Discs of Satellites: the new dwarf spheroidals

TL;DR

This paper compares the spatial distributions of ultra faint dwarf satellites around the Milky Way and Andromeda to the known discs-of-satellites, highlighting their statistical significance and phase-space correlation.

Contribution

It demonstrates that new Milky Way satellites align with the discs-of-satellites, reinforcing their physical reality despite observational biases.

Findings

New Milky Way satellites follow the disc-of-satellites pattern

Similar results found for Andromeda satellites

Deficit of satellites beyond 100 kpc from the Galactic center

Abstract

The spatial distributions of the most recently discovered ultra faint dwarf satellites around the Milky Way and the Andromeda galaxy are compared to the previously reported discs-of-satellites (DoS) of their host galaxies. In our investigation we pay special attention to the selection bias introduced due to the limited sky coverage of SDSS. We find that the new Milky Way satellite galaxies follow closely the DoS defined by the more luminous dwarfs, thereby further emphasizing the statistical significance of this feature in the Galactic halo. We also notice a deficit of satellite galaxies with Galactocentric distances larger than 100 kpc that are away from the disc-of-satellites of the Milky Way. In the case of Andromeda, we obtain similar results, naturally complementing our previous finding and strengthening the notion that the discs-of-satellites are optical manifestations of a phase-space correlation of satellite galaxies.