Mark Megahan
Astronomers are having a blast with their newest toy, the Imaging X-Ray Polarimetry Explorer. It’s a telescope specially designed to gaze deep into the “twisted” way the universe appears in ultra-high frequency wavelengths. Even better, it does it from above the atmosphere in low Earth orbit.
First X-Ray images
The first high-quality images captured by the X-Ray explorer image “one of the most famous explosions in the Milky Way.” None other than Cassiopeia A. Located a mere 11,000 light-years away, what we are seeing is “the expanding remnant of a star thought to have been observed exploding in the 1690s.”
While it’s “one of the most well-studied objects in the Milky Way.” The supernova shows off all her magnificent beauty in a composite photo from Hubble, Spitzer, and Chandra data.
The new composite image blending Chandra data in blue with IXPE data in Magenta lets the structure appear. Meanwhile, the core elements stand out bold and stark when just the IXPE light intensity is depicted.
Cassiopeia A is such a great target for the IXPE to start with because it “emits light in multiple wavelengths, including radio, optical, and, of course, X-ray.” The supernova was also the first object imaged by Chandra when it came online.
According to IXPE principal investigator Martin C. Weisskopf, “The IXPE image of Cassiopeia A is as historic as the Chandra image of the same supernova remnant.”
This time, it’s in X-ray. “It demonstrates IXPE’s potential to gain new, never-before-seen information about Cassiopeia A, which is under analysis right now.”
A lot going on
One of the reasons astronomers like Cassiopeia A so much is because there’s “a lot going on.” Before it blew up, “the precursor star was a massive object that, as it ran out of fuel, became unstable, ejecting its outer layers to create a cloud of circumstellar material.”
When it finally went supernova, “the shock wave was not entering pristine space, but a relatively dense cloud.” That shows some interesting things in the X-ray band.
The “shocks and magnetic fields” hurtling out from this “intense environment” can create “synchrotrons that accelerate electrons.” That’s where all the high-energy X-ray radiation comes from.
While Chandra has done some amazing things, “IXPE is designed specifically to study the way X-rays are polarized.” Between the two of them, they make a winning combination.
Just like sunlight scatters to create glare, which is eliminated by polarizing sunglasses, when starlight “is emitted from a source, its waves are oriented in all directions. When that light encounters a medium, that can change.” IXPE is sensitive to that polarization.
“Passing through gas, for instance, can absorb some orientations. Bouncing off things can also alter the orientation of some wavelengths.” Looking at the polarization of X-ray radiation in Cassiopeia A is hoped to reveal “the mechanisms at the heart of this famous cosmic accelerator.“
