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.

arXiv comment16 pages, 24 figures, accepted by MNRAS

References in corpus (28)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The Field of Streams: Sagittarius and its Siblings
• Two Stellar Components in the Halo of the Milky Way
• LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
• The accretion origin of the Milky Way's stellar halo
• The Milky Way stellar halo out to 40 kpc : Squashed, broken but smooth
• Stars beyond Galaxies: The Origin of Extended Luminous Halos around Galaxies
• Substructure revealed by RR Lyraes in SDSS Stripe 82
• Rings and Radial Waves in the Disk of the Milky Way
• Starcounts Redivivus. IV. Density Laws Through Photometric Parallaxes
• Light Curve Templates and Galactic Distribution of RR Lyrae Stars from Sloan Digital Sky Survey Stripe 82
• Precession of the Sagittarius stream
• Broken and unbroken: the Milky Way and M31 stellar haloes
• The QUEST RR Lyrae Survey II: The Halo Overdensities in the First Catalog
• The Spheroid Luminosity and Mass Functions From HST Star Counts
• The radial profile and flattening of the Milky Way's stellar halo to $80$kpc from the SEGUE K-giant Survey
• The SEGUE K giant survey II: A Catalog of Distance Determinations for the SEGUE K giants in the Galactic Halo
• 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
• Mapping the Milky Way with LAMOST I: Method and overview
• 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
• Red Clump Stars from the LAMOST data I: identification and distance
• Red Clump stars from LAMOST II: the outer disc of the Milky Way

Cited by in corpus (26)

• Overview of the LAMOST survey in the first decade
• Mapping the Milky Way with LAMOST III: Complicated spatial structure in the outer disc
• Stellar Initial Mass Function Varies with Metallicities and Time
• Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
• The Galactic Thick Disc density profile traced with RR Lyrae stars
• The value-added catalogue for LAMOST DR8 low-resolution spectra
• Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
• Probing the galactic halo with RR Lyrae stars I: The catalog
• Milky Way Mass with K Giants and BHB Stars Using LAMOST, SDSS/SEGUE, and Gaia: 3D Spherical Jeans Equation and Tracer Mass Estimator
• Rotating halo traced by the K giant stars from LAMOST and Gaia
• Disk stars in the Milky Way detected beyond 25 kpc from its center
• The stellar halo of the Milky Way traced by blue horizontal-branch stars in the Subaru Hyper Suprime-Cam Survey
• Stellar halos from The Dragonfly Edge-on Galaxies Survey
• The Pristine survey -- VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars
• Identifying Galactic Halo Substructure in 6D Phase-space Using $\sim$13,000 LAMOST K Giants
• Structure of the Milky Way stellar halo out to its outer boundary with blue horizontal-branch stars
• The Flare and Warp of the Young Stellar Disk traced with LAMOST DR5 OB-type stars
• Constructing the Milky Way Stellar Halo in the Galactic Center by Direct Orbit Integration
• Differential rotation of the halo traced by the K-giant stars
• Influence of the Gaia-Sausage-Enceladus on the density shape of the Galactic stellar halo revealed by halo K giants from the LAMOST survey
• A Catalog of Distance Determinations for the LAMOST DR8 K Giants in the Galactic Halo
• The Data Processing of the LAMOST Medium-Resolution Spectral Survey of Galactic Nebulae (LAMOST MRS-N Pipeline)
• Atmospheric parameters and kinematic information for the M giants stars from LAMOST DR9
• Mapping the Milky Way's stellar halo with 2D data
• A Vertically Orientated Dark Matter Halo Marks a Flip of the Galactic Disk
• Mapping the Milky Way with Gaia Bp/Rp spectra-IV: the broken and asymmetric density profile of the stellar disk traced by a large sample of red clumps