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Published January 20, 2026 | Version Published
Journal Article Open

XRISM Finds the Changing-look Active Galactic Nucleus NGC 1365 in an Extended Low State: A Dense, Highly Ionized Outflow Obscures the Central Source

Creators

  • 1. ROR icon Massachusetts Institute of Technology
  • 2. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 3. ROR icon Technion – Israel Institute of Technology
  • 4. ROR icon University of Maryland, College Park
  • 5. ROR icon Eureka Scientific
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Institute of Space and Astronautical Science
  • 8. ROR icon Lawrence Livermore National Laboratory
  • 9. ROR icon University of Cambridge
  • 10. ROR icon Hiroshima University
  • 11. ROR icon Goddard Space Flight Center
  • 12. SRON Space Research Organization Netherland, s, Niels Bohrweg 4, 2333CA Leiden, The Netherlands
  • 13. ROR icon University of Geneva
  • 14. ROR icon University of Chicago
  • 15. ROR icon Ehime University
  • 16. ROR icon Tohoku University

Abstract

We present the first XRISM/Resolve observations of the active galactic nucleus NGC 1365, obtained in 2024 February and July. NGC 1365 is known for rapid transitions between Compton-thick and Compton-thin states, along with strong absorption from a highly ionized wind. During our observations, the source was found in a persistent low-flux state, characterized by a decrease in hard-X-ray luminosity and significant line-of-sight obscuration. In this state, XRISM/Resolve reveals clear Fe xxv and Fe xxvi absorption lines together with, for the first time in this source, corresponding emission lines. These features may arise either from reemission from a photoionized wind (P Cygni profile) or from collisionally ionized gas associated with outflow-driven shocks in the interstellar medium. We estimate the wind launch radius to be approximately 1016 cm (∼104Rg), consistent with the location of the X-ray broadline region. We also resolve a broadened Fe Kα line by σ ∼ 1300 km s−1, placing it at similar scales to the wind, consistent with radii inferred from disk-broadening models and the variability of the Fe Kα broad line. The similarity of the Fe Kα profile to the Hβ wing and broad Paα width indicates that the X-ray-emitting region is likely cospatial with the optical/infrared broadline region and originates from the same gas.

Copyright and License

© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

F.Z. and E.K. acknowledge support by NASA grant 80NSSC25K7065. P.K. acknowledges support from the NASA Hubble Fellowship grant HST-HF2-51534.001—A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. E.B. and A.J. acknowledge support from NASA grant 80NSSC25K0082. M.E. acknowledges support from the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. S.O. acknowledges support from the Japan Society for the Promotion of Science (JSPS) KAKENHI grant No. 24K17104 (S.O.). Part of this research employs a list of Chandra datasets, obtained by the Chandra X-ray Observatory, contained in 10.25574/cdc.509.

Software References

HEAsoft (Nasa High Energy Astrophysics Science Archive Research Center (Heasarc) 2014), SPEX (J. S. Kaastra et al. 1996), SAS (C. Gabriel et al. 2004), CIAO (A. Fruscione et al. 2006).

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2601.00795 (arXiv)
Is supplemented by
Dataset: 10.25574/cdc.509 (DOI)

Funding

National Aeronautics and Space Administration
80NSSC25K7065
National Aeronautics and Space Administration
HST-HF2-51534.001-A
National Aeronautics and Space Administration
NAS5-26555
National Aeronautics and Space Administration
80NSSC25K0082
United States Department of Energy
DE-AC52-07NA27344
Japan Society for the Promotion of Science
24K17104

Dates

Submitted
2025-09-24
Accepted
2025-12-19
Available
2026-01-19
Published

Caltech Custom Metadata

Caltech groups
Space Radiation Laboratory , Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published