NGC 4151 is a spiral galaxy located approximately 62 million light-years away in the northern constellation Hanabi.
This artist's concept shows possible locations for iron revealed in NGC 4151's XRISM X-ray spectrum. Image credit: Conceptual Image Lab, NASA's Goddard Space Flight Center.
The X-ray Imaging and Spectroscopy Mission (XRISM), a joint effort between JAXA and NASA, with extensive participation from ESA, launched from Japan's Tanegashima Space Center on September 6, 2023.
After beginning science operations in February 2024, the spacecraft focused on the supermassive black hole at the center of NGC 4151.
“XRISM's Resolve instrument captured a detailed spectrum of the region around the black hole,” said researcher Brian Williams, Ph.D., of NASA's Goddard Space Flight Center.
“The peaks and valleys are like chemical fingerprints that tell us what elements are present and can reveal clues about the fate of matter that approaches a black hole.”
NGC 4151's supermassive black hole holds more than 20 million times the mass 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 material at the edge of the black hole forms twin jets of particles that shoot out from either side of the disk at nearly the speed of light.
A bulging donut-shaped cloud of material called a torus surrounds the accretion disk.
XRISM's Resolve instrument captured data from the center of NGC 4151. The resulting spectrum reveals the presence of iron with a peak around 6.5 keV and a dip around 7 keV, thousands of times more energetic than the light visible to our eyes. Image credits: JAXA / NASA / XRISM Resolve / CXC / CfA / Wang et al. / Isaac Newton Telescope Group, La Palma Island / Jacobus Kapteyn Telescope / NSF / NRAO / VLA.
“In fact, NGC 4151 is one of the closest known active galaxies,” Dr. Williams and his colleagues said.
“Other missions, such as NASA's Chandra X-ray Observatory and the NASA/ESA Hubble Space Telescope, are conducting research to learn more about the interactions between black holes and their surroundings, allowing scientists to study galaxies. Find out how the supermassive black hole at the center of time grows throughout the universe.
“This galaxy is unusually bright in X-rays, making it an ideal early target for XRISM.”
“The NGC 4151 spectrum in Resolve shows a sharp peak at energies just below 6.5 keV, an iron emission line.”
Astronomers believe that much of the power in active galaxies comes from X-rays emanating from hot, blazing regions near black holes.
When the X-rays reflect off the cold gas inside the disk, the iron there fluoresces, producing a specific X-ray peak.
This allowed for a more accurate depiction of both the disk and the eruptive region much closer to the black hole.
“The spectrum also shows some dips around 7 keV,” the astronomers said.
“The iron present in the torus caused these dips as well, but due to absorption rather than emission of X-rays, because the material there is much cooler than in the disk.”
“All of this radiation is about 2,500 times more energetic than the light we can see with our eyes.”
“Iron is just one of the elements that XRISM can detect. The telescope can also detect sulfur, calcium, argon, and more, depending on the source.”
“Each one tells us something different about the cosmic phenomena that litter the X-ray sky.”
Source: www.sci.news
