Spiral Arms and Bars Act as Galactic Fuel Pumps for Early Star Formation

• The "Cosmic Noon," occurring 2 to 3 billion years after the Big Bang, saw star formation rates (SFR) up to 100 times higher than modern levels.
• New research using JWST and the NOEMA millimeter array confirms that massive galaxies during this period were not merely chaotic/lumpy, but contained well-ordered spiral arms and bars.
• These structural features act as "galactic fuel pumps," efficiently channeling cold molecular gas from outer disks to central regions to sustain high star formation.
• Findings suggest that these ancient, ordered galaxies resemble the modern-day Milky Way, but with significantly faster gas transport mechanisms.

Research Basis

• Data stems from the NOEMA3D survey, which analyzed molecular gas kinematics in massive main-sequence galaxies at redshifts z~1.1-1.6.
• Two key papers detail the findings:
  • "Galaxy morphologies at cosmic noon with JWST: A foundation for exploring gas transport with bars and spiral arms" (Astronomy and Astrophysics), led by Dr. Juan Manuel Espejo Salcedo.
  • "NOEMA3D: Resolving radial gas flows in disk galaxies at z~1.1-1.6 with high-resolution CO observations" (arxiv.org), led by Jean-Baptiste Jolly.

Mechanisms and Implications

• Stars require dense, cold gas to collapse; heat or extreme turbulence hinders this process.
• JWST imagery and spectroscopic measurements revealed gas motion that could not be explained by rotation alone; excess movement was spatially correlated with bars and spiral arms.
• The rate of gas inflow driven by these structures matches the observed SFR, suggesting they drive both star formation and potentially feed central supermassive black holes.
• This evidence contradicts previous theories that early star-forming galaxies were primarily defined by mergers and dynamical instability.