First Glance into the X-ray Cosmos Unveiled by NASA/JAXA XRISM Mission

The Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) observatory has unveiled an initial preview of the unprecedented data it is poised to gather once scientific operations commence later this year.

The satellite’s scientific team has shared a snapshot featuring a cluster of hundreds of galaxies and a spectrum showcasing stellar remnants in a nearby galaxy. This snapshot provides scientists with a detailed insight into the chemical composition of the observed celestial bodies.

“XRISM will offer the international scientific community a fresh perspective on the concealed X-ray sky,” stated Richard Kelley, the U.S. principal investigator for XRISM at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We will not only witness X-ray images of these sources but also delve into their compositions, movements, and physical conditions.”

The Resolve instrument of XRISM (X-ray Imaging and Spectroscopy Mission) has successfully collected data from the supernova remnant N132D in the Large Magellanic Cloud, producing the most intricate X-ray spectrum of the object to date. This spectrum unveils distinctive peaks linked to elements such as silicon, sulfur, argon, calcium, and iron. Inset on the right showcases an image of N132D captured by XRISM’s Xtend instrument. Credit: JAXA/NASA/XRISM Resolve and Xtend

XRISM (pronounced “crism”) is spearheaded by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, and features contributions from ESA (European Space Agency). The mission, launched on September 6, 2023, is specifically designed to detect X-rays with energies reaching up to 12,000 electron volts, focusing on studying the universe’s hottest regions, largest structures, and objects with the most formidable gravity. To put this into perspective, the energy of visible light typically ranges from 2 to 3 electron volts.

Comprising two key instruments, Resolve and Xtend, each situated at the focal point of an X-ray Mirror Assembly crafted at Goddard, XRISM promises to unlock new insights into celestial phenomena.

Resolve, a microcalorimeter spectrometer jointly developed by NASA and JAXA, operates within a refrigeration-sized container of liquid helium, maintaining a temperature just a fraction of a degree above absolute zero. When an X-ray interacts with Resolve’s 6-by-6-pixel detector, it causes a measurable warming of the device corresponding to the X-ray’s energy. This innovative approach allows Resolve to provide unprecedented information about the energy levels of individual X-rays, enhancing our understanding of the sources under investigation.

The supernova remnant N132D is situated in the central region of the Large Magellanic Cloud, a dwarf galaxy located approximately 160,000 light-years away. XRISM’s Xtend instrument skillfully captured the X-ray image of the remnant, as depicted in the inset. N132D spans about 75 light-years at its widest point. Despite its pronounced brightness in X-rays, the remnants of this stellar event remain nearly imperceptible in the ground-based background view captured in optical light. Credit: Inset, JAXA/NASA/XRISM Xtend; background, C. Smith, S. Points, the MCELS Team and NOIRLab/NSF/AURA

The mission team utilized Resolve to scrutinize N132D, a supernova remnant and one of the most luminous X-ray sources in the Large Magellanic Cloud, a dwarf galaxy positioned approximately 160,000 light-years away in the southern constellation Dorado. The expanding debris from this celestial event is estimated to be around 3,000 years old and originated when a star, roughly 15 times the mass of the Sun, depleted its fuel, underwent collapse, and ultimately exploded.

The Resolve spectrum obtained from this study reveals distinctive peaks associated with silicon, sulfur, calcium, argon, and iron. This spectrum represents the most detailed X-ray analysis of the object to date, showcasing the remarkable scientific capabilities that the mission will unleash once regular operations commence later in 2024.

“These elements were forged in the original star and then blasted away when it exploded as a supernova,” explained Brian Williams, NASA’s XRISM project scientist at Goddard. “Resolve will enable us to discern the shapes of these lines in a manner previously unattainable, enabling us to determine not only the abundances of the various elements present but also their temperatures, densities, and directions of motion at unprecedented levels of precision. From there, we can piece together information about the original star and the explosion.”

XRISM’s second instrument, Xtend, serves as an X-ray imager developed by JAXA. With its expansive field of view, Xtend enables XRISM to observe an area approximately 60% larger than the average apparent size of the full moon.

The X-ray imager, Xtend, from XRISM successfully captured the galaxy cluster Abell 2319 in a striking display of purple, outlined by a white border delineating the detector’s reach. The background features a ground-based image presenting the same area in visible light. Credit: JAXA/NASA/XRISM Xtend; background, DSS

Xtend captured an X-ray image of Abell 2319, a rich galaxy cluster about 770 million light-years away in the northern constellation Cygnus. It’s the fifth brightest X-ray cluster in the sky and is currently undergoing a major merger event.

The cluster is 3 million light-years across and highlights Xtend’s wide field of view.

“Even before the end of the commissioning process, Resolve is already exceeding our expectations,” said Lillian Reichenthal, NASA’s XRISM project manager at Goddard. “Our goal was to achieve a spectral resolution of 7 electron volts with the instrument, but now that it’s in orbit, we’re achieving 5. What that means is we’ll get even more detailed chemical maps with each spectrum XRISM captures.”

Resolve is performing exceptionally and already conducting exciting science despite an issue with the aperture door covering its detector. The door, designed to protect the detector before launch, has not opened as planned after several attempts. The door blocks lower-energy X-rays, effectively cutting the mission off at 1,700 electron volts compared to the planned 300. The XRISM team will continue to explore the anomaly and is investigating different approaches to opening the door. The Xtend instrument is unaffected.

NASA’s XRISM General Observer Facility, hosted at Goddard, is accepting proposals for observations from members of U.S. and Canadian institutions through Thursday, April 4. Cycle 1 of XRISM General Observer investigations will begin in the summer of 2024.

XRISM is a collaborative mission between JAXA and NASA, with participation by ESA. NASA’s contribution includes science participation from the Canadian Space Agency.

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