Abstract
Abstract We study the two-dimensional (2D) line-of-sight velocity (V los) field of the low-inclination, late-type galaxy VV304a. The resulting 2D kinematic map reveals a global, coherent, and extended perturbation that is likely associated with a recent interaction with the massive companion VV304b. We use multiband imaging and a suite of test-particle simulations to quantify the plausible strength of in-plane flows due to nonaxisymmetric perturbations and show that the observed velocity flows are much too large to be driven either by a spiral structure or by a bar. We use fully cosmological hydrodynamical simulations to characterize the contribution from in- and off-plane velocity flows to the V los field of recently interacting galaxy pairs like the VV304 system. We show that, for recently perturbed low-inclination galactic disks, the structure of the residual velocity field, after subtraction of an axisymmetric rotation model, can be dominated by vertical flows. Our results indicate that the V los perturbations in VV304a are consistent with a corrugation pattern. Its V los map suggests the presence of a structure similar to the Monoceros ring seen in the Milky Way. Our study highlights the possibility of addressing important questions regarding the nature and origin of vertical perturbations by measuring the line-of-sight velocities in low-inclination nearby galaxies.
Highlights
Over the last decade a significant number of observational studies have provided strong evidence of an oscillating vertical asymmetry in our own Galactic disc (e.g. Widrow et al 2012; Xu et al 2015)
VV304a can be considered a Milky Way analogue which is currently interacting with a massive companion, VV304b
After subtracting an axisymmetric kinematic model from the observed Vlos field, we find that the residuals show strong, global and coherent motions which are consistent with a corrugation pattern
Summary
Over the last decade a significant number of observational studies have provided strong evidence of an oscillating vertical asymmetry in our own Galactic disc (e.g. Widrow et al 2012; Xu et al 2015). Over the last decade a significant number of observational studies have provided strong evidence of an oscillating vertical asymmetry in our own Galactic disc Well-known features observed in the Milky Way, such as the Monoceros Ring (Newberg et al 2002; Yanny et al 2003), the TriAnd clouds (Price-Whelan et al 2015), and the recently discovered A13 overdensity (Sheffield et al 2018), can be naturally accounted for by this asymmetry, best described as a corrugation pattern (Laporte et al 2018b). We present a full 2D kinematic map of a Milky Waytype galaxy, namely VV304a, that shows a global, coherent and extended perturbation consistent with a corrugation pattern, likely associated with the recent interaction with its massive companion, VV304b
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