Dynamics of AGN feedback in the X-ray bright eastern and southwestern “arms” of M87, mapped by XRISM

¹ SRON, Space Research Organisation Netherlands Niels Bohrweg 4 2333 CA Leiden, The Netherlands
² Leiden Observatory, Leiden University PO Box 9513 2300 RA Leiden, The Netherlands
³ Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa Chiba 277-8583, Japan
⁴ NASA / Goddard Space Flight Center Greenbelt MD 20771, USA
⁵ School of Physics & Astronomy, University of Nottingham Nottingham NG7 2RD, UK
⁶ Department of Physics, Nagoya University Aichi 464-8602, Japan
⁷ Department of Physics & Astronomy, Waterloo Centre for Astrophysics, University of Waterloo Ontario N2L 3G1, Canada
⁸ Department of Astronomy, University of Geneva Versoix CH-1290, Switzerland
⁹ Department of Astronomy, University of Maryland College Park MD 20742, USA
¹⁰ Center for Research and Exploration in Space Science and Technology, NASA / GSFC (CRESST II) Greenbelt MD 20771, USA
¹¹ Department of Astronomy and Astrophysics, University of Chicago Chicago IL 60637, USA
¹² Center for Space Sciences and Technology, University of Maryland, Baltimore County (UMBC) Baltimore MD 21250, USA
¹³ Department of Physics, Tokyo Metropolitan University Tokyo 192-0397, Japan
¹⁴ Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA) Kanagawa 252-5210, Japan
¹⁵ RIKEN Nishina Center Saitama 351-0198, Japan
¹⁶ Department of Physics, Rikkyo University Tokyo 171-8501, Japan
¹⁷ IRAP, CNRS, Université de Toulouse, CNES, UT3-UPS Toulouse, France
¹⁸ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology Cambridge MA 02139, USA
¹⁹ Department of Astrophysics and Atmospheric Sciences, Kyoto Sangyo University Kyoto 603-8555, Japan
²⁰ Yale Center for Astronomy and Astrophysics, Yale University New Haven CT 06520-8121, USA

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 5 December 2025
Accepted: 19 January 2026

Abstract

Context. Feedback from active galactic nuclei (AGN) plays a critical role in regulating gas cooling and star formation in massive galaxies and at the centers of galaxy clusters. As the central galaxy in the nearest cluster, M87 provides the best spatial resolution for disentangling the complex interactions between AGN jets and the surrounding environment.

Aims. We investigate the velocity structure of the multi-temperature X-ray gas in M87, particularly in the eastern and southwestern “arms” associated with past AGN outbursts, using high-resolution spectroscopy from XRISM/Resolve.

Methods. We analyzed a mosaic of XRISM/Resolve observations covering the core of M87, fitting single- and multi-temperature models to spectra extracted from different regions and energy bands. We assessed the line-of-sight velocities and velocity dispersions of the hotter ambient and cooler uplifted gas phases, and evaluated systematic uncertainties related to instrumental gain calibration.

Results. The hotter intracluster medium (ICM) phase, traced by Fe He-α emission, shows velocity dispersions below ∼100 km/s, and no significant velocity shifts between the arms and a relaxed offset region, suggesting limited dynamical impact from older AGN lobes. In contrast, the cooler gas phase appears to exhibit larger line-of-sight velocity gradients up to several hundred km/s as well as a higher velocity dispersion than the ambient hot phase, although these conclusions remain tentative pending improvements in the robustness of the gain calibration at lower energies.

Conclusions. The first microcalorimeter-resolved map of gas dynamics in M87 supports the uplift scenario for the X-ray arms, with the cooler gas in the east and southwest seemingly moving in opposite directions along the line-of-sight. The kinetic energy is a small fraction of the gravitational potential energy associated with the gas uplift, and XRISM further suggests that AGN-driven motions may be short-lived in the hot ambient ICM. These constraints provide important input toward shaping future models of AGN feedback.