Examinando por Autor "Hirschmann, Michaela"

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    The First Quenched Galaxies: When and How?
    (American Astronomical Society, 2024-05-01) Xie, Lizhi; De Lucia, Gabriella; Fontanot, Fabio; Hirschmann, Michaela; Bahé, Yannick M.; Balogh, Michael L.; Muzzin, Adam; Vulcani, Benedetta; Baxter, Devontae C.; Forrest, Ben; Wilson, Gillian; Rudnick, Gregory H.
    Many quiescent galaxies discovered in the early Universe by JWST raise fundamental questions on when and how these galaxies became and stayed quenched. Making use of the latest version of the semianalytic model GAEA that provides good agreement with the observed quenched fractions up to z ∼ 3, we make predictions for the expected fractions of quiescent galaxies up to z ∼ 7 and analyze the main quenching mechanism. We find that in a simulated box of 685 Mpc on a side, the first quenched massive (M ⋆ ∼ 1011 M ⊙), Milky Way-mass, and low-mass (M ⋆ ∼ 109.5 M ⊙) galaxies appear at z ∼ 4.5, z ∼ 6.2, and before z = 7, respectively. Most quenched galaxies identified at early redshifts remain quenched for more than 1 Gyr. Independently of galaxy stellar mass, the dominant quenching mechanism at high redshift is accretion disk feedback (quasar winds) from a central massive black hole, which is triggered by mergers in massive and Milky Way-mass galaxies and by disk instabilities in low-mass galaxies. Environmental stripping becomes increasingly more important at lower redshift.
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    The stellar mass function of quiescent galaxies in 2 < z < 2.5 protoclusters
    (Oxford University Press, 2024-01) Edward, Adit H.; Balogh, Michael L.; Bahe, Yannick M.; Cooper M.C.; Hatch, Nina A.; Marchioni, Justin; Muzzin, Adam; Noble, Allison; Rudnick, Gregory H; Vulcani, Benedetta; Wilson, Gillian; De Lucia, Gabriella; Demarco, Ricardo; Forrest, Ben; Hirschmann, Michaela; Castignani, Gianluca; Cerulo, Pierluigi; Finn, Rose A.; Hewitt, Guillaume; Jablonka, Pascale; Kodama, Tadayuki; Maurogordato, Sophie; Nantais, Julie; Xie, Lizhi
    We present an analysis of the galaxy stellar mass function (SMF) of 14 known protoclusters between 2.0 < z < 2.5 in the COSMOS field, down to a mass limit of 109.5 M. We use existing photometric redshifts with a statistical background subtraction, and consider star-forming and quiescent galaxies identified from (NUV - r) and (r - J) colours separately. Our fiducial sample includes galaxies within 1 Mpc of the cluster centres. The shape of the protocluster SMF of star-forming galaxies is indistinguishable from that of the general field at this redshift. Quiescent galaxies, however, show a flatter SMF than in the field, with an upturn at low mass, though this is only significant at ∼2σ. There is no strong evidence for a dominant population of quiescent galaxies at any mass, with a fraction <15 per cent at 1σ confidence for galaxies with log M∗/M < 10.5. We compare our results with a sample of galaxy groups at 1 < z < 1.5, and demonstrate that a significant amount of environmental quenching must take place between these epochs, increasing the relative abundance of high-mass () quiescent galaxies by a factor 2. However, we find that at lower masses (), no additional environmental quenching is required. © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.