Azimuthal dependence of the density distribution in outer galactic discs accreting intergalactic flows

Abstract

AIMS. The amplitude and scaleheight of the Galactic gas disc density are not axisymmetric against expectations in a self-gravity axisymmetric disc. However, this lopsidedness can be explained in terms of intergalactic accretion flows, which produce non-axisymmetric pressure on the disc. This mechanism could be also responsible for the formation of a warp. METHODS. We analytically derive the relationship between the disc density and the self-gravity and external pressure. RESULTS. The same scenario of accretion as we proposed years ago to explain the formation of the warp explains the azimuthal dependence of the density and its scaleheight, with minimum/maximum in the positions of maximum amplitude of the warp (phi=95 deg. and 275 deg.), as expected from its pressure distribution.

4 pages, accepted to be published in A&A-letters

References in corpus (8)

• Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: I. The HI Disk
• Global properties of the HI distribution in the outer Milky Way
• The Vertical Structure of the Outer Milky Way HI Disk
• Dark matter in the Milky Way, II. the HI gas distribution as a tracer of the gravitational potential
• Vertical scaleheights in a gravitationally coupled, three-component Galactic disk
• Generation of galactic disc warps due to intergalactic accretion flows onto the disc
• On the origin of warps and the role of the intergalactic medium
• Bar-driven injection of intergalactic matter into galactic halos

Cited by in corpus (4)

• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• Modeling Star counts in the Monoceros stream and the Galactic anti-centre
• Warp and flare of the Galactic disc revealed with supergiants by Gaia EDR3
• The constraining effect of gas and the dark matter halo on the vertical stellar distribution of the Milky Way