Connection between Galaxies and H i in Circumgalactic and Intergalactic Media: Variation according to Galaxy Stellar Mass and Star Formation Activity

• Published in: The Astrophysical journal Vol. 911; no. 2; p. 98
• Main Authors: Momose, Rieko, Shimizu, Ikkoh, Nagamine, Kentaro, Shimasaku, Kazuhiro, Kashikawa, Nobunari, Kusakabe, Haruka
• Format: Journal Article
• Language: English
• Published: Philadelphia IOP Publishing 01.04.2021
• Subjects: Astrophysics; Correlation analysis; Cross correlation; Dark matter; Forests; Galaxies; Galaxy distribution; Gas density; Hydrogen; Intergalactic media; Star & galaxy formation; Star formation; Star formation rate; Stars & galaxies; Stellar mass
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abe1b9

Abstract This paper systematically investigates the comoving megaparsec-scale intergalactic medium (IGM) environment around galaxies traced by the Ly α forest. Using our cosmological hydrodynamic simulations, we investigate the IGM–galaxy connection at z = 2 by two methods: (i) cross-correlation analysis between galaxies and the fluctuation of Ly α forest transmission ( δ F ) and (ii) comparison of the overdensity of neutral hydrogen (H i ) and galaxies. Our simulations reproduce observed cross-correlation functions (CCFs) between Ly α forest and Lyman-break galaxies. We further investigate the variation of the CCF using subsamples divided by dark matter halo mass ( M DH ), galaxy stellar mass ( M ⋆ ), and star formation rate (SFR) and find that the CCF signal becomes stronger with increasing M DH , M ⋆ , and SFR. The CCFs between galaxies and gas density fluctuation are also found to have similar trends. Therefore, the variation of δ F –CCF depending on M DH , M ⋆ , and SFR is due to varying gas densities around galaxies. We find that the correlation between galaxies and the IGM H i distribution strongly depends on M DH as expected from linear theory. Our results support the ΛCDM paradigm, confirming a spatial correlation between galaxies and IGM H i , with more massive galaxies being clustered in higher-density regions.