The Breath of a Galactic Nucleus: Why a Cluster Doesn't Cool Down ✛

Original: "Vigorous turbulence driven by quasar-mode feedback in a cluster core"

· Satoshi Yamada, Shutaro Ueda, Hirofumi Noda, Yutaka Fujita, Misaki Mizumoto, Kentaro Nagamine, Claudio Ricci, Shoji Ogawa, Taiki Kawamuro, Shinya Yamada, Yuichi Terashima, Yoshihiro Ueda

arXiv:2607.24911v1 · 2026-07-27 · CC BY 4.0 · 1 min

Galaxies High Energy

The quasar (ultrabright core) at the center of cluster H1821+643 transfers up to 10% of its energy to the gas — and its 'breath' prevents the cluster from freezing.

Galaxy clusters are enormous clouds of hot gas, home to hundreds of galaxies. At the center of one of them, H1821+643, shines a quasar — a supermassive black hole devouring matter and outshining an entire galaxy. Part of that matter is expelled outward as a powerful wind. This wind stirs up the surrounding gas, like a breath into a cup of scalding hot tea.

Why does this matter? Hot gas in clusters continuously loses energy through X-ray radiation and should cool down. Once cool, it would rush toward the center, collapsing into stars. But quasar heating acts like antifreeze: it warms the medium just enough to prevent freezing.

Measurements with unprecedented precision have shown that iron ions in this cluster are flying apart at speeds of 295 km/s — 130 km/s faster than in calm regions. The quasar wind uses up to 10% of its energy to create this turbulence (chaotic vortices in the plasma). That is enough to fully offset the cooling. Thus, a mechanism that had remained theoretical for decades has received direct observational confirmation.

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H1821+643 is not only the closest quasar in a cluster to us, but also one of the most powerful: its X-ray luminosity is 10,000–100,000 times higher than that of any other quasar in a similar environment. At the same time, it is in a surprisingly 'quiet' evolutionary stage: its jets are barely noticeable, and it is classified as radio-quiet.

f_{\rm nth} = \frac{\mu m_p \sigma_v^2}{k T}

The ratio of the kinetic energy of turbulent motions to the thermal energy of the gas. μ is the mean molecular weight, m_p is the proton mass, σ_v is the line-of-sight velocity dispersion, k is the Boltzmann constant, and T is the temperature.

Scientists

Roger Penrose Margaret Burbidge Maarten Schmidt

Concepts

quasar feedback quasar black hole wind black hole feedback galactic winds accretion disk wind galactic outflow acceleration ultra fast outflow crab nebula gas cloud central engine star formation in clusters quintessence cosmic ray acceleration energy cascade quantum vortex shock wave quasi periodic eruptions outburst gravitational wave frequency

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The Breath of a Galactic Nucleus: Why a Cluster Doesn't Cool Down ✛