An international group of researchers assembled at the Esrange Space Center in Kiruna, Sweden, on Tuesday to attend the launch of XL-Calibur. It is a balloon-borne telescope that is supposed to measure X-ray emissions in our galaxy.
X-Calibur’s current mission is to land in northern Canada on an unknown date after cruising over the north Atlantic Ocean. The task is going to collect data on several targets: The stellar-mass black hole Cygnus X-1, the Crab Nebula and Crab Pulsar, and two flaring X-ray sources in the Milky Way. NASA’s Wallops Flight Facility in Virginia declared the launch on its official Twitter account on Monday.
XL-Caliber is a partnership between approximately 50 scientists from the United States, Japan, and Sweden supervised by principal investigator Henric Krawczynski of Washington University in St. Louis. The project intends to collect data on the way the magnetic fields and scattering can lead to X-ray polarization, which can ultimately offer the astronomers a better knowledge of black holes and neutron stars, two sources of X-rays.
Specifically, XL-Calibur is built to study X-ray polarization in order to “improve our constraints on the properties of black holes and neutron stars, better understand the physics of accretion onto black holes and neutron stars, as well as test predictions of strong-field QED [quantum electrodynamics] and strong-field gravity,” as per the project’s official website. A detailed description of the way the X-ray polarization sensors aboard XL-Calibur can achieve these goals was published on the preprint server arXiv in 2019.
