A central question in galaxy evolution is whether red quasars represent a transitional phase on the way to unobscured quasars. In scenarios of intense gas inflows, star formation and the growth of an Accretion disk are triggered in systems deeply embedded in cosmic dust — such as interstellar medium (as in ultraluminous infrared galaxies, ULIRGs). Feedback from the growing black hole can subsequently expel or redistribute the surrounding gas and dust, opening sightlines to the nucleus. However, directly identifying this stage requires simultaneous constraints on the visible nucleus, dust-reprocessed emission, dense gas along the line of sight, and multiscale outflows — a dataset rarely available for a single source.
Using JWST (NIRSpec, NIRCam, MIRI), spectroscopy from MUSE, X-ray data from Chandra, millimeter observations from ALMA, and radio interferometry from VLA, astronomers obtained a detailed multiwavelength portrait of The Chick. redshift z=3.711 was determined from optical emission lines. Spectral modeling revealed broad permitted lines, dense gas absorption, and multicomponent outflows. Two-component photometry helped estimate parameters of the host galaxy and black hole.
Despite significant absorption, broad Balmer lines and X-ray emission ($L_X$ ~ 1.7×$10^{44}$ erg/s) prove that the nucleus is already partly visible. Line analysis using the Doppler effect yielded velocities: Hα absorption (redshifted +475 km/s) and HeI (blueshifted –310 km/s) indicate dense gas along the line of sight; broad OI λ8446 line shifted +700 km/s; and multiphase interstellar medium outflows — ionized ([OIII], about –290 km/s) and cold (MgII, NaD, about –280 km/s). The outflow mass is estimated at ~37 M☉/yr. ALMA detected strong cosmic dust emission with a dust mass of ~5×$10^7$ M☉ and a total infrared luminosity $L_{IR}$ ~ 3.4×$10^{12}$ L☉, corresponding to a star formation rate of ~300 M☉/yr. Dust continuum modeling, based on Planck's law and Wien's displacement law, gave a dust temperature of ~35 K. The black hole–to–host galaxy mass ratio (~0.01) exceeds the local value but does not reach the most extreme high-redshift AGNs. An extended Lyα halo (up to 20 kpc) with a velocity dispersion of ~670 km/s shows that disturbed gas extends far beyond the nucleus.
This discovery confirms that red quasars can be a brief stage when the Accretion disk has already emerged from the fully obscured phase but cosmic dust and interstellar medium have not yet completely dissipated. The simultaneous detection of a visible nucleus, dense gas absorption, and powerful outflows directly links AGN feedback with the clearing of the environment. Systematic searches for similar objects will allow estimation of the duration of this transitional phase and its role in galactic evolution.
Future observations with higher spectral resolution (e.g., JWST/NIRSpec in high-resolution mode) will allow a more detailed study of the kinematics of the multiphase gas. Wide-field surveys with new instruments, such as the upcoming Wide Field Spectrograph, will help identify statistically significant samples and determine how often such 'hatching' quasars appear. Numerical simulations that include AGN feedback can clarify exactly how the black hole's radiation and winds clear the path from a dense cocoon to an open nucleus.
The study addresses key questions of black hole growth and galaxy evolution, clarifying the link between AGN feedback and star formation rates. The multiphase outflows observed in The Chick provide direct evidence for the mechanism that regulates the coexistence of an active nucleus and a star-forming galaxy.
Plans include measuring polarization to constrain the geometry of the scattering medium and obtaining deeper X-ray spectra to assess the level of soft X-ray absorption. Additionally, searches for similar objects will be conducted in other JWST deep fields.
The nature of the red continuum in such objects remains unsolved: we need to understand the role of extreme extinction curves from small dust grains, radiation reprocessing in dense gas, or BAL-type outflows. This connects to the broader problem of quasar evolution — how supermassive black holes grow in tandem with their galaxies and how feedback regulates that growth.
This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.
What the work does
This work presents a multi-frequency analysis of a red quasar at z=3.7, combining data from JWST, ALMA, Chandra, VLA, and MUSE to simultaneously constrain the properties of the nucleus, dust emission, dense gas, and multi-scale outflows. The authors show that the source is in a transitional phase: broad lines and X-ray emission indicate a partially exposed nucleus, while significant absorption and powerful outflows suggest ongoing clearing of the cocoon.
Where its strength is
The strength of the work lies in the rare combination of observational data that captures a key moment in evolution: the accreting black hole is already visible, but feedback is still actively redistributing surrounding gas and dust. This provides direct observational constraints on the transition scenario from a fully obscured phase to an unobscured quasar.
Where it could go next
Worth trying
Why this may matter
Such objects are direct evidence of how accretion feedback regulates black hole growth and star formation in the early Universe. A detailed understanding of this phase is important for building a coherent picture of the co-evolution of galaxies and their central nuclei at z>3.
Nearby works in our archive
The closest work in the archive sits at 0.62 by meaning — the usual level for our corpus.
The Chick got its name because its spectrum resembles a hatching chick — its bright nucleus is already breaking through a shell of dust and gas. Amusingly, neighboring galaxies at distances of 12 and 66 thousand light-years may be 'members of the same nest' — possibly a protocluster at z=3.7.