@ARTICLE{2026A&A...710A.249S,
       author = {{Santini}, P. and {Castellano}, M. and {Calabr{\`o}}, A. and {Fontana}, A. and {Merlin}, E. and {Bevacqua}, D. and {Bergamini}, P. and {Boquien}, M. and {Cantarella}, S. and {Ciesla}, L. and {Ferrara}, A. and {Finkelstein}, S.~L. and {Fortuni}, F. and {Gandolfi}, G. and {Gasparetto}, T. and {Giallongo}, E. and {Grogin}, N.~A. and {Guida}, S.~T. and {Koekemoer}, A.~M. and {Menci}, N. and {Napolitano}, L. and {Paris}, D. and {Pentericci}, L. and {Perez-Diaz}, B. and {Stoyanova}, B. and {Treu}, T.},
        title = "{The early maturity of high-redshift galaxies: Insights from sSFR, M/L, and SFHs at z {\ensuremath{\sim}} 7─14}",
      journal = {\aap},
     keywords = {galaxies: evolution, galaxies: formation, galaxies: high-redshift, galaxies: star formation, galaxies: stellar content},
         year = 2026,
        month = jun,
       volume = {710},
          eid = {A249},
        pages = {A249},
     abstract = "{The James Webb Space Telescope (JWST) has revealed an unexpected excess
        of UV-bright galaxies at z > 10, unaccounted for by
        extrapolations from pre-JWST observations and theoretical
        models. Understanding the physical properties and star formation
        histories (SFHs) of high-redshift systems is key to
        distinguishing between the different proposed scenarios and
        assessing their implications for the galaxy formation and
        evolution picture. We identified and analysed a sample of 2420
        robust candidates at z {\ensuremath{\sim}} 7 {\ensuremath{-}} 14
        drawn from the ASTRODEEP-JWST dataset over
        {\ensuremath{\sim}}0.2 deg$^{2}$, and modelled their properties
        with non-parametric SFHs to derive the specific star formation
        rate (sSFR) and stellar population properties. We find that the
        median sSFR and M/L remain roughly constant across the probed
        redshift range. We show that this result is robust against
        potential systematics unless a hidden population of dust-
        enshrouded starbursts, undetectable in the current data, exists
        at these redshifts. In any case, the absence of observed high-
        sSFR systems at the highest redshifts suggests that any dust-
        free starburst phase must be short-lived. The observed sSFR
        evolution is in tension with most (though not all) theoretical
        models, making it a key quantity for discriminating among
        competing scenarios. The sample shows a wide range of physical
        conditions and galaxy classes, including systems with low sSFRs
        and high mass-to-light ratios (M/L) up to z {\ensuremath{\sim}}
        10, indicative of already-evolved galaxies only a few hundred
        megayears after the Big Bang, and different degrees of dust
        attenuation. We finally reconstructed the assembly histories of
        two sub-samples, namely the highest-M/L galaxies at z
        {\ensuremath{\sim}} 7 {\ensuremath{-}} 8, which appear to have
        formed the bulk of their stars at least 500 Myr before
        observation, implying progenitors observable as UV-bright
        sources at z > 20, and the full sample of z > 11 galaxies, which
        formed through stochastic SFHs, remaining UV-faint for most of
        their early evolution, before undergoing recent
        ({\ensuremath{\sim}}50 Myr old) episodes of major growth.}",
          doi = {10.1051/0004-6361/202558516},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2026A&A...710A.249S},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}