Photometric Properties of the Most Massive High‐Redshift Galaxies

Abstract

We calculate the observable properties of the most massive high-redshiftgalaxies in the hierarchical formation scenario where stellar spheroidand supermassive black hole growth are fueled by gas-rich mergers.Combining high-resolution hydrodynamical simulations of the hierarchicalformation of a z~6 quasar, stellar population synthesis models, templateactive galactic nucleus (AGN) spectra, prescriptions for interstellarand intergalactic absorption, and the response of modern telescopes, thephotometric evolution of galaxies destined to host z~6 quasars ismodeled at redshifts z~4-14. These massive galaxies, with enormousstellar masses of M_{*}~10^{11.5}-10^{12}M_{solar} and star formation rates ofSFR~10^{3}-10^{4} M_{solar} yr^{-1} atz{\gt}~7, satisfy a variety of photometric selection criteria based onLyman break techniques, including V-band dropouts at z{\gt}~5, i-banddropouts at z{\gt}~6, and z-band dropouts at z{\gt}~7. The observabilityof the most massive high-redshift galaxies is assessed and compared witha wide range of existing and proposed photometric surveys, including theSloan Digital Sky Survey (SDSS), Great Observatories Origins Deep Survey(GOODS)/Hubble Ultra Deep Field (HUDF), National Optical AstronomyObservatory Deep Wide-Field Survey (NDWFS), UKIRT Infared Deep SkySurvey (UKIDSS), Infrared Array Camera (IRAC) Shallow Survey, UltradeepVisible and Infrared Survey Telescope for Astronomy (VISTA), DarkUniverse Explorer (DUNE), Panoramic Survey Telescope and Rapid ResponseSystem (Pan-STARRS), Large Synoptic Survey Telescope (LSST), andSupernova/Acceleration Probe (SNAP). Massive stellar spheroids descendedfrom z~6 quasars will likely be detected at z~4 by existing surveys, butowing to their low number densities the discovery of quasar progenitorgalaxies at z{\gt}7 will likely require future surveys of large portionsof the sky ({\gt}~0.5%) at wavelengths {λ}{\gt}~1 {μ}m. Thedetection of rare, starbursting, massive galaxies at redshifts z{\gt}~6would provide support for the hierarchical formation of the earliestquasars and characterize the primitive star formation histories of themost luminous elliptical galaxies.