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Title: Cosmic Galaxy-IGM H i Relation at z ∼ 2–3 Probed in the COSMOS/UltraVISTA 1.6 Deg{sup 2} Field

Abstract

We present spatial correlations of galaxies and IGM neutral hydrogen H i in the COSMOS/UltraVISTA 1.62 deg{sup 2} field. Our data consist of 13,415 photo-z galaxies at z ∼ 2–3 with K{sub s}<23.4 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 {sub gal} in an impact parameter of 2.5 (proper) Mpc, and calculate the Lyα forest fluctuations δ{sub 〈F〉} whose negative values correspond to the strong Lyα forest absorption lines. We identify weak evidence of an anti-correlation between δ {sub gal} and δ{sub 〈F〉} 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 {sub obs}, B {sub obs}, C {sub obs}, and D {sub obs}, that have extremely large (small) values of δ {sub gal} ≃ 0.8 (−1) and δ{sub 〈F〉}≃0.1(−0.4), three of which, B {sub obs}–D {sub obs}, significantly depart from the δ {sub gal}–δ{sub 〈F〉} correlation,more » and weaken the correlation signal. We perform cosmological hydrodynamical simulations and compare with our observational results. Our simulations reproduce the δ {sub gal}–δ{sub 〈F〉} correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of A {sub obs}–D {sub 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 {sub obs}–D {sub obs} are produced by the filamentary large-scale structures and the observation sightline effects.« less

Authors:
; ; ;  [1];  [2];  [3];  [4];  [5];  [6];  [7]
  1. Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan)
  2. Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
  3. Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8583 (Japan)
  4. UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
  5. College of General Education, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka 574-8530 (Japan)
  6. Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States)
  7. National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)
Publication Date:
OSTI Identifier:
22869499
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DENSITY; GALACTIC EVOLUTION; GALAXIES; HYDROGEN; IMPACT PARAMETER; INTERGALACTIC SPACE; QUASARS; SPECTRA; UNIVERSE

Citation Formats

Mukae, Shiro, Ouchi, Masami, Ono, Yoshiaki, Shibuya, Takatoshi, Kakiichi, Koki, Suzuki, Nao, Cai, Zheng, Inoue, Akio K., Chiang, Yi-Kuan, and Matsuda, Yuichi. Cosmic Galaxy-IGM H i Relation at z ∼ 2–3 Probed in the COSMOS/UltraVISTA 1.6 Deg{sup 2} Field. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/281.
Mukae, Shiro, Ouchi, Masami, Ono, Yoshiaki, Shibuya, Takatoshi, Kakiichi, Koki, Suzuki, Nao, Cai, Zheng, Inoue, Akio K., Chiang, Yi-Kuan, & Matsuda, Yuichi. Cosmic Galaxy-IGM H i Relation at z ∼ 2–3 Probed in the COSMOS/UltraVISTA 1.6 Deg{sup 2} Field. United States. https://doi.org/10.3847/1538-4357/835/2/281
Mukae, Shiro, Ouchi, Masami, Ono, Yoshiaki, Shibuya, Takatoshi, Kakiichi, Koki, Suzuki, Nao, Cai, Zheng, Inoue, Akio K., Chiang, Yi-Kuan, and Matsuda, Yuichi. 2017. "Cosmic Galaxy-IGM H i Relation at z ∼ 2–3 Probed in the COSMOS/UltraVISTA 1.6 Deg{sup 2} Field". United States. https://doi.org/10.3847/1538-4357/835/2/281.
@article{osti_22869499,
title = {Cosmic Galaxy-IGM H i Relation at z ∼ 2–3 Probed in the COSMOS/UltraVISTA 1.6 Deg{sup 2} Field},
author = {Mukae, Shiro and Ouchi, Masami and Ono, Yoshiaki and Shibuya, Takatoshi and Kakiichi, Koki and Suzuki, Nao and Cai, Zheng and Inoue, Akio K. and Chiang, Yi-Kuan and Matsuda, Yuichi},
abstractNote = {We present spatial correlations of galaxies and IGM neutral hydrogen H i in the COSMOS/UltraVISTA 1.62 deg{sup 2} field. Our data consist of 13,415 photo-z galaxies at z ∼ 2–3 with K{sub s}<23.4 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 {sub gal} in an impact parameter of 2.5 (proper) Mpc, and calculate the Lyα forest fluctuations δ{sub 〈F〉} whose negative values correspond to the strong Lyα forest absorption lines. We identify weak evidence of an anti-correlation between δ {sub gal} and δ{sub 〈F〉} 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 {sub obs}, B {sub obs}, C {sub obs}, and D {sub obs}, that have extremely large (small) values of δ {sub gal} ≃ 0.8 (−1) and δ{sub 〈F〉}≃0.1(−0.4), three of which, B {sub obs}–D {sub obs}, significantly depart from the δ {sub gal}–δ{sub 〈F〉} correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations and compare with our observational results. Our simulations reproduce the δ {sub gal}–δ{sub 〈F〉} correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of A {sub obs}–D {sub 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 {sub obs}–D {sub obs} are produced by the filamentary large-scale structures and the observation sightline effects.},
doi = {10.3847/1538-4357/835/2/281},
url = {https://www.osti.gov/biblio/22869499}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 835,
place = {United States},
year = {2017},
month = {2}
}