Delving into the depths of NGC 3783 with XRISM

II. Cross-calibration of X-ray instruments used in the large, multi-mission observational campaign

¹ Department of Astronomy, University of Geneva, Versoix 1290, Switzerland
² Department of Physics, Ehime University, Ehime 790-8577, Japan
³ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
⁴ NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁵ Center for Research and Exploration in Space Science and Technology, NASA/GSFC (CRESST II), Greenbelt, MD 20771, USA
⁶ Department of Physics, University of Tokyo, Tokyo 113-0033, Japan
⁷ Department of Physics, Technion, Technion City, Haifa 3200003, Israel
⁸ Center for Space Sciences and Technology, University of Maryland, Baltimore County (UMBC), Baltimore, MD 21250 USA
⁹ Center for Astrophysics | Harvard-Smithsonian, MA 02138, USA
¹⁰ Lawrence Livermore National Laboratory, CA 94550, USA
¹¹ Department of Astronomy, University of Michigan, MI 48109, USA
¹² SRON Netherlands Institute for Space Research, Leiden, The Netherlands
¹³ ESO, Karl-Schwarzschild-Strasse 2, 85748, Garching bei München, Germany
¹⁴ Centre for Extragalactic Astronomy, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
¹⁵ Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Kanagawa 252-5210, Japan
¹⁶ Department of Economics, Kumamoto Gakuen University, Kumamoto 862-8680 Japan
¹⁷ Department of Physics, Kyoto University, Kyoto 606-8502, Japan
¹⁸ Department of Physics, Tokyo Metropolitan University, Tokyo 1920397, Japan
¹⁹ Department of Physics, Hiroshima University, Hiroshima 739-8526, Japan
²⁰ Department of Physics, Fujita Health University, Aichi 470-1192, Japan
²¹ Department of Astronomy and Physics, Saint Mary’s University, Nova Scotia B3H 3C3, Canada
²² California Institute of Technology, Pasadena, CA 91125, USA
²³ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), 2200 AG Noordwijk, The Netherlands
²⁴ Faculty of Engineering, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki, Miyazaki 889-2192, Japan
²⁵ RIKEN Nishina Center, Saitama 351-0198, Japan
²⁶ Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA, Leiden, The Netherlands
²⁷ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, MA 02139, USA
²⁸ Department of Physics, Saitama University, Saitama 338-8570, Japan
²⁹ Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
³⁰ Faculty of Physics, Tokyo University of Science, Tokyo 162-8601, Japan
³¹ Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
³² Department of Electronic Information Systems, Shibaura Institute of Technology, Saitama 337-8570, Japan
³³ Department of Earth and Space Science, Osaka University, Osaka 560-0043, Japan
³⁴ Department of Physics, University of Wisconsin, WI 53706, USA
³⁵ Department of Physics & Astronomy, Waterloo Centre for Astrophysics, University of Waterloo, Ontario N2L 3G1, Canada
³⁶ Department of Physics, Nagoya University, Aichi 464-8602, Japan
³⁷ Science Research Education Unit, University of Teacher Education Fukuoka, Fukuoka 811-4192, Japan
³⁸ Hiroshima Astrophysical Science Center, Hiroshima University, Hiroshima 739-8526, Japan
³⁹ Department of Data Science, Tohoku Gakuin University, Miyagi 984-8588, Japan
⁴⁰ College of Science and Engineering, Kanto Gakuin University, Kanagawa 236-8501, Japan
⁴¹ European Space Agency(ESA), European Space Astronomy Centre (ESAC), 28692 Madrid, Spain
⁴² Department of Science, Faculty of Science and Engineering, KINDAI University, Osaka 577-8502, Japan
⁴³ Department of Teacher Training and School Education, Nara University of Education, Nara 630-8528, Japan
⁴⁴ Astronomical Institute, Tohoku University, Miyagi 980-8578, Japan
⁴⁵ Department of Physics, Nara Women’s University, Nara 630-8506, Japan
⁴⁶ Department of Astrophysics and Atmospheric Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
⁴⁷ School of Science and Technology, Meiji University, Kanagawa, 214-8571, Japan
⁴⁸ Yale Center for Astronomy and Astrophysics, Yale University, CT 06520-8121, USA
⁴⁹ Department of Physics, Konan University, Hyogo 658-8501, Japan
⁵⁰ Graduate School of Science and Engineering, Kagoshima University, Kagoshima, 890-8580, Japan
⁵¹ Department of Physics, Chuo University, Tokyo 112-8551, Japan
⁵² Faculty of Education, Shizuoka University, Shizuoka 422-8529, Japan
⁵³ Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan
⁵⁴ Nihon Fukushi University, Shizuoka 422-8529, Japan
⁵⁵ Anton Pannekoek Institute, the University of Amsterdam, Postbus 942491090 GE Amsterdam, The Netherlands
⁵⁶ RIKEN Cluster for Pioneering Research, Saitama 351-0198, Japan
⁵⁷ Department of Physics, Faculty of Science, Nara Women’s University, Nara 630-8506, Japan
⁵⁸ Johns Hopkins University, MD 21218, USA
⁵⁹ Department of Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Ave, Chicago, IL 60637, USA
⁶⁰ Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22807, USA
⁶¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

^★ Corresponding author: j.s.kaastra@sron.nl

Received: 17 June 2025
Accepted: 16 July 2025

Abstract

Context. Accurate X-ray spectroscopic measurements are fundamental for deriving basic physical parameters of the most abundant baryon components in the Universe. The plethora of X-ray observatories currently operational enables a panchromatic view of the high-energy emission of celestial sources. However, uncertainties in the energy-dependent calibration of the instrument transfer functions (e.g. the effective area, energy redistribution, or gain) can limit - and historically, did limit - the accuracy of X-ray spectroscopic measurements.

Aims. We revised the status of the cross-calibration among the scientific payload on board four operation missions: Chandra, NuSTAR, XMM-Newton, and the recently launched XRISM. XRISM carries the micro-calorimeter Resolve, which yields the best energy resolution at energies ≥2 keV. For this purpose, we used the data from a 10-day-long observational campaign targeting the nearby active galactic nucleus NGC 3783, carried out in July 2024.

Methods. We present a novel model-independent method for assessing the cross-calibration status that is based on a multi-node spline of the spectra with the highest-resolving power (XRISM/Resolve in our campaign). We also estimated the impact of the intrinsic variability of NGC 3783 on the cross-calibration status due to the different time coverages of participating observatories and performed an empirical reassessment of the Resolve throughput at low energies.

Results. Based on this analysis, we derived a set of energy-dependent correction factors of the observed responses, enabling a statistically robust analysis of the whole spectral dataset. They will be employed in subsequent papers describing the astrophysical results of the campaign.