A Dynamical Test for Cooling-Induced Entrainment in a Runaway Supermassive Black Hole Tail

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Autori principali: Kaul, Ish, Oh, S. Peng
Natura: Preprint
Pubblicazione: 2026
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author Kaul, Ish
Oh, S. Peng
author_facet Kaul, Ish
Oh, S. Peng
contents Radiative turbulent mixing layers are widely invoked to explain the survival, growth, and entrainment of cold gas in hot astrophysical flows, but quantitative dynamical tests have remained scarce. RBH-1, the first confirmed runaway supermassive black hole, offers a rare opportunity to test this framework: JWST observations show a 62 kpc tail of cold H$α$ and [O III]-emitting gas behind a source moving at ~950 km/s through the hot circumgalactic medium, with a coherent velocity gradient of ~200 km/s along the tail. Using 3D hydrodynamical simulations together with turbulent mixing-layer theory, we model the coherent downstream tail. We find that the observed downstream deceleration is well reproduced by accretion-induced drag from radiative mixing layers, and that without radiative cooling no coherent cold tail forms. We also derive a direct connection between the tail deceleration and the cooling luminosity, yielding predictions for future measurements of the cooling luminosity profile. RBH-1 therefore provides a rare quantitative dynamical stress test of radiative mixing-layer physics in an astrophysical system.
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id arxiv_https___arxiv_org_abs_2604_13155
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Dynamical Test for Cooling-Induced Entrainment in a Runaway Supermassive Black Hole Tail
Kaul, Ish
Oh, S. Peng
Astrophysics of Galaxies
Radiative turbulent mixing layers are widely invoked to explain the survival, growth, and entrainment of cold gas in hot astrophysical flows, but quantitative dynamical tests have remained scarce. RBH-1, the first confirmed runaway supermassive black hole, offers a rare opportunity to test this framework: JWST observations show a 62 kpc tail of cold H$α$ and [O III]-emitting gas behind a source moving at ~950 km/s through the hot circumgalactic medium, with a coherent velocity gradient of ~200 km/s along the tail. Using 3D hydrodynamical simulations together with turbulent mixing-layer theory, we model the coherent downstream tail. We find that the observed downstream deceleration is well reproduced by accretion-induced drag from radiative mixing layers, and that without radiative cooling no coherent cold tail forms. We also derive a direct connection between the tail deceleration and the cooling luminosity, yielding predictions for future measurements of the cooling luminosity profile. RBH-1 therefore provides a rare quantitative dynamical stress test of radiative mixing-layer physics in an astrophysical system.
title A Dynamical Test for Cooling-Induced Entrainment in a Runaway Supermassive Black Hole Tail
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2604.13155