Vertical distribution of stars and flaring in the Milky Way

Abstract

We study the vertical stellar distribution of the Milky Way thin disk treated as a gravitationally coupled system of stars, HI and H2 gas in the field of dark matter halo, from R = 4 to 22 kpc. We show that the gas and halo gravity mainly constrain this vertical distribution toward the mid-plane in the inner and the outer Galaxy, respectively. The halo gravity reduces the disk thickness by a factor of 3-4 in the outer Galaxy. Despite this constraining effect the disk thickness increases steadily with radius, flaring steeply beyond 17 kpc, making a flaring disk a generic result.

HI 21 cm observation and mass models of the extremely thin galaxy FGC 1440

“…Further, using the stellar and the HI surface density, along with the dark matter mass models, we solve the two-component Jeans equation for modeling the vertical stellar dispersion as a function of radius. We use the observed stellar scaleheight and the limits on the HI velocity dispersion and the HI scaleheight as constraints on the two-component Jeans equation (Narayan & Jog 2002;Banerjee et al 2010;Sarkar & Jog 2020, 2019bPatra 2020bPatra ,a, 2018.…”