Credit: JAXA; NASA
Bumps in the Night
The X-ray Imaging and Spectroscopy Mission, or XRISM, is an X-ray space observatory built by the Japanese Aerospace Exploration Agency (ISAS/JAXA), NASA and the European Space Agency (ESA). As its name implies, XRISM carries on board two instruments, a high resolution X-ray spectrometer (called Resolve) and a wide field of view X-ray camera (called XTEND). XTEND not only measures the position of X-ray sources on the sky, but also provides time-sensitive medium-resolution X-ray spectra of them as well. Since XTEND has such a large field of view (larger than the apparent size of the full moon as viewed from earth) XTEND images not only include the target of interest, but other surrounding sources as well. The image above is an early-release XTEND image of an X-ray source called V4641 Sgr, a variable X-ray binary system consisting of a black hole orbiting a massive star. The image shows the four detectors that make up the complete XTEND field of view. V4641 Sgr is the bright X-ray source in the upper left detector, showing the characteristic cross-like shape produced by the XTEND mirror; two other bright sources near the left and right edge of the field of view are instrumental calibration sources. XTEND is particularly sensitive to changes in the brightness of known X-ray sources, and to the sudden appearance of previously unknown sources that may lie within its field of view, making it an excellent detector of transient sources. To take advantage of this important capability, XTEND images are routinely scanned for the presence of transient X-ray sources. To date, the XTEND Transient Search has found more than three dozen new transients, including an outburst from a putative white dwarf, flares from young stars, flares from interacting binary systems, and more.
Published: April 28, 2025
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 28-Apr-2025 11:45:44 EDT