The Pisces Plume and the Magellanic Wake

Abstract

Using RR Lyrae stars in the Gaia Data Release 2 and Pan-STARRS1 we study the properties of the Pisces Overdensity, a diffuse sub-structure in the outer halo of the Milky Way. We show that along the line of sight, Pisces appears as a broad and long plume of stars stretching from 40 to 110 kpc with a steep distance gradient. On the sky Pisces's elongated shape is aligned with the Magellanic Stream. Using follow-up VLT FORS2 spectroscopy, we have measured the velocity distribution of the Pisces candidate member stars and have shown it to be as broad as that of the Galactic halo but offset to negative velocities. Using a suite of numerical simulations, we demonstrate that the structure has many properties in common with the predicted behaviour of the Magellanic wake, i.e. the Galactic halo overdensity induced by the in-fall of the Magellanic Clouds.

Submitted to MNRAS Letters. Comments welcome!

References in corpus (6)

• Ultralight scalars as cosmological dark matter
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• The Origin of the Magellanic Stream and Its Leading Arm
• Action-based distribution functions for spheroidal galaxy components
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Cited by in corpus (6)

• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• Quantifying the Stellar Halo's Response to the LMC's Infall with Spherical Harmonics
• Comparing hypervelocity star populations from the Large Magellanic Cloud and the Milky Way
• Discovery of NES, an extended tidal structure in the North-East of the Large Magellanic Cloud
• Effect of the Solar dark matter wake on planets
• Tracing Milky Way substructure with an RR Lyrae hierarchical clustering forest