Photometric properties of the most massive high-redshift galaxies

We calculate the observable properties of the most massive high-redshift galaxies in the hierarchical formation scenario where stellar spheroid and supermassive black hole growth are fueled by gas-rich mergers. Combining high-resolution hydrodynamical simulations of the hierarchical formation of a z ∼ 6 quasar, stellar population synthesis models, template active galactic nucleus (AGN) spectra, prescriptions for interstellar and intergalactic absorption, and the response of modern telescopes, the photometric evolution of galaxies destined to host z ∼ 6 quasars is modeled at redshifts z ∼ 4-14. These massive galaxies, with enormous stellar masses of M ∼ 10 ^11.5-10¹² M_⊙ and star formation rates of SFR ∼ 10³-10⁴ M_⊙ yr^-1 at z ≳ 7, satisfy a variety of photometric selection criteria based on Lyman break techniques, including V-band dropouts at z ≳ 5, i-band dropouts at z ≳ 6, and z-band dropouts at z ≳ 7. The observability of the most massive high-redshift galaxies is assessed and compared with a wide range of existing and proposed photometric surveys, including the Sloan Digital Sky Survey (SDSS), Great Observatories Origins Deep Survey (GOODS)/Hubble Ultra Deep Field (HUDF), National Optical Astronomy Observatory Deep Wide-Field Survey (NDWFS), UKIRT Infared Deep Sky Survey (UKIDSS), Infrared Array Camera (IRAC) Shallow Survey, Ultradeep Visible and Infrared Survey Telescope for Astronomy (VISTA), Dark Universe Explorer (DUNE), Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), Large Synoptic Survey Telescope (LSST), and Supernova/Acceleration Probe (SNAP). Massive stellar spheroids descended from z ∼ 6 quasars will likely be detected at z ∼ 4 by existing surveys, but owing to their low number densities the discovery of quasar progenitor galaxies at z > 7 will likely require future surveys of large portions of the sky (≳0.5%) at wavelengths λ ≳ 1 μm. The detection of rare, starbursting, massive galaxies at redshifts z ≳ 6 would provide support for the hierarchical formation of the earliest quasars and characterize the primitive star formation histories of the most luminous elliptical galaxies.