Multiphase Gas Offsets in the Atmospheres of Central Galaxies and Their Consequences for SMBH Activation. I. The Hot and Warm Ionized Gas Phases

Abstract We investigate the spatial relationships between multiphase gas components and supermassive black hole (SMBH) activity in a sample of 25 cool-core galaxy groups and clusters. Using high-angular-resolution observations from Chandra, the Very Large Telescope/Multi Unit Spectroscopic Explorer, and the Very Long Baseline Array (VLBA), we robustly locate the positions, respectively, of the X-ray peak of the intracluster medium, of the H α peak of the warm ionized gas, and of the SMBH radio core, on parsec scales. We identify spatial offsets between the X-ray peak of the hot gas and the SMBH in 80% of the systems, with an average displacement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>X-ray</mml:mtext> <mml:mspace width="0.1em"/> </mml:mrow> <mml:mrow> <mml:mspace width="0.1em"/> <mml:mtext>SMBH</mml:mtext> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>=</mml:mo> <mml:mn>4.8</mml:mn> </mml:math> kpc (dispersion of 3.8 kpc). In contrast, the peak of warm ionized gas traced by H α exhibits a much smaller offset ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>H</mml:mtext> <mml:mspace width="0.1em"/> <mml:mi>α</mml:mi> </mml:mrow> <mml:mrow> <mml:mspace width="0.1em"/> <mml:mtext>SMBH</mml:mtext> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>=</mml:mo> <mml:mn>0.6</mml:mn> </mml:math> kpc; dispersion of 1.4 kpc) and a lower incidence of displacement (15%). Our findings suggest that hot-gas sloshing primarily drives the observed spatial offsets, with active galactic nucleus (AGN)–driven uplift contributing in some systems. Importantly, systems with H α– SMBH offsets of ≥1 kpc uniformly lack detectable radio cores on VLBA scales, with upper limits on the 5 GHz power of P 5GHz ​​​​​ ≤ 10 21–22 W Hz −1 , while those without such offsets exhibit radio-powerful AGNs with parsec-scale radio emission up to P 5GHz ∼ 10 24–25 W Hz −1 . This correlation indicates that centrally concentrated warm gas is critical for sustaining radio-loud SMBH activity, possibly supporting scenarios of cold-mode accretion. Overall, our results highlight the importance of high-angular-resolution multiwavelength observations for understanding the interplay between multiphase gas cooling and AGN fueling in central galaxies.