CFHT UM2025 - Presentation Details
Abstract Details
Title: A Pristine-UNIONS view on the Galaxy: Kinematics of the distant spur feature of the Sagittarius stream traced by Blue Horizontal Branch stars
Presenter: Manuel Bayer
Abstract:
The halo of the Milky Way has taught us already a lot about its history. However, even in the current era of large spectroscopic surveys, only a few very bright tracers can reach the outer realms of the Milky Way halo at distances of 100 kpc and beyond to provide important constraints on the Galaxy’s past and the Galactic gravitational potential. In this talk, I will demonstrate how we can learn more about these intriguing regions by selecting blue horizontal branch stars. I will show how these standard candles can be selected in a uniquely clean and efficient way from photometry only, with the help of deep CFIS/UNIONS u-band and Pristine survey narrow-band information, to trace the most distant substructures out to 140 kpc. As a striking scientific application of this novel sample, I will present new results from very successful spectroscopic follow-up on blue horizontal branch stars in the most outer part of the Sagittarius stream – including its farthest apocentre and the even more distant 'spur'. I will discuss the implications of these data for the total mass of the Milky Way at those distances.