Outflows in a super-Eddington quasar drive clumpy circumgalactic medium and extended Hα nebulae at z ≳ 6
Abstract
The discovery of gargantuan black holes with masses exceeding a billion solar masses at z≳6 suggests rapid black hole growth and significant energy input into their host galaxies in the early Universe. With JWST probing previously unseen phases of the interstellar (ISM) and circumgalactic (CGM) medium around z > 6 quasars, detailed theoretical studies can now be directly confronted with observations. We use zoom-in simulations of a massive protocluster at z∼6, employing both the fiducial FABLE galaxy formation model and modifications that allow earlier black hole seeding and mildly super-Eddington accretion. The central quasar remains Compton-thick throughout most of its evolution, with the obscuration arising from the ISM of its compact host galaxy. The onset of sufficiently strong quasar feedback drives a 'blow-out' episode, clearing out escape channels for ionizing radiation and leaving the central engine unobscured. This leads to a complete transformation of the CGM, whereby powerful, metal-enriched outflows produce a population of cold, fast, neutral clumps, significantly increasing the covering fraction of neutral hydrogen in the host halo. Radiative transfer calculations performed with a new ray-tracing code show that the CGM responds to quasar activity through the formation of Hα nebulae, whose size and luminosity increase with the strength of quasar feedback and decrease with obscuration level. Enhanced early black hole growth thus fundamentally reshapes the ISM and CGM of z∼6 quasars, leaving clear observable signatures in their obscuration, neutral hydrogen distribution, and extended Hα emission.
Versions
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BibTeX
@misc{tortora2026outflows,
title = {{Outflows in a super-Eddington quasar drive clumpy circumgalactic medium and extended H$α$ nebulae at $z \gtrsim 6$}},
author = {Lucas Tortora and Tiago Costa and Debora Sijacki and Jake S. Bennett},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.21719},
eprint = {2607.21719},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.21719},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Outflows in a super-Eddington quasar drive clumpy circumgalactic medium and extended Hα nebulae at z ≳ 6
AU - Lucas Tortora
AU - Tiago Costa
AU - Debora Sijacki
AU - Jake S. Bennett
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2607.21719
UR - https://arxiv.org/abs/2607.21719
AB - The discovery of gargantuan black holes with masses exceeding a billion solar masses at z≳6 suggests rapid black hole growth and significant energy input into their host galaxies in the early Universe. With JWST probing previously unseen phases of the interstellar (ISM) and circumgalactic (CGM) medium around z > 6 quasars, detailed theoretical studies can now be directly confronted with observations. We use zoom-in simulations of a massive protocluster at z∼6, employing both the fiducial FABLE galaxy formation model and modifications that allow earlier black hole seeding and mildly super-Eddington accretion. The central quasar remains Compton-thick throughout most of its evolution, with the obscuration arising from the ISM of its compact host galaxy. The onset of sufficiently strong quasar feedback drives a 'blow-out' episode, clearing out escape channels for ionizing radiation and leaving the central engine unobscured. This leads to a complete transformation of the CGM, whereby powerful, metal-enriched outflows produce a population of cold, fast, neutral clumps, significantly increasing the covering fraction of neutral hydrogen in the host halo. Radiative transfer calculations performed with a new ray-tracing code show that the CGM responds to quasar activity through the formation of Hα nebulae, whose size and luminosity increase with the strength of quasar feedback and decrease with obscuration level. Enhanced early black hole growth thus fundamentally reshapes the ISM and CGM of z∼6 quasars, leaving clear observable signatures in their obscuration, neutral hydrogen distribution, and extended Hα emission.
ER -