Oral Presentation
Circumnuclear multi-phase gas around the central AGN in a cool-core cluster, A1644-South
Presenter: Junhyun Baek (Yonsei University)
We present the active galactic nucleus (AGN) jet and the circumnuclear multi-phase gas properties of the brightest cluster galaxy (BCG) in the center of Abell 1644-South (A1644-S). The primary goal is to investigate how the large-scale cluster cooling environment ultimately affects small-scale AGN activity at the cluster center. The sharply peaked X-ray surface brightness profile of A1644-S implies the presence of a cooling gas flow. Also, its prototypical X-ray hot gas sloshing indicates that A1644-S is in a merging system where intracluster medium (ICM) cooling has recently started. In order to probe how the flow of cooling gas fuels the central supermassive black hole and leads the AGN activities in the early stage of a cool-core cluster, we analyze the ALMA CO and CN (1-0) data, JVLA HI data, and KaVA 22 GHz data for the central region of A1644-S. Based on the spatially resolved morphology and kinematics of CO gas, we suggest a connection between the cold molecules and the hot ICM cooling. HI and CN gas is detected in absorption with an extended redshift tail, suggesting the cool gas is falling to the nucleus and then fed to the central AGN. Indeed, we find a parsec-scale bipolar jet at 22 GHz in the center of A1644-S, which implies that this AGN has been (re)triggered quite recently. Combining this, we discuss the role of circumnuclear cool gas in fueling the centrally located cluster AGN in the cool-core environment.
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