Year: 2017
Type: article
Abstract: We present spatial correlations of galaxies and IGM neutral hydrogen H i in the COSMOS/UltraVISTA 1.62 deg2 field. Our data consist of 13,415 photo-z galaxies at z ∼ 2–3 with and the Lyα forest absorption lines in the background quasar spectra selected from SDSS data with no signature of damped Lyα system contamination. We estimate a galaxy overdensity δ gal in an impact parameter of 2.5 (proper) Mpc, and calculate the Lyα forest fluctuations whose negative values correspond to the strong Lyα forest absorption lines. We identify weak evidence of an anti-correlation between δ gal and with a Spearman’s rank correlation coefficient of −0.39 suggesting that the galaxy overdensities and the Lyα forest absorption lines positively correlate in space at the ∼90% confidence level. This positive correlation indicates that high-z galaxies exist around an excess of H i gas in the Lyα forest. We find four cosmic volumes, dubbed A obs, B obs, C obs, and D obs, that have extremely large (small) values of δ gal ≃ 0.8 (−1) and , three of which, B obs–D obs, significantly depart from the δ gal– correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations and compare with our observational results. Our simulations reproduce the δ gal– correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of A obs–D obs, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the quasar sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of B obs–D obs are produced by the filamentary large-scale structures and the observation sightline effects.
Source: The Astrophysical Journal
Authors: Shiro Mukae, Masami Ouchi, Koki Kakiichi, Nao Suzuki, Yoshiaki Ono, Zheng Cai, Akio K. Inoue, Yi-Kuan Chiang, Takatoshi Shibuya, Yuichi Matsuda
Institutions: Institute for Cosmic Ray Research, The University of Tokyo, Kavli Institute for the Physics and Mathematics of the Universe, Max Planck Institute for Astrophysics, University College London, University of California, Santa Cruz, Osaka Sangyo University, The University of Texas at Austin, The Graduate University for Advanced Studies, SOKENDAI, National Astronomical Observatory of Japan
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, Alfred P. Sloan Foundation, Eli Lilly and Company, Yale University, Vanderbilt University, Princeton University, Ohio State University, Harvard University, University of Washington, Johns Hopkins University, Carnegie Mellon University, University of Portsmouth, New Mexico State University, York University, Ministry of Education, Culture, Sports, Science and Technology, Office of Science, College of Engineering, Michigan State University, Japan Society for the Promotion of Science, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory
OpenAlex ID: W2346824523