Unusual short burst of X-rays coming from slowest-spinning neutron star
A new record-holder for the slowest spinning neutron star has been found thanks to clues first detected by NASA’s Swift space observatory, whose science and flight operations are controlled by Penn State from the University Park campus. Spinning neutron stars are the class of stars with the most powerful magnetic fields in the universe. Swift’s X-Ray Telescope captured a short burst of unusual X-rays on June 22, 2016 coming from an object roughly 9,000 light-years from Earth.
The X-ray burst detected by Swift had intense, extremely rapid fluctuations measured in milliseconds. This intriguing fingerprint quickly triggered additional observations by teams of astronomers worldwide who obtained observing time with additional space observatories including NASA’s Chandra X-ray Observatory and NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR). A paper by one team that includes astronomers at Penn State, NASA, Los Alamos National Laboratory, and universities in Italy, the United Kingdom, and Germany has been accepted for future publication in the Monthly Notices of the Royal Astronomical Society.
“Observations with multiple space telescopes have revealed that, while other neutron stars spin multiple times a minute, this object rotates only once about every 6.5 hours — making it by far the slowest-spinning star in its class discovered to date,” said David Burrows, professor of astronomy and astrophysics at Penn State. “The data collected by Chandra show that this object has properties of a magnetar — a type of neutron star with extremely powerful magnetic fields trillions of times as powerful as those of the Sun that can erupt with enormous bursts of energy.”
The object is located in the center of a colorful cloud of material consisting of the remains of an ancient star that exploded as a massive supernova. This supernova remnant, named RCW103, and the intriguing object at its center, can be detected with an X-ray telescope like the one on Swift but is invisible at wavelengths that human eyes can see.
“This object has been of interest to Penn State astronomers for a long time,” Burrows said. “Gordon Garmire, now a Penn State Evan Pugh Professor Emeritus of Astronomy and Astrophysics, discovered in 1979 that the supernova surrounding this object was producing X-rays. He also discovered a huge X-ray flare shooting out into space from this object.”
Now the Swift observatory, which first detected the very unusual, very short X-ray spike produced by this object, has helped to reveal at the heart of this supernova remnant an object that the data collected so far suggest could be one of the most extreme rotating magnetized neutron stars ever detected; in other words, an extreme magnetar. NASA has confirmed that new data from this trio of high-energy telescopes, and archival data from Chandra, Swift and the European Space Agency’s XMM-Newton observatory, all show that the object has the properties of a magnetar, making it only the 30th known.