Proposal number: 31252 PI last name: Shidatsu Title: EXPLORING THE STRUCTURE AND ACCELERATION OF THE INNERMOST X-RAY JETS IN THE MICROQUASAR SS 433 Abstract: We propose a 230 ks XRISM observation of SS 433 at a jet precession phase when the jet is most closely aligned toward us, covering a full eclipse by the companion star and adjacent non-eclipse phases. This will resolve Doppler-shifted, ionized emission lines from the jets, as well as the neutral Fe Kalpha line from the disk or disk wind, and trace their phase-dependent variations. We also request simultaneous NuSTAR observations (20 ks in eclipse and 20 ks out of eclipse) to constrain the maximum plasma temperature of the X-ray emitting jet and separate the reflection component. Our goals are to constrain the jet acceleration site, determine the jet structure through eclipse mapping, measure orbital modulation using the FeI Kalpha line, and determine metal abundances with high precision.
Proposal number: 32042 PI last name: Fukumura Title: CLUMPY OR SMOOTH? FIRST DETAILED FE K UFO DIAGNOSTICS OF SUB-EDDINGTON QUASAR: PG1114+445 Abstract: We propose a joint observation (150ks XRISM + 80ks NuSTAR) of a type 1 nearby quasar, PG1114+445. This is a sub-Eddington AGN, for which a diverse class of X-ray outflows have been robustly detected (i.e. warm absorbers and low ionization soft band UFOs) except for Fe K UFO. In this program, XRISM will fully characterize its Fe K counterpart suggested from a systematic XMM archival search at CCD resolution. XRISM will unveil the presence of expected Fe K UFO and whether it consists of multiple UFO components, thereby probing its sub-structure as clearly revealed by Resolve in near/super-Eddington AGNs (PDS456&PG1211+143). This program will inform us of a detailed Fe K UFO profile in sub-Eddington regime, for the first time, and how it compares to that of near/super-Eddington counterparts.
Proposal number: 32175 PI last name: Mori Title: HOW DO FAST ACCRETION DISK WINDS AND HOT CORONAE DRIVE EXTREME PARTICLE ACCELERATION IN PEVATRON MICROQUASARS? Abstract: Microquasars are a new class of Galactic PeVatrons accelerating particles to PeV energies during episodic outbursts. We propose XRISM and NuSTAR observations of an X-ray outburst from one of five PeVatron microquasars, including two super-PeVatrons detected above ~1 PeV, to investigate particle acceleration via wind-driven shocks and magnetic reconnection. Resolve will identify Fe lines from high-speed disk winds and measure their bulk and turbulence velocities, while NuSTAR will characterize coronal spectra. Xtend will search for diffuse X-ray emission from ejected particles. This program launches the first time-domain, high-resolution X-ray spectroscopic study of PeVatron microquasars, interpreted by GRMHD and PIC simulations, probing their particle acceleration mechanisms most robustly.
Proposal number: 32180 PI last name: McCollough Title: EXPLORING THE RELATIVISTIC JET IN THE PEVATRON MICROBLAZAR CYG X-3 WITH XRISM Abstract: XRISM has observed Cyg X-3 in a hypersoft state (jet turned off). The spectrum revealed a feature rich spectrum. The Fe line region showed emission features related to the compact object and absorption features related to the Wolf-Rayet companion. In this proposal we propose a XRISM observation be made during a major radio flare when a powerful jet is present and gamma-ray emission is observed. Recent LHAASO observations have detect PeV emission during the major flares. XRISM/Resolve will allows us to resolve the fine structure of the absorption/emission lines and place constraints on their origin during the presence of a powerful relativistic jet and at a time of gamma-ray production.
Proposal number: 32213 PI last name: Nowak Title: THE `UNSUAL' SOFT STATE OF LMC X-1: DUAL CORONAL ATMOSPHERES, WINDS, AND IMPLICATIONS FOR ITS BLACK HOLE SPIN
Abstract: LMC X-1 is `unusual' for a soft spectrum black hole candidate in that it shows a complex relationship between modeled disk temperature and flux. This may be attributable to a warm, moderately thick atmosphere Comptonizing the underlying disk emission, before subsequently being Componized by a more tenous, hot coronal atmosphere. If true, this alters continuum estimates of its black hole spin. Furthermore, Chandra-HETG provides evidence of narrow line emission and absorption, which might complicate broad line estimates of spin. We seek to address these issues with joint XRISM/NuSTAR observations of this complex soft state black hole candidate.
Proposal number: 32226 PI last name: Weaver Title: THE JET-FEEDBACK CONNECTION AND STRATIFICATION IN NGC 1052 Abstract: We will use XRISM jointly with NuSTAR and the VLA to study the LINER NGC 1052 to investigate the critical gap in the AGN life cycle where accretion becomes less efficient. This will be ground-breaking because, to date, little work has been done for LINERs, likely the most common type of AGN in the local universe - to spectrally-constrain the relationships between the innermost regions of these AGN - the accretion disk, winds, jet, torus, and other feedback processes. NGC 1052 is excellent for this study as a LINER which crucially contains a variable radio jet that is impacting its ~edge-on torus. NGC 1052 is vital to XRISM's legacy - being an ideal target to measure torus properties, intrinsic geometry, accretion properties, and search for wind signatures.
Proposal number: 34015 PI last name: Diaz_Trigo Title: A STUDY OF THE ACCRETION DISC FLOWS DURING THE HARD STATE IN THE NEUTRON STAR X-RAY BINARY EXO 0748-676
Abstract: The dipping, eclipsing and bursting low-mass X-ray binary EXO 0748-676 awakened in June 2024 after 16 years of quiescence. In May 2025 the return to quiescence of the source was observed with Chandra. XRISM cannot miss the opportunity to observe the source if it rebrightnens during XRISM AO3. Should this happen, we propose to trigger an observation with XRISM for a total exposure time of 100 ks. We will investigate the stratification of the plasmas in the accretion disc via the presence of absorption lines from the warm and hot phases. We will then infer the structure of the disc atmosphere and of the corona with phase-resolved spectroscopy and investigate the presence of an outflow.
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