(ORDO NEWS) — A new telescope designed to study the tortuous X-ray universe has just sent back its first ever image data.
The Imaging X-Ray Polarimetry Explorer (IXPE), a joint project between NASA and the Italian Space Agency, has set its sights on one of the most famous explosions in the Milky Way: Cassiopeia A.
Located 11,000 light-years away, this expanding remnant of a star thought to have exploded in the 1690s is one of the best-studied objects in the Milky Way, and for good reason – it has provided invaluable insight into supernovae.
Cassiopeia A emits light in several wavelengths, including radio, optical and, of course, X-rays. In fact, the first scientific image taken by NASA’s other X-ray observatory, Chandra, was also taken by Cassiopeia A.
But IXPE shows us this object in a way we haven’t seen it yet.
“The IXPE image of Cassiopeia A is as historic as the Chandra image of the same supernova remnant,” says astronomer and IXPE principal investigator Martin C. Weisskopf of NASA’s Marshall Space Flight Center.
“It demonstrates the potential of IXPE to provide new, never-before-seen information about Cassiopeia A, which is currently under analysis.”
There is a lot going on in Cassiopeia A. Before its death, the progenitor star was a massive object that, when it ran out of fuel, became unstable, ejecting its outer layers to create a cloud of circumstellar material. Therefore, when the supernova did occur, the shock wave did not enter untouched space, but into a relatively dense cloud.
The shock waves and magnetic fields generated in this intense environment can create synchrotrons that accelerate electrons, generating high-energy X-rays.
Chandra has done fascinating research; for example, combining the Chandra data with light at other wavelengths has allowed astronomers to map the different elements in Cassiopeia A that were erupted in the giant explosion.
IXPE is specifically designed to study the polarization of X-rays. When light is emitted from a source, its waves are oriented in all directions. When light collides with a medium, this orientation can change.
For example, when passing through a gas, it can absorb certain orientations. Reflecting off objects, light can also change the orientation of some wavelengths. We call this effect polarization.
For an object like Cassiopeia A, detailed polarization data will tell us more about the environment inside the supernova remnant. This will provide more information about how light is absorbed and reflected, as well as the interweaving of magnetic fields created by the supernova.
“Future polarization images of IXPE should reveal the mechanisms behind this famous space accelerator,” says Stanford University astronomer Roger Romani.
“To refine some of these details, we have developed a way to make IXPE measurements even more accurate using machine learning methods. We look forward to what we will discover when we analyze all the data.”
The telescope, while in low Earth orbit, will also investigate the polarization of X-rays from some of the most energetic sources in the Milky Way and beyond.
These include neutron stars, pulsars, magnetars, black holes and quasar galaxies, which shine with some of the brightest light in the universe. IXPE will also map light intensity, time of occurrence and position in the sky.
Cassiopeia A is a great place to start.
“The IXPE image of Cassiopeia A is simply stunning,” says astronomer and IXPE principal investigator Paolo Soffitta of the National Institute of Astrophysics (INAF) in Italy, “and we look forward to analyzing the polarimetric data to learn even more about this supernova remnant.”
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