Mapping the Milky Way with LAMOST II: the stellar halo

Abstract

The radial number density and flattening of the Milky Way's stellar halo is measured with $5351$ metal-poor ([Fe/H]$<-1$) K giants from LAMOST DR3, using a nonparametric method which is model independent and largely avoids the influence of halo substucture. The number density profile is well described by a single power law with index $5.03_{-0.64}^{+0.64}$, and flattening that varies with radius. The stellar halo traced by LAMOST K giants is more flattened at smaller radii, and becomes nearly spherical at larger radii. The flattening, $q$, is about 0.64, 0.8, 0.96 at $r=15$, 20 and 30 kpc (where $r=\sqrt{R^2+{\left[Z/q\left(r\right)\right]}^2}$), respectively. Moreover, the leading arm of the Sagittarius dwarf galaxy tidal stream in the north, and the trailing arm in the south, are significant in the residual map of density distribution. In addition, an unknown overdensity is identified in the residual map at (R,Z)=(30,15) kpc.

16 pages, 24 figures, accepted by MNRAS

References in corpus (9)

• Two Stellar Components in the Halo of the Milky Way
• The accretion origin of the Milky Way's stellar halo
• Rings and Radial Waves in the Disk of the Milky Way
• The QUEST RR Lyrae Survey II: The Halo Overdensities in the First Catalog
• The K giant stars from the LAMOST survey data I: identification, metallicity, and distance
• Touching The Void: A Striking Drop in Stellar Halo Density Beyond 50 kpc
• Characterizing stellar halo populations II: The age gradient in blue horizontal-branch stars
• A skewer survey of the Galactic halo from deep CFHT and INT images
• RR Lyrae in XSTPS: The halo density profile in the North Galactic Cap

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