Cosmic Necklace Reveals Secrets of Galaxy Birth ⚡ экспресс
For the protocluster SPT2349-56 at z=4.3, multi-cycle ALMA observations were conducted in the dust continuum and [CII]158 μm line. In a 60 kpc region around the central triple system, a structured gas reservoir was discovered with a luminosity L_[CII]=3.0±0.2×10^9 L_⊙ and cold gas mass M_gas=8.9±0.7×10^9 M_⊙. Newly discovered [CII] streamers fragment into turbulent clumps a few kpc in size with surface densities of 20–60 M_⊙ pc^{−2}, comparable to the spiral arms of modern galaxies. At a dust temperature of 30 K, these clumps carry ≳3% of the total IR luminosity, yielding an exceptionally low mass-to-light ratio α_[CII]=2.95±0.3 M_⊙ L_⊙^{−1}, indicating shock heating of the molecular gas. In phase space, about half of the protocluster core galaxies lie on the same caustic as the streamers (r/r_vir×|Δv|/σ_vir≈0.1), suggesting angular momentum dissipation through tidal ejection during the assembly of the brightest cluster galaxy (BCG). The results confirm that the ejection of [CII]-bright material after multiple major mergers is an important step in the co-evolution of the BCG and hot metal-enriched atmospheres at z≳4.
Three giant galaxies collide, and from the impact, gas flies away. But it does not disappear without a trace — it compresses into clumps resembling beads of a cosmic necklace, strung on an invisible thread spanning thousands of light-years. The light from these beads comes from atoms of carbon heated by shock waves — like the air in front of a supersonic jet, only on a galactic scale.
It's amazing that the gas remains colder than ice on Earth (minus 243°C), but glows due to intense heating from the collision. In this necklace, stars are born at a furious rate: thousands of new suns appear each year, while our Milky Way creates just a couple. Spectroscopy — breaking light into colors — allows us to peer into these processes, and observations are conducted at wavelengths where cold cosmic dust and gas shine.
Such a cataclysm is not chaos, but construction: from these beads, giant elliptical galaxies later form, the most massive in the Universe.
🎯 The gas 'beads' are heated only to -243°C — 20 degrees colder than Pluto's surface. But thanks to shock waves, they glow so brightly that they can be detected at a distance of billions of light-years.