The Stellar Density Profile of the Distant Galactic Halo

Abstract

We use extensive gravity-sensitive DDO 51 photometry over 5100 square degrees, combined with SDSS broadband photometry, to select a catalog of $\sim 4,000$ giant stars covering a large fraction of the high Galactic latitude sky and reaching out to $\sim 80$ kpc in the Galactic halo. This sample of bright and unbiased tracers enables us to measure the radial profile and 3D structure of the stellar halo to large distance which had previously only been measured with sparse tracers or small samples. Using population synthesis models to reproduce the observed giant star luminosity function, we find that the halo maintains a $r^{-3.5}$ profile from $30$ to $80$ kpc with no signs of a truncation or sharp break over this range. The radial profile measurement is largely insensitive to individual halo substructure components, but we find that attempting to measure the shape of the halo is overwhelmed by the Sagittarius stream such that no ellipsoidal shape is a satisfactory description in this region. These measurements allow us to begin placing the Milky Way in context with the growing sample of external galaxies where similar halo profile measurements are available, with the goal of further linking the properties of stellar halos to the accretion histories that formed them.

Accepted to ApJ

References in corpus (7)

• The Dartmouth Stellar Evolution Database
• The Milky Way Tomography with SDSS: II. Stellar Metallicity
• The accretion origin of the Milky Way's stellar halo
• The Dual Origin of Stellar Halos
• Touching The Void: A Striking Drop in Stellar Halo Density Beyond 50 kpc
• The Complex Structure of Stars in the Outer Galactic Disk as revealed by Pan-STARRS1
• A skewer survey of the Galactic halo from deep CFHT and INT images

Cited by in corpus (7)

• The total stellar halo mass of the Milky Way
• The Outer Halo of the Milky Way as Probed by RR Lyr Variables from the Palomar Transient Facility
• The stellar halo of the Milky Way traced by blue horizontal-branch stars in the Subaru Hyper Suprime-Cam Survey
• To the Galactic Virial Radius with Hyper Suprime-Cam
• Morphological Star-Galaxy Separation
• Tomography of stellar halos: what does anisotropy in a stellar halo tell us?
• Probing the spatial and velocity anisotropies in stellar halos from the Aquarius simulations