Galaxies as they were.
Cosmic noon — redshift 1 to 3 — is when most of the stellar mass in the present-day universe was assembled. CELESTE resolves these formative epochs with unprecedented spatial clarity.
Imagery · ESO
Key Science Topic
Galaxy formation
Galaxy formation
& evolution.
Resolving individual star-forming complexes at cosmic noon — the visible-light counterpart to JWST's infrared picture of early galaxy assembly.
At twelve-milliarcsecond resolution, CELESTE resolves individual star-forming complexes at redshifts beyond z = 2 — the rest-frame ultraviolet morphology of galaxies during cosmic noon. This is the visible-light counterpart to JWST's infrared imaging, completing the spectral picture of early galaxy assembly.
Resolved color maps separate stellar populations within distant galaxies, distinguishing in-situ star formation from accreted satellites. Combined with deep JWST imaging and ELT spectroscopy, CELESTE data provides the morphological calibration needed to interpret the next generation of galaxy-formation surveys.
The Brief
i.
Science Objectives
Map the rest-frame UV morphology of galaxies at z = 1 – 4 at sub-kiloparsec resolution. Separate star-forming clumps from the diffuse disk. Measure size–mass and morphology–environment relations during the epoch of peak cosmic star-formation rate density.
ii.
Observables & Measurements
High-resolution imaging in the R, I, z, and Y bands, probing rest-frame UV at target redshifts. Multi-epoch imaging for resolved color maps of stellar populations. Deep fields overlapping with existing JWST JADES, CEERS, and COSMOS-Web mosaics.
iii.
Key Functional Requirements
Angular resolution ≤ 15 mas to resolve < 100 pc structures at z = 2. Stable PSF across multi-hour integrations for accurate morphological decomposition. Multi-band photometry for rest-frame UV color maps.
iv.
CELESTE Uniqueness
Hubble achieves ~50 mas in the visible — CELESTE's 12 mas resolution is four times sharper, resolving structures four times smaller at any given redshift. Ground AO cannot achieve the diffraction limit in the visible without a space-borne guide star. CELESTE is the only near-term path to this capability.