Poster Presentation

Dust enrichment in the circum-galactic medium

Author(s): Mau Otsuki (Hiroshima University), Hiroyuki Hirashita (ASIAA)

Presenter: Mau Otsuki (Hiroshima University)

Dust in the circum-galactic medium (CGM) could cause systematic reddening of background sources and play an important role in gas heating and cooling. To understand the origin and evolution of dust in the CGM, we develop a dust enrichment model. We describe each of the central galaxy and its CGM as a single zone, and consider the mass exchange between them through galactic inflows and outflows. We calculate the evolution of the gas, metal, and dust masses in the galaxy and the CGM. In the galaxy, we include stellar dust production and interstellar dust processing. The dust in the galaxy is transported to the CGM via galactic outflows, and is further processed by dust destruction (sputtering) in the CGM. We parameterize the time-scale or efficiency of each process and investigate the effect on the dust abundance in the CGM. We find that the resulting dust mass is sensitive to the dust destruction in the CGM, and the dust supply from galactic outflows, both of which directly regulate the dust abundance in the CGM. The inflow time-scale also affects the dust abundance in the CGM because it determines the gas mass evolution (thus, the star formation history) in the galaxy. The dust abundance in the CGM, however, is insensitive to stellar dust formation in the galaxy at later epochs because the dust production is dominated by dust growth in the interstellar medium. We also find that the resulting dust mass in the CGM is consistent with the value derived from a large sample of SDSS galaxies.
(This project started as a summer student project at ASIAA in 2021.)