Examinando por Autor "Cooper, M.C"

Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    An Extremely Massive Quiescent Galaxy at z = 3.493: Evidence of Insufficiently Rapid Quenching Mechanisms in Theoretical Models
    (Institute of Physics Publishing, 2020-02) Forrest, Ben; Annunziatella, Marianna; Wilson, Gillian; Marchesini, Danilo; Muzzin, Adam; Cooper, M.C; Marsan, Cemile; McConachie, Ian; C. C. Chan, Jeffrey; Gomez, Percy; Kado-Fong, Erin; La Barbera, Francesco; Labbé, Ivo; Daniel, Langle -Vagle; Julie, Nantais; Nonino, Mario; Peña, Theodore; Saracco, Paolo; Mauro, Stefanon; Remco van der Burg, F.J
    We present spectra of the most massive quiescent galaxy yet spectroscopically confirmed at z > 3, verified via the detection of Balmer absorption features in the H- A nd K-bands of Keck/MOSFIRE. The spectra confirm a galaxy with no significant ongoing star formation, consistent with the lack of rest-frame UV flux and overall photometric spectral energy distribution. With a stellar mass of 3.1-0.2-+0.1× 10-11\,M at z = 3.493, this galaxy is nearly three times more massive than the highest redshift spectroscopically confirmed absorption-line-identified galaxy known. The star formation history of this quiescent galaxy implies that it formed >1000 M o yr-1 for almost 0.5 Gyr beginning at z ∼ 7.2, strongly suggestive that it is the descendant of massive dusty star-forming galaxies at 5 < z < 7 recently observed with ALMA. While galaxies with similarly extreme stellar masses are reproduced in some simulations at early times, such a lack of ongoing star formation is not seen there. This suggests the need for a quenching process that either starts earlier or is more rapid than that currently prescribed, challenging our current understanding of how ultra-massive galaxies form and evolve in the early universe. © 2020. The American Astronomical Society. All rights reserved.
  • Miniatura
    Ítem
    The GOGREEN and GCLASS surveys: First data release
    (Oxford University Press, 2021-01) Balogh, Michael L; van der Burg, Remco F.J; Muzzin, , Adam; Rudnick, , Gregory; Wilson, , Gillian; Webb, , Kristi; Biviano, , Andrea; Boak, , Kevin; Cerulo, , Pierluigi; Chan, , Jeffreyf; Cooper, M.C; Gilbank, , David G
    We present the first public data release of the GOGREEN (Gemini Observations of Galaxies in Rich Early Environments) and GCLASS (Gemini CLuster Astrophysics Spectroscopic Survey) surveys of galaxies in dense environments, spanning a redshift range 0.8 < z < 1.5. The surveys consist of deep, multiwavelength photometry and extensive Gemini GMOS spectroscopy of galaxies in 26 overdense systems ranging in halo mass from small groups to the most massive clusters. The objective of both projects was primarily to understand how the evolution of galaxies is affected by their environment, and to determine the physical processes that lead to the quenching of star formation. There was an emphasis on obtaining unbiased spectroscopy over a wide stellar mass range (M ≿ 2 × 1010 M☉), throughout and beyond the cluster virialized regions. The final spectroscopic sample includes 2771 unique objects, of which 2257 have reliable spectroscopic redshifts. Of these, 1704 have redshifts in the range 0.8 < z < 1.5, and nearly 800 are confirmed cluster members. Imaging spans the full optical and near-infrared wavelength range, at depths comparable to the UltraVISTA survey, and includes Hubble Space Telescope/Wide Field Camera 3 F160W (GOGREEN) and F140W (GCLASS). This data release includes fully reduced images and spectra, with catalogues of advanced data products including redshifts, line strengths, star formation rates, stellar masses, and rest-frame colours. Here, we present an overview of the data, including an analysis of the spectroscopic completeness and redshift quality. © 2020 The Author(s).