FOREVER22: Gas and metal outflow from massive galaxies in protocluster regions

Harada, Naoki,   Yajima, Hidenobu,   & Abe, Makito

要旨

We study gas and metal outflow from massive galaxies in protocluster regions at z = 3 - 9 by using the results of FOREVER22 simulation projects. Our simulations contain massive haloes with M_hrsim10¹³ M_⊙, showing high star formation rates of > 100 M_⊙ yr^-1 and hosting supermassive black holes with M_BHrsim10⁸ M_⊙. We show that the mass loading factor (η_M) sensitively depends on the halo mass and it is η_M = 1.2 (9.2) for M_h = 10¹³ (10¹¹) M_⊙. Once the halo mass exceeds ~ 10^12.5 M_⊙, the outflow velocity of the gas rapidly decreases near a virial radius, and the gas returns to a galactic centre finally as a fountain flow. Also, the metal inflow and outflow rates sensitively depend on the halo mass and redshift. At z = 3, the inflow rate becomes larger than the outflow one if M_hrsim10^13.0 M_⊙. Thus, we suggest that massive haloes cannot be efficient metal enrichment sources beyond virial radii that will be probed in future observations, e.g., studies of metal absorption lines with the Prime Focus Spectrograph on the Subaru telescope.