Telescope to do something quite different, to discover a neutron star."
INTEGRAL launched in 2002, and the Rossi Explorer and Swift launched in 1995 and 2004, respectively.