The Sweeping-out of Dust by Radiation Pressure of Stars and Chemical Composition Peculiarities of Disc Galaxies

Abstract

Abstract— We consider the drift of dust grains of various sizes and chemical compositions caused by the stellar radiation pressure in the vicinity of the Milky Way. When integrating the equations of motion, in addition to the radiation pressure, we consider the gravitational attraction from various components of the Galaxy and the gas drag. It has been shown that carbonaceous grains of medium sizes (~0.01 μm) are swept out of the galactic disc most effectively. Smaller dust grains are swept out to a substantially lesser extent, or they are not swept out at all. We also consider the motion of silicate dust grains, including those with porous structure. It has been shown that silicate grains experience a considerably weaker impact of the radiation pressure. The simulation result of their motion does not essentially depend on whether their porosity is accounted for or ignored. The total rate of the Galaxy’s dust loss has turned out to be high—approximately 0.03 M⊙ per year, which is comparable to the effect produced by the other mechanisms ejecting heavy elements to the circumgalactic space. We discuss the potential of the sweeping of dust out of the Galaxy in formation of the radial metallicity gradient, as well as the prospects of detecting extensive dust structures in elliptical galaxies.

Dust in Clusters of Galaxies

“…A series of studies has been focused on the vertical support and transport of dust particles in optically thin low-density galactic halos. The amount of halo gas above 1-2 scale heights is only ≤ e −1 of the total column density, and correspondingly, radiation-accelerated dust particles move without transferring their momentum to gas, i.e., without a launching of galactic bulk mass outflows [17,21,[101][102][103][104][105][106]. Indirect considerations of radiation pressure as a driving mechanism of dust acceleration in the form of filaments and their substructures extending up to > ∼ 1 kpc above the plane of the NGC 891 galaxy have been obtained by Rossa et al [107].…”

“…It is important to emphasize that disentangling the actual source of momentum for driving dust out of galactic plane-large-scale shock waves versus radiation pressureis always challenging. However, as pointed out by several authors, stellar radiation can be efficient in galaxies only above ∼1 − 2 scale heights of the interstellar gas, whereas at lower heights, other mechanisms-SNe shocks and/or convection-are to be the dominant carriers of dust from the plane upwards [17,21,[104][105][106][114][115][116]. This is connected with the fact that at heights z < ∼ 1 − 2 of scale heights with a relatively high gas density, collisional coupling with the gas and a corresponding collisional drag force are large, such that the momentum from stellar radiation is insufficient.…”

Dust in Clusters of Galaxies

“…It is important to emphasize that disentangling the actual source of momentum for driving dust out of galactic plane-large-scale shock waves versus radiation pressure-is always challenging. However, as pointed out by several authors, stellar radiation can be efficient in galaxies only above ∼1 − 2 scale heights of the interstellar gas, whereas at lower heights, other mechanisms-SNe shocks and/or convection-are to be the dominant carriers of dust from the plane upwards [17,21,[104][105][106][114][115][116]. This is connected with the fact that at heights z < ∼ 1 − 2 of scale heights with a relatively high gas density, collisional coupling with the gas and a corresponding collisional drag force are large, such that the momentum from stellar radiation is insufficient.…”