• Clusters of Galaxies

  

  Galaxy clusters are the largest gravitationally bound structures of our Universe. Most of the normal matter is in the form of a hot, X-ray emitting gas that exists between the individual galaxies known as the "intracluster medium." But what is the cosmic history of this medium? How does it assemble into such large scale structures? How does it get heated to extreme temperatures of tens of millions of degrees? How do outflows from supermassive black holes and cluster-cluster mergers affect its dynamics on both large and small scales? What is the chemical composition of this gas and how do clusters get enriched by stars and supernovae across cosmic times? XRISM will make detailed measurements of these objects, characterizing the temperature, chemical makeup, and motions of the hot gas in clusters, providing decisive answers to these fundamental questions and revolutionizing our understanding of the formation and the evolution of the largest structures in our Universe.

• Hot Stars

  

  Massive stars with tens of solar masses slowly lose mass through high-velocity winds, especially near the end of their lifetime. These gases include elements such as nitrogen, oxygen, and carbon, which go on to be the ingredients of future stars, planets, and even life itself. XRISM will measure the motions and elemental abundances of hot gases produced by the winds, witnessing how these stars supply essential materials to the cosmos.

• Supernova Remnants

  

  XRISM observations will be ideally suited to spatially-extended sources such as supernova remnants, whose X-ray morphology is a complex interplay between plasma in various ionization states. High spectral resolution observations will allow astronomers to disentangle the components of the emission lines resulting from the thermal properties of the hot gas with those resulting from the bulk motion of the material expanding at thousands of kilometers per second. XRISM will make detailed measurements of the abundances of various elements synthesized in the supernova, a direct probe of the mechanism of the stellar explosion.

• Starbursts

  

  A collection of stellar winds from massive stars and supernova explosions create a galaxy wind, which removes materials from the galaxy and, therefore, affects the evolution of the galaxy. But how do winds blow through galaxies? How far do winds travel? And what is the fate of hot winds? XRISM will measure the velocity of the hot winds, for the first time, to constrain the total energy of the winds driven by star formation. XRISM will also provide the metal contents of winds to trace how heavy materials are transported into intergalactic space.

• Black Holes

  

  Black holes big and small, when actively accreting matter, can launch powerful winds from their accretion disks. In the case of the supermassive black holes in centers of galaxies, these outflows can carry massive amounts of mass and energy, potentially impacting gas and stars in the host galaxy.

  XRISM is uniquely suited to answer many critical questions about the origin and destiny of such black hole winds. Thanks to Resolve's high spectral resolution in the hard X-ray band and good effective area, scientists will be able to resolve the structure of absorption lines imprinted by these outflows onto the black hole disk radiation and determine their velocities, column densities, and ionization. Furthermore, if the absorption features reveal (currently unknown) any particular shapes, they could be used to determine what force is pushing the gas away from the black hole, answering the long-standing question of whether these winds are magnetically, radiatively, or thermally driven.

• High Mass X-ray Binaries

  

  High Mass X-ray Binaries, which consist of a massive star and a compact object, provide the opportunity to study stellar winds as well as the binary mass transfer in great detail. In these systems radiation from the accretion process around the compact object is "X-raying" the wind material. The wind material that is being accreted is complex, e.g., as characterized by its geometry, its ionization structure, possible clumping, and more. With its high spectral resolution XRISM is exceptionally well suited for separating the X-ray signatures of different wind components and characterizing the binary accretion process.

XRISM Instruments

The XRISM payload consists of two instruments:

• Resolve, a soft X-ray spectrometer, which combines a lightweight Soft X-ray Telescope paired with a X-ray Calorimeter Spectrometer, and provides non-dispersive 5-7 eV energy resolution in the 0.3-12 keV bandpass with a field of view of about 3 arcmin.



• Xtend, a soft X-ray Imager, is a CCD detector with a larger field, at the focus of the second lightweights Soft X-ray Telescope in the energy range of 0.4-13 keV

Their characteristics are similar to the SXS and SXI, respectively flown on Hitomi. XRISM is designed to recover the science capability lost with the Hitomi incident, but focuses only on the soft X-ray bands.

Each instrument is combined with an identical X-ray Mirror Assembly (XMA), which houses the primary (parabolic nested foils) and secondary (hyperbolic nested foils) mirrors. Each mirror contains 4 quadrants with 203 nested mirror foil segments (1624 mirror segments in a single XMA).

NASA/GSFC develops the Resolve detector and many of its subsystems together with the Soft X-ray Telescopes. NASA/GSFC has also responsibility for the Science Data Center charter to delevelop the analysis software for all instruments, the data processing pipeline as well as to support Guest Observers and the XRISM Guest Observer Program.