NOAO >   Observing Info >   Approved Programs >   2013A-0228

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Proposal Information for 2013A-0228


PI: Danilo Marchesini, Tufts University, danilo.marchesini@tufts.edu
Address: Physics Department, 4 Colby Street, Medford, MA 02155, USA

CoI: Adam Muzzin, Leiden Observatory
CoI: Pieter van Dokkum, Yale University
CoI: David Wake, Yale University
CoI: Marijn Franx, Leiden Observatory
CoI: Cemile Marsan, Tufts University
CoI: Gregory Rudnick, Kansas University
CoI: Mauro Stefanon, Missouri University
CoI: Gabriel Brammer, European Southern Observatory
CoI: Britt Lundgren, Yale University
CoI: Katherine Whitaker, NASA/GSFC
CoI: Tomer Tal, UC-Santa Cruz
CoI: Ryan Quadri, Carnegie Observatories
CoI: Ivo Labbe, Leiden Observatory
CoI: Rachel Bezanson, Yale University

Title: Revealing the Monsters: GNIRS Spectroscopy of Ultra-Massive Galaxies at 1.5<z<3.0

Abstract: One of the most controversial questions regarding the formation and evolution of galaxies is when and how the most massive galaxies formed. Recent deep NIR surveys have discovered the existence of a substantial population of massive (M_\rm star$~1- 2\times$10^11 M_\odot), quiescent, and compact galaxies at 1.5$<$z$<$3, whose mere existence presents a critical challenge to the standard hierarchical model of galaxy formation. Extrapolation of the stellar mass function suggests even more massive ``monster'' galaxies may exist at these redshifts, but their space density is much lower, similar to that of Brightest Cluster Galaxies. From the NMBS-II, our 4.75 deg^2, 44-night NOAO survey program with NEWFIRM, we have identified the first large sample of 30 ultra-massive galaxies (M_\rm star$>$4$\times$10^11M_\sun) at 1.5$<$z$<$3.0. We propose to use Gemini-GNIRS to obtain high-quality spectra of 10 objects in COSMOS to confirm their redshifts and to comprehensively characterize, for the first time, the properties (number density, star- formation and AGN activity, and gas-phase metallicity) of these ultra- massive galaxies at z$~$2.3. These observations will provide crucial information that future models will have to reproduce, accounting for the problem that the existence of a significant population of these ``monster'' galaxies poses to the standard hierarchical model.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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