We present a new model of the extragalactic background light (EBL) and corresponding γγ opacity for intergalactic gamma-ray absorption from z = 0 up to z = 10, based on a semi-analytical model of hierarchical galaxy formation that reproduces key observed properties of galaxies at various redshifts. Including the potential contribution from Population III stars and following the cosmic reionization history in a simplified way, the model is also broadly consistent with available data concerning reionization, particularly the Thomson scattering optical depth constraints from WMAP. In comparison with previous EBL studies up to z ∼ 3-5, our predicted γγ opacity is in general agreement for observed gamma-ray energy below 400/(1 + z) GeV, whereas it is a factor of ∼ 2 lower above this energy because of a correspondingly lower cosmic star formation rate, even though the observed UV luminosity is well reproduced by virtue of our improved treatment of dust obscuration and direct estimation of star formation rate. The horizon energy at which the gamma-ray opacity is unity does not evolve strongly beyond z ∼ 4 and approaches ∼ 20 GeV. The contribution of Population III stars is a minor fraction of the EBL at z = 0, and is also difficult to distinguish through gamma-ray absorption in high-z objects, even at the highest levels allowed by the WMAP constraints. Nevertheless, the attenuation due to Population II stars should be observable in high-z gamma-ray sources by telescopes such as Fermi or CTA and provide a valuable probe of the evolving EBL in the rest-frame UV. The detailed results of our model are publicly available in numerical form at the URL http://www.slac.stanford.edu/%7eyinoue/Download.html.

We report the results of 1 ′ .5 × 3 ′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S 1.1 mm = 0.7 − 6.4 mJy (L IR ∼ 10 12.1 − 10 13.1 L ⊙ ) are at z = 3.08 − 3.10. Not only are these SMGs members of the protocluster but they in fact reside within the node at the junction of the 50 Mpc-scale filamentary three-dimensional structure traced by Lyman-α emitters (LAEs) in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 M ⊙ yr −1 Mpc −3 in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host a X-ray luminous active galactic nuclei (AGN). Our results suggest that the vigorous star formation activity and the growth of super massive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyman-α blobs (LABs), implying that the two populations coexist in high density environments for a few cases.

We present the evolution of dark matter halos in six large cosmological N-body simulations, called the ν 2 GC (New Numerical Galaxy Catalog) simulations on the basis of the ΛCDM cosmology consistent with observational results obtained by the Planck satellite. The largest simulation consists of 8192 3 (550 billion) dark matter particles in a box of 1.12 h −1 Gpc (a mass resolution of 2.20 × 10 8 h −1 M ⊙ ). Among simulations utilizing boxes larger than 1 h −1 Gpc, our simulation yields the highest resolution simulation that has ever been achieved. A ν 2 GC simulation with the smallest box consists of eight billions particles in a box of 70h −1 Mpc (a mass resolution of 3.44 × 10 6 h −1 M ⊙ ). These simulations can follow the evolution of halos over masses of eight orders of magnitude, from small dwarf galaxies to massive clusters. Using the unprecedentedly high resolution and powerful statistics of the ν 2 GC simulations, we provide statistical results of the halo mass function, mass accretion rate, formation redshift, and merger statistics, and present accurate fitting functions for the Planck cosmology. By combining the ν 2 GC simulations with our new semi-analytic galaxy formation model, we are able to prepare mock catalogs of galaxies and active galactic nuclei, which will be made publicly available in the near future.

We present a new theoretical calculation of the contribution to the extragalactic gamma-ray background radiation (EGRB) from star-forming galaxies, based on a state-of-the-art model of hierarchical galaxy formation that is in quantitative agreement with a variety of observations of local and high-redshift galaxies. Gamma-ray luminosity (L γ ) and spectrum of galaxies are related to star formation rate (ψ), gas mass (M gas ), and star formation mode (quiescent or starburst) of model galaxies using latest observed data of nearby galaxies. We try the two limiting cases about gamma-ray production: the escape limit (L γ ∝ ψM gas ) and the calorimetric limit (L γ ∝ ψ), and our standard model predicts 7 and 4% contribution from star-forming galaxies to the total EGRB flux (including bright resolved sources) recently reported by the Fermi Gamma-Ray Space Telescope. Systematic uncertainties do not allow us to determine the EGRB flux better than by a factor of ∼ 2. The predicted number of nearby galaxies detectable by Fermi is consistent with the observation. Intergalactic absorption by pair-production attenuates the EGRB flux only by a modest factor of ∼1.3 at the highest Fermi energy band, and the reprocessed cascade emission does not significantly alter EGRB at lower photon energies. The sum of the known contributions from AGNs and star-forming galaxies can explain a large part of EGRB, with a remarkable agreement between the predicted model spectrum and observation.

We present a first joint analysis of the power spectra of the thermal Sunyaev-Zeldovich (tSZ) effect measured by the Planck and the number density fluctuations of galaxies in the 2MASS redshift survey (2MRS) catalog, including their cross-correlation. Combining these measurements with the cosmic microwave background (CMB) data and CMB lensing of Planck assuming a flat ΛCDM model, we constrain the mass bias parameter asthe Planck cluster mass should be 35% lower than the true mass. The mass bias determined by the 2MRS-tSZ cross-power spectrum alone is consistent with that determined by the tSZ auto-power spectrum alone, suggesting that this large mass bias is not due to obvious systematics in the tSZ data. We find that the 2MRS-tSZ cross-power spectrum is more sensitive to less massive halos than the tSZ auto-power spectrum and it significantly improves a constraint on the mass dependence of the mass bias. The redshift dependence is not strongly constrained since the multipole range in which high redshift clusters mainly contribute to the tSZ auto is dominated by the contaminating sources. We conclude that no strong mass or redshift evolution of the mass bias is needed to explain the data.