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Astronomers using JWST and ALMA observations have discovered that a supermassive black hole in galaxy ESO 420-G13 is expelling massive amounts of molecular and ionized gas through a previously undetected compact jet, despite the black hole having relatively low luminosity. The jet is driving powerful outflows with a total kinetic power of approximately 1.4 × 10^41 erg/s, having already expelled about 5% of the galaxy's central molecular gas reservoir. Notably, parts of the outflow are devoid of detectable carbon monoxide, likely destroyed by shocks or cosmic rays from the jet's interaction with the surrounding gas.
Why it matters
This discovery demonstrates that even low-luminosity supermassive black holes can significantly impact their host galaxies through jet-driven feedback, a process that may have remained undetected without advanced mid-infrared imaging capabilities. Understanding these feedback mechanisms is crucial for explaining how galaxies evolve and why star formation ceases in post-starburst galaxies.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: We present JWST/MIRI mid-infrared integral field spectroscopy combined with ALMA CO(2-1) observations of the post-starburst galaxy ESO 420-G13, hosting a low-luminosity AGN. The unprecedented spatial and spectral resolution of MIRI enables a detailed study of the molecular and ionised gas kinematics, excitation, and energetics in the nuclear kiloparsec, revealing the impact of AGN feedback in a system with modest radiative output. Despite its faint radio and X-ray emission ($L_{2-10keV} sim 10^{40}$ erg/s), ESO 420-G13 exhibits powerful kinetic feedback in the form of massive molecular and ionised gas outflows, with a total kinetic power of $sim 1.4 times 10^{41}$ erg/s. This corresponds to a jet-ISM coupling efficiency of ~3.8%, within the range observed in more powerful AGN. The feedback is driven by a previously undetected compact jet, traced by collimated coronal-line and extended X-ray emission to >870 pc from the nucleus. The interaction is strongest ~370 pc north of the nucleus, where a fast ionised gas stream emerges perpendicular to the jet axis, coinciding with a bend in the jet direction. Enhanced velocity dispersion in warm H$_2$ surrounds this gas stream, consistent with an expanding molecular bubble. Massive molecular outflows are detected at its edges; the blueshifted outflow is devoid of CO emission, likely due to CO destruction in shocks or by cosmic rays from the jet-ISM interaction. About 5% of the central molecular reservoir has already been expelled, and the remaining gas is turbulent and warm, suggesting an ongoing phase of AGN-driven feedback in this post-starburst galaxy. Our results highlight the enormous potential of mid-IR imaging spectroscopy to uncover jet-driven feedback in low-luminosity AGN. Without the spatially resolved MIRI diagnostics, the kinetic power of the AGN in ESO 420-G13 and its role in shaping the host galaxy ISM would have remained hidden.