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arXiv · 2002.07334

Connection Between Galaxies and HI in the Circumgalactic and Intergalactic Media: Variation According to Galaxy Stellar Mass and Star-formation Activity

Rieko Momose·Ikkoh Shimizu·Kentaro Nagamine·Kazuhiro Shimasaku·Nobunari Kashikawa·Haruka Kusakabe
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Abstract

This paper systematically investigates comoving Mpc 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 ($δ_\text{F}$); and (II) comparing the overdensity of neutral hydrogen (HI) and galaxies. Our simulations reproduce observed cross-correlation functions (CCF) between Ly$α$ forest and Lyman-break galaxies. We further investigate the variation of the CCF using subsamples divided by dark matter halo mass ($M_\text{DH}$), galaxy stellar mass ($M_\star$), and star-formation rate (SFR), and find that the CCF signal becomes stronger with increasing $M_\text{DH}$, $M_\star$, and SFR. The CCFs between galaxies and gas-density fluctuation are also found to have similar trends. Therefore, the variation of the $δ_\text{F}$-CCF depending on $M_\text{DH}$, $M_\star$, and SFR is due to varying gas density around galaxies. We find that the correlation between galaxies and the IGM HI distribution strongly depends on $M_\text{DH}$ as expected from the linear theory. Our results support the $Λ$CDM paradigm, finding a spatial correlation between galaxies and IGM HI, with more massive galaxies being clustered in higher-density regions.

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Rieko Momose, Ikkoh Shimizu, Kentaro Nagamine, Kazuhiro Shimasaku, Nobunari Kashikawa, Haruka Kusakabe. 2021-03-08. Connection Between Galaxies and HI in the Circumgalactic and Intergalactic Media: Variation According to Galaxy Stellar Mass and Star-formation Activity. https://doi.org/10.3847/1538-4357%2Fabe1b9

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