The structure of the relativistic Fe line in GX 340+0 as viewed with XRISM/Resolve, NICER, and NuSTAR
Creators
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1.
Wayne State University
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University of Maryland, College Park
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3.
Goddard Space Flight Center
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Harvard-Smithsonian Center for Astrophysics
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Netherlands Institute for Space Research
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University of Michigan–Ann Arbor
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Institute of Space and Astronautical Science
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8.
Tokyo City University
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Massachusetts Institute of Technology
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10.
Hiroshima University
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Durham University
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12.
California Institute of Technology
Abstract
We present a 152 ks XRISM/Resolve observation of the persistently accreting Z source GX 3400. Simultaneous observations also occurred with NuSTAR and NICER for 22.47 ks and 2.7 ks, respectively. The source covered the normal branch to the flaring branching during the observations. The data from all three missions were modeled concurrently for each spectral branch. The superior energy resolution of XRISM/Resolve reveals structure within the iron emission line complex regardless of spectral state. We model the reprocessed Fe K line with a reflection model tailored for thermal illumination of the accretion disk by a neutron star. The currently available model encompasses the broad components, but narrow emission features remain at the ~5% level. These remaining features may be described by the presence of an ionized plasma in the system as has been observed in the Z source Cygnus X-2, but subsequent updates to the reflection model code may be able to explain these features.
Copyright and License
Acknowledgement
We thank the referee(s) for their comments that have helped to strengthen and clarify the results presented in this paper. We thank Jeremy Hare (NASA/GSFC) for helpful discussion regarding the cross calibration of NICER with NuSTAR. R.M.L. thanks Jon M. Miller (University of Michigan) for discussion of spectral modeling of XRISM/Resolve data. We acknowledge informative discussion of the XRISM calibration with Tahir Yaqoob (UMBC) and Misaki Mizumoto (University of Teacher Education Fukuoka). This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Space Science Data Center (SSDC, Italy) and the California Institute of Technology (Caltech, USA).
Funding
R.M.L. acknowledges support by NASA under award number 80NSSC23K0635. R.B. acknowledges support by NASA under award number 80GSFC21M0002. L.C. acknowledges support from NASA grants 80NSSC18K0978, 80NSSC20K0883, and 80NSSC25K7064. I.P. is supported by NASA through the Smithsonian Astrophysical Observatory (SAO) contract SV3-73016 to MIT for Support of the Chandra X-Ray Center (CXC) and Science Instruments. CXC is operated by SAO for and on behalf of NASA under contract NAS8-03060. T.N. acknowledges the support by JSPS KAKENHI Grant Numbers 23H05441 and 23K17695.
Data Availability
The NICER and NuSTAR data underlying this article are publicly available on the NASA data archive. The XRISM data are subject to a 12 months proprietary time from the completion of the XRISM Performance Verification phase data collection after which the data will be publicly available from NASA and JAXA online data archives.
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2507.06289 (arXiv)
Funding
- National Aeronautics and Space Administration
- 80NSSC23K0635
- National Aeronautics and Space Administration
- 80GSFC21M0002
- National Aeronautics and Space Administration
- 80NSSC18K0978
- National Aeronautics and Space Administration
- 80NSSC20K0883
- National Aeronautics and Space Administration
- 80NSSC25K7064
- Smithsonian Astrophysical Observatory
- SV3-73016
- National Aeronautics and Space Administration
- NAS8-03060
- Japan Society for the Promotion of Science
- 23H05441
- Japan Society for the Promotion of Science
- 23K17695
Dates
- Submitted
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2025-03-25
- Accepted
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2025-07-08
- Available
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2025-08-11Published online