Spectroscopic confirmation of two luminous galaxies at a redshift of 14

Area of Science:

• Cosmology
• Galaxy Evolution
• Observational Astronomy

Background:

• James Webb Space Telescope (JWST) observations have identified numerous high-redshift galaxies (z ≈ 13), suggesting rapid galaxy development.
• Many of these early galaxy candidates lack spectroscopic confirmation, leaving their distances and properties uncertain.
• This presents a potential tension with standard cosmological models regarding early galaxy formation.

Purpose of the Study:

• To provide spectroscopic confirmation for luminous galaxies at high redshifts.
• To accurately determine the distances and properties of these early galaxies.
• To test whether early luminous galaxies can be explained by black hole accretion or stellar emission.

Main Methods:

• Utilized the JWST Advanced Deep Extragalactic Survey (JW-ADES) with the Near-Infrared Spectrograph (NIRSpec).
• Obtained spectra of two candidate luminous galaxies at z ≈ 13.
• Analyzed spectral features, including ultraviolet continua and Lyman-α breaks, to confirm redshift and properties.

Main Results:

• Spectroscopic confirmation of two luminous galaxies at z = 13.90 ± 0.17.
• Galaxies exhibit ultraviolet continua with Lyman-α breaks but no emission lines.
• The most distant galaxy is unexpectedly luminous and spatially resolved (radius 260 parsecs).
• Both galaxies show steep ultraviolet slopes, indicating dominance by stellar continuum emission.

Conclusions:

• Luminous galaxies were present and well-established 300 million years after the Big Bang.
• The abundance of these early luminous galaxies exceeds previous expectations.
• The observed properties suggest stellar emission, not black hole accretion, dominates these early galaxies.
• Galaxy formation models require revision to accommodate such massive and luminous galaxies in the early Universe.