XRISM’s X-ray mirrors and star trackers are mounted on the front of the craft (left), as shown in this rendering. Credit: NASA Goddard Space Flight Center Conceptual Imaging Laboratory
The XRISM (X-Ray Imaging and Spectroscopy Mission) mission is not the first of its kind, but the cutting-edge spectroscopic instruments on board have opened new doors for high-energy astrophysics.
Active galactic nuclei (AGN) – supermassive black holes that actively devour material and glow in the resulting chaos – have always held mysteries for astrophysicists. Now, a year after XRISM’s launch in September 2023, its first results have revealed key findings about the structure of an AGN and traced a supernova remnant by imaging the flow of superheated iron atoms nearby. The results come from the commissioning phase of XRISM, to test – and showcase – the capabilities of the new observatory in orbit. More than 100 international researchers analyzed XRISM data to produce the results of two new studies.
“It’s really exciting to be able to collect X-ray spectra with such unprecedented high resolution, particularly for the hottest plasmas in the universe,” said Lia Corrales, co-author of both XRISM publications and an astronomer at the University of Michigan. in Ann Arbor, in a press release.
At the top of the solution food chain
XRISM was built through a collaboration between the Japan Aerospace Exploration Agency (JAXA) and NASA, with participation from the European Space Agency (ESA), and is intended to work in concert with its predecessors such as the telescope XMM-Newton X-ray Observatory and the Chandra X-ray Observatory.
The new observatory uses two instruments, including Xtend, an imager that focuses on the soft X-ray end of the spectrum. But researchers are more excited about Resolve, a spectroscopy instrument with a twist: It’s a microcalorimeter that measures not the X-rays as they enter the instrument, but how much they heat the little detector when they hit it. The incredible sensitivity of this setup gives Resolve unprecedented spectral resolution, justifying its name and producing highly detailed spectra with which to analyze XRISM targets.
“Resolve will allow us to see the shapes [spectral] lines in a way never possible before,” said Brian Williams, an XRISM project scientist at NASA’s Goddard Space Flight Center, in a press release earlier this year, “enabling us to determine not only the abundance of various elements present, but also their temperatures, densities and directions of movement at unprecedented levels of precision.”
XRISM rules with an iron fist
To test the mettle of the new telescope, Resolve’s power was applied to a supernova remnant in the Large Magellanic Cloud called N132D, whose massive original star collapsed in a supernova explosion about 3,000 years ago, leaving behind itself a hot bubble of gas in the atmosphere. interstellar medium. During the supernova, iron was released and heated to a staggering 18 billion degrees Fahrenheit (10 billion degrees Celsius). The study has been accepted for publication in Publications of the Astronomical Society of Japan.
At this temperature, XRISM easily tracked down the iron elements and revealed that the shape of SNR N132D is not the expected spherical bubble, but is instead torus- or donut-shaped. Additionally, XRISM provided information on the speed and direction of the hot plasma; the research team managed to measure the speed and found that the torus is expanding at a speed of 4.3 million km/h.
“These new observations… show the mission’s exceptional ability to explore the high-energy universe,” said Matteo Guainazzi, ESA’s XRISM project scientist, in a press release.
Bent black hole
Another pre-released study is also based on first-look data from light years away.
Previous radio and infrared observations had already shown that the accretion disk surrounding the supermassive black hole is also torus-shaped, as is the material inside the disk. However, with XRISM’s advanced spectroscopic instruments, researchers can now track the distribution of plasma orbiting and falling into the black hole.
Iron elements within the AGN are key ingredients for this and future studies to map the structure of the accretion disc.
“Resolve allows us to characterize the multistructured, multitemperature environment of SMBHs in a way that was not possible before,” Corrales said.
XRISM is only now entering the General Observer (GO) phase, during which scientists from around the world will be able to submit objectives and study the results. The next few years will see a whole new universe of X-rays open up to understanding.
