Work

The MICADO first light imager for the ELT: simulated observations of star forming clumps at cosmic noon

Year: 2026

Type: article

Abstract: ABSTRACT Galaxies at redshift z $\sim$ 2–6 exhibit prominent star-forming regions (clumps). Characterization of these galactic structures requires both high sensitivity and spatial resolution of $\sim 100\,$pc or less. Currently, these spatial scales are achievable only with the aid of strong gravitational lensing. However, lensing introduces model-dependent uncertainties and limits the sample to galaxies behind massive clusters. The upcoming 40 m-class telescopes, such as the ESO Extremely Large Telescope (ELT), will enable routine studies of clumps in ubiquitous, non-lensed z$\ge$2 galaxies. We assess the capability of MICADO, the first-light imager and spectrograph of the ELT, to characterize clumps in non-lensed z = 2 galaxies. Specifically, we focus on two representative observing scenarios, providing the basis for an early scientific exploitation of the instrument. We modelled clumps in an idealized z = 2 star-forming galaxy and produced mock MICADO observations in both broad- and narrow-band imaging. The latter leverages the strong emission lines typical of clumps to improve detection and characterization. Reaching UV rest-frame magnitudes of clumps as faint as $M_{\rm UV}\sim -15$ in optimal observing conditions, MICADO will be able to efficiently characterize clumps in non-lensed z = 2 galaxies down to $R_{\rm e}$ $\sim$ 20$\,$pc. Moreover, the full MICADO $\sim 1\,$arcmin$^{2}$ field of view enables efficient surveys of multiple targets. This study demonstrates MICADO’s potential to fill a crucial observational gap, shedding new light on clump formation and evolution at cosmic noon. Accurate PSF reconstruction will be crucial to fully harness this capability as it significantly impacts clump detection and characterization, especially at the smallest sizes ($\lt 40\,$ pc).

Source: Monthly Notices of the Royal Astronomical Society

DOI: 10.1093/mnras/stag1714