MIDIS: Unveiling the star formation history in massive galaxies at 1  <  z  <  4.5 with spectro-photometric analysis

¹ Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850 Madrid, Spain
² Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800 9700 AV Groningen, The Netherlands
³ European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁴ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA
⁵ Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
⁶ Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
⁷ Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden
⁸ DTU Space, Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
⁹ Cosmic Dawn Center (DAWN), Denmark
¹⁰ DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155A, 2200 Copenhagen, Denmark
¹¹ Centro de Astrobiología (CAB), CSIC-INTA, Camino Bajo del 1166 Castillo s/n, E-28692 Villanueva de la Cañada, Madrid, Spain
¹² I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
¹³ Leiden Observatory, Leiden University, P.O. Box 9513 2300 RA Leiden, The Netherlands
¹⁴ European Space Agency, Space Telescope Science Institute, Baltimore, Maryland, USA
¹⁵ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁶ Dept. of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
¹⁷ Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria

^⋆ Corresponding author.

Received: 4 December 2024
Accepted: 15 August 2025

Abstract

Context. This paper investigates the star formation histories (SFHs) of a sample of massive galaxies (M_⋆ ≥ 10¹⁰ M_⊙) in the redshift range 1 < z < 4.5.

Methods. We analyzed spectro-photometric data, combining broadband photometry from HST and JWST with low-resolution grism spectroscopy from JWST/NIRISS, obtained as part of the MIRI Deep Imaging Survey program. SFHs were derived through spectral energy distribution fitting using two independent codes, BAGPIPES and synthesizer, under various SFH assumptions. This approach enables a comprehensive assessment of the biases introduced by different modeling choices.

Results. The inclusion of NIRISS spectroscopy, even with its low resolution, significantly improves constraints on key physical parameters, such as the mass-weighted stellar age (t_M) and formation redshift (z_form), by narrowing their posterior distributions. The massive galaxies in our sample exhibit rapid stellar mass assembly, forming 50% of their mass between 3 ≤ z ≤ 9. The highest inferred formation redshifts are compatible with elevated star formation efficiencies (ϵ) at early epochs. Nonparametric SFHs generally imply an earlier and slower mass assembly compared to parametric forms, highlighting the sensitivity of inferred formation timescales to the chosen SFH model–particularly for galaxies at z < 2. We find that quiescent galaxies are, on average, older (t_M ∼ 1.1 Gyr) and assembled more rapidly at earlier times than their star-forming counterparts. These findings support the “downsizing” scenario, in which more massive and passive systems form earlier and more efficiently.