The Shape and Profile of the Milky Way Halo as Seen by the CFHT Legacy Survey

Abstract

We use Canada-France-Hawaii Telescope Legacy Survey data for 170 deg^2, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of ~35 kpc. We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R_{gal}~28 kpc, with the power law index changing from n_{inner}=-2.62+-0.04 to n_{outer}=-3.8+-0.1. In particular, we test a series of single power law models and find them to be strongly disfavored by the data. The parameters for the best-fit Einasto profile are n=2.2+-0.2 and R_e=22.2+-0.4 kpc. We measure the oblateness of the halo to be q=c/a=0.70+-0.01 and detect no evidence of it changing across the range of probed distances. The Sagittarius stream is detected in the l=173 and b=-62 direction as an overdensity of [Fe/H] ~ -1.5 dex stars at R_{gal}~32 kpc, providing a new constraint for the Sagittarius stream and dark matter halo models. We also detect the Monoceros stream as an overdensity of [Fe/H] > -1.5 dex stars in the l=232 and b=26 direction at R_{gal}<25 kpc. In the two sightlines where we do not detect significant substructure, the median metallicity is found to be independent of distance within systematic uncertainties ([Fe/H] ~ -1.5+-0.1 dex).

Added best-fit parameters for the Einasto profile, corrected typos and references, accepted to ApJ

References in corpus (10)

• Two Stellar Components in the Halo of the Milky Way
• The Milky Way Tomography with SDSS: II. Stellar Metallicity
• The Dual Origin of Stellar Halos
• The Galaxy and its stellar halo: insights on their formation from a hybrid cosmological approach
• MegaPipe: the MegaCam image stacking pipeline at the Canadian Astronomical Data Centre
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: Variation of the Metallicity Distribution Function Along the Sagittarius Stream
• Revealing Substructure in the Galactic Halo - The SEKBO RR Lyrae Survey
• The AAT/WFI survey of the Monoceros Ring and Canis Major Dwarf galaxy: I. from l = (193 - 276)o
• Candidate Disk Wide Binaries in the Sloan Digital Sky Survey
• An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data

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