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Paper: Galactic Disk Warps due to Intergalactic Accretion Flows onto the Disk
Volume: 390, Pathways Through an Eclectic Universe
Page: 359
Authors: López-Corredoira, M.; Betancort-Rijo, J.; Beckman, J.E.
Abstract: The accretion of the intergalactic medium onto the gaseous disk is used to explain the generation of galactic warps. A cup-shaped distortion is expected, due to the transmission of the linear momentum, but this effect is small for most incident inflow angles and the predominant effect turns out to be the transmission of angular momentum, i.e., a torque giving an integral-sign shaped warp. The torque produced by a flow of velocity ∼ 100 km−1 and baryon density ∼ 10−25 kgm−3, which is within the possible values for the intergalactic medium, is enough to generate the observed warps and this mechanism offers quite a plausible explanation. The inferred rate of infall of matter, ∼ 1M yr−1, to the Galactic disk that this theory predicts agrees with the quantitative predictions of chemical evolution resolving key issues, notably the G-dwarf problem.

Sánchez-Salcedo (2006) suggests that this mechanism is not plausible because it would produce a dependence of the scale height of the disk with the galactocentric azimuth in the outer disk, but rather than being an objection, this is another argument in favor of the mechanism because this dependence is actually observed in our Galaxy.

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