XRISM detects iron fingerprints from nearby active galaxies

The Resolve instrument aboard XRISM (X-ray Imaging Spectroscopy Mission) collected data from the center of galaxy NGC 4151, where a supermassive black hole is slowly consuming material in the surrounding accretion disk. The resulting spectrum shows the presence of iron with a peak around 6.5 keV and a dip around 7 keV, making this light thousands of times more energetic than what our eyes can see. Background: An image of NGC 4151 created from a combination of X-ray, optical, and radio light. Image credit: Spectrum: JAXA/NASA/XRISM Resolve. Background: X-ray, NASA/CXC/CfA/J.Wang et al. Optics, Isaac Newton Telescope Group, La Palma/Jacobus Kaptein Telescope. Radio, NSF/NRAO/VLA Alt text: His XRISM spectrum of NGC 4151 and a multiwavelength snapshot of the background galaxy. Description: The spectral image is labeled “XRISM Resolve Spectrum for NGC 4151.” This shows a diagram labeled “X-ray energy (keV)” at the bottom and with a range of 5 to 9. The left side is labeled “X-ray intensity.” A white wavy line starts exactly halfway on the left side. The peak value is just under 6.5 keV, almost reaching the top of the figure. After that, it starts to decrease slowly with some sharp drops around 7 keV. In the background is a faint image of the galaxy NGC 4151, whose center is whitish-blue and surrounded by red and yellow clouds. The Japanese-led XRISM (X-ray Imaging Spectroscopy Mission) began scientific operations in February and has since investigated the supermassive black hole at the center of the galaxy NGC 4151. XRISM’s Resolve instrument, a microcalorimetric spectrometer, captured a detailed spectrum of the black hole’s environment. Spikes and dips are like chemical fingerprints, allowing scientists to tell which elements are present and providing clues about the fate of matter that approaches a black hole. NGC 4151 is a spiral galaxy located approximately 43 million light-years away in the northern constellation Canis Canis. The supermassive black hole at its center has a mass more than 20 million times that of the Sun. This galaxy is also active, meaning its center is unusually bright and changeable. Gas and dust swirling toward the black hole forms an accretion disk around it, heated by gravity and frictional forces, creating fluctuations. Some of the matter at the edge of the black hole forms twin jets of particles that emerge from either side of the disk at nearly the speed of light. A fluffy donut-shaped cloud of material called a torus surrounds the accretion disk. This galaxy is unusually bright within her X-ray range, making it an ideal early target for XRISM. The decomposition spectrum of NGC 4151 shows a sharp peak at energies just below 6.5 keV (kiloelectron volts), the emission line from iron. Astronomers believe that much of the energy in active galaxies comes from X-rays emitted by hot, burning regions near black holes. X-rays reflected from the cold gas inside the disk cause the iron there to fluoresce, producing specific X-ray peaks. This allows astronomers to more accurately delineate both the disk and the eruptive region much closer to the black hole. The spectrum also shows some dips around 7 keV. Iron in the torus also caused these dips, but by absorbing X-rays rather than emitting them. This is because the material there is much cooler than the disk. All of this radiation has about 2,500 times more energy than light that our eyes can see.

Iron is just one of the elements that XRISM can detect. Depending on the source, the telescope can also detect sulfur, calcium, argon, and more. Each tells astrophysicists something different about the cosmic phenomena that litter the X-ray sky. XRISM (pronounced “crism”) is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with his NASA, with a donation from ESA (European Space Agency). It started in September. 6th, 2023. NASA and JAXA developed Resolve. Caption: This image shows the center of an active galaxy. The black hole is hidden in a bright yellow-white region at the center. It is named “Black Hole: An object with a mass 20 million times that of the Sun at the center of the galaxy.” The black hole is surrounded by yellow and orange structures. It’s described as an “accretion disk: a flat, swirling, superheated cloud of iron that emits X-rays,” embedded within a circular dark cloud. It’s labeled “Taurus: a cooler, bulging donut-shaped cloud whose iron absorbs his X-rays.” A white line runs from directly above the black hole to the top of the image. It says, “Jet: a particle beam that travels at almost the speed of light.” The scale bar that extends from the black hole to the torus says “5 light years.”

source: https://svs.gsfc.nasa.gov/14584