JWST and ALMA Expose Deadly Galactic Winds in the Universe’s Youth

Researchers have identified powerful winds capable of halting star formation in galaxies during the universe’s infancy, offering new insight into why massive galaxies cease forming stars much earlier than anticipated. Utilizing the James Webb Space Telescope (JWST) alongside the Atacama Large Millimeter/submillimeter Array (ALMA), scientists detected an enormous outflow of gas escaping from a galaxy merely one billion years after the Big Bang. This discovery gives concrete proof of a mechanism likely instrumental in shaping early galaxy evolution. The findings appear in today’s issue of the Monthly Notices of the Royal Astronomical Society.

Galaxy Mergers Ignite Intense Cosmic Winds

In the early cosmos, galaxies were densely packed, experiencing frequent collisions which fueled rapid star formation. Such chaotic environments directed gas towards galactic centers, sparking prolific stellar births that subsequently drove fierce winds.

“Dense regions of the universe are like very active cities,” said lead author Dr. Rebecca Davies of Swinburne University of Technology in Melbourne, who conducted the study with Associate Professor Deanne Fisher. “Galaxies collide and undergo frenzied bursts of star formation. But when the biggest stars burn out, they explode as supernovas, launching powerful winds that blast away the very gas galaxies need to keep forming stars.”

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These winds act as a cosmic scavenger, driving out the gas required to fuel the creation of new stars. Studies of the galaxy cluster CRISTAL-02, currently engaged in a multigalactic collision, reveal this effect dramatically: a stream of cold gas nearly as extensive as the galaxy itself marks a swift depletion of star-forming material.

Composite imaging of CRISTAL-02 by JWST and ALMA. (i) A 4 arcsec × 3 arcsec 3-color composite from JWST/NIRCam showing marked star-forming clusters (a–d) and a dim companion (e), with contours representing [C II] λ158 μm flux at 4σ, 7σ, 10σ, and 15σ, highlighting a plume northeast of Clump b. Aperture locations for spectral extraction are shown with dashed magenta and cyan circles. The grey ellipses indicate the observational point spread function. (ii) Ionized gas velocity dispersion derived from single-component fitting and corrected for instrumental effects, with contours depicting broad, blueshifted [C II] emission between −500 and −150 km s⁻¹ at 3σ and 5σ levels, forming a biconical outflow structure along the NE–SW axis. The dotted line marks the kinematic major axis (PA = 127°), while the dashed line indicates the outflow direction (PA = 60°). (iii) Diagram illustrating the outflow geometry, originating from Clump b. (iv)–(vi) Surface density maps of star formation rate from H α, and [C II] moment 1 (velocity offset) and moment 2 (velocity spread). (vii) Velocity profiles for [C II] (black) and H α (orange) emissions along the outflow path, showing increasing blueshift from Clump b toward the [C II] plume. Credit: Monthly Notices of the Royal Astronomical Society.

CRISTAL-02 Offers a Glimpse into Early Galaxy Demise

CRISTAL-02 is an extraordinary assembly of colliding galaxies, exhibiting a star formation rate twice that of typical galaxies its size. Through JWST and ALMA’s advanced capabilities, astronomers captured massive gaseous outflows streaming from the system, illustrating the severity of the galactic winds responsible for shutting down star formation.

“The galaxy has a powerful wind that is ejecting material twice as fast as the galaxy forms stars,” Dr. Davies explained. “If this rapid blowout continues, the galaxy could be dead in less than 50 million years, explaining the origin of the mysterious massive dead galaxies in the early universe.”

This direct observation confirms the theory that early galaxies burned through their star-making fuel quickly and then rapidly ceased star formation, resolving a puzzle that has challenged astronomers for years.

Relations between galaxy metrics and their outflow characteristics. Left: The outflow mass loading factor versus stellar mass for 99 star-driven outflows spanning 12 billion years, including measurements of ionized phases and total outflows in galaxies with multiphase data. Best-fit linear relations at z ∼ 0 (blue) and between 2 and 5.5 (pink) are shown with associated uncertainties. CRISTAL-02 exhibits outflow traits comparable to similarly massive galaxies at lower redshifts, with no clear temporal evolution of the mass-loading factor. Right: Outflow velocity (top) and ionized outflow mass flux (bottom) compared against star formation rate surface density (Σ_SFR). Filled grey contours depict data from 500 pc regions in starburst galaxies near z ∼ 0, with best-fit lines and scatter shown. Two CRISTAL-02 mass flux estimates are displayed: one from Clump b and another assuming a 500 pc outflow radius for z ∼ 0 comparison. CRISTAL-02 follows velocity and mass trends like lower redshift outflows but with much higher Σ_SFR, providing key tests for supernova-driven wind models. Credit: Monthly Notices of the Royal Astronomical Society.

Broad Impact on Models of Galaxy Lifecycles

The results, featured in Monthly Notices of the Royal Astronomical Society, indicate that such galaxy-quenching winds were not rare but prevalent throughout the early cosmos. Nearly half of the massive galaxies from that era appear to be interacting with other galaxies, suggesting that collisions and accelerated star formation were typical occurrences.

“Almost half of early massive galaxies are interacting with other nearby galaxies, suggesting this isn’t a quirk but a widespread cosmic phenomenon,” Dr. Davies added. “If many early galaxies collide and experience rapid growth, then it may not be surprising that we see so many dead galaxies in the early universe. CRISTAL-02 offers a natural solution to the mystery of why these massive galaxies live fast and die young.”

This research enriches our comprehension of how galaxies formed and evolved during the universe’s formative epochs, shedding light on the life cycles of its earliest massive systems.

Revolutionizing Our View of the Early Universe

The study highlights the groundbreaking role of JWST and ALMA in unlocking secrets from the cosmos’s first billion years. By observing phenomena such as galaxy-terminating winds, astronomers can trace how primordial galaxies flourished through collisions, only to rapidly fade. These findings are reshaping our cosmic timeline and refining theoretical models to better capture the violent origins and swift ends of early galactic giants.

CRISTAL-02’s story exemplifies the fleeting but spectacular nature of the universe’s initial massive galaxies, which burned bright before succumbing to their own powerful winds.