Dr Anwesh Majumder was awarded his Bachelors (2014-2017) and Masters in Physics (2017-2019) with astro specialisation from Presidency University, Kolkata, India. After that, he moved to University of Amsterdam for his PhD (2019-2025). Anwesh followed that up with a short Scientist C position at Space Research Organisation Netherlands (March 2025-May 2025) before moving to Waterloo to take up a joint position with the WCA and Brian McNamara.
Anwesh uses the XRISM X-ray telescope to understand how supermassive black holes affect the environment of galaxy clusters. XRISM provides us with a unique opportunity to study X-ray emission from gas using high-resolution spectroscopy, which allows us to study gas motion of few hundred km/s for the first time. XRISM will enable us to study the turbulent mode of energy injection by the central black hole. Anwesh routinely uses Chandra and XMM-Newton telescope data in hos work as well. He plans to expand his research horizon by working with optical and radio data during his time at the WCA.
Title: AGN Feedback and the Gentle Stirring of Cluster Cores: New Results from XRISM
Abstract: Feedback from active galactic nuclei (AGN) is a ubiquitous process in modern astrophysics that shapes environments from kpc to Mpc scales. In this talk, I will focus specifically on the effect of feedback on galaxy clusters. While it is known that the energy injection from AGNs is usually sufficient to offset cooling of the intracluster medium (ICM), the energy partition among the dominant injection mechanisms remains under active research. Over the last 25 years, major X-ray observatories such as Chandra and XMM-Newton have explored mechanisms including shocks, sound waves, and bubbles blown by AGN jets. The effect of another pathway, turbulence, has remained underexplored, as it is expected to produce gas motions of only a few hundred km/s—beyond the spectral capability of previous generations of telescopes.
The recently launched XRISM telescope has now allowed us to measure gas motions down to ~50 km/s across numerous galaxy clusters and thereby better assess the impact of AGN feedback. Surprisingly, gas motions near cluster cores are typically below 200 km/s, with only a few exceptions. This result carries important implications for energy balance in cluster cores, depending on the timescales over which this energy was injected. In my talk, I will briefly review the history of the field before discussing in detail recent advances with XRISM and their implications for energy balance in cluster cores.