Blanco DECam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results

Abstract

The Blanco DECam Bulge Survey (BDBS) imaged more than 200 square degrees of the Southern Galactic bulge using the ugrizY filters of the Dark Energy Camera, and produced point spread function photometry of approximately 250 million unique sources. In this paper, we present details regarding the construction and collation of survey catalogs, and also discuss the adopted calibration and dereddening procedures. Early science results are presented with a particular emphasis on the bulge metallicity distribution function and globular clusters. A key result is the strong correlation (sigma ~ 0.2 dex) between (u-i)o and [Fe/H] for bulge red clump giants. We utilized this relation to find that interior bulge fields may be well described by simple closed box enrichment models, but fields exterior to b ~ -6 degrees seem to require a secondary metal-poor component. Applying scaled versions of the closed box model to the outer bulge fields is shown to significantly reduce the strengths of any additional metal-poor components when compared to Gaussian mixture models. Additional results include: a confirmation that the u-band splits the sub-giant branch in M 22 as a function of metallicity, the detection of possible extra-tidal stars along the orbits of M 22 and FSR 1758, and additional evidence that NGC 6569 may have a small but discrete He spread, as evidenced by red clump luminosity variations in the reddest bands. We do not confirm previous claims that FSR 1758 is part of a larger extended structure.

Accepted for publication in MNRAS; 26 pages

References in corpus (41)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The Dartmouth Stellar Evolution Database
• The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
• The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+)
• A systematic survey for infrared star clusters with |b|<20deg using 2MASS
• Chemical similarities between Galactic bulge and local thick disk red giant stars
• Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
• The GIRAFFE Inner Bulge Survey (GIBS) III. Metallicity distributions and kinematics of 26 Galactic bulge fields
• The VISTA ZYJHKs Photometric System: Calibration from 2MASS
• ARGOS II: The Galactic Bulge Survey
• Light, Alpha, and Fe-Peak Element Abundances in the Galactic Bulge
• The Bulge Radial Velocity Assay (BRAVA): I. Techniques and a Rotation Curve
• Kinematics at the Edge of the Galactic Bulge: Evidence for Cylindrical Rotation
• A Sequoia in the Garden: FSR 1758 - Dwarf Galaxy or Giant Globular Cluster?
• The age of the young bulge-like population in the stellar system Terzan5: linking the Galactic bulge to the high-z Universe
• High-resolution abundance analysis of red giants in the globular cluster NGC 6522
• A parametric description of the 3D structure of the Galactic Bar/Bulge using the VVV survey
• The age of the Milky Way inner stellar spheroid from RR Lyrae population synthesis
• The Chemical Composition of the Galactic Bulge and Implications for its Evolution
• Evidence of a Metal Rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
• The inner two degrees of the Milky Way. Evidence of a chemical difference between the Galactic Center and the surrounding inner bulge stellar populations
• The Bulge Metallicity Distribution from the APOGEE Survey
• Spectroscopic Signatures of Extra-Tidal Stars Around the Globular Clusters NGC 6656 (M22), NGC 3201 and NGC 1851 from RAVE
• A Chemical Composition Survey of the Iron-Complex Globular Cluster NGC 6273 (M 19)
• Mapping the stellar age of the Milky Way bulge with the VVV. I. The method
• A spectroscopic study of the Globular Cluster M28 (NGC~6626)
• Abundances of disk and bulge giants from hi-res optical spectra: II. O, Mg, Ca, and Ti in the bulge sample
• Mapping the Interstellar Reddening and Extinction towards Baade's Window Using Minimum Light Colors of ab-type RR Lyrae Stars. Revelations from the De-reddened Color-Magnitude Diagrams
• Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569
• NGC 6522: A typical globular cluster in the Galactic bulge without signatures of rapidly rotating Population III stars
• On the metallicity distribution of the peculiar globular cluster M22
• Was the Milky Way Bulge Formed From The Buckling Disk Instability, Hierarchical Collapse, Accretion of Clumps, or All of the Above?
• On the Correlation Between Metallicity and the X-Shaped Morphology of the Milky Way Bulge
• Common Origin of Two RR Lyrae Populations and the Double Red Clump in the Milky Way Bulge
• Formation of N-rich field stars in the high-density building blocks of the Galactic bulge
• HERBS I: Metallicity and alpha enhancement along the Galactic bulge minor axis
• The Globular Cluster Origin of the Milky Way Outer Bulge: Evidence from Sodium Bimodality
• On the Oosterhoff dichotomy in the Galactic bulge: II. kinematical distribution
• The retrograde orbit of the globular cluster FSR1758 revealed with Gaia DR2
• Distribution of red clump stars does not support the X-shaped Galactic bulge
• Are the double-mode bulge RR Lyrae stars with identical period-ratios the relic of a disrupted stellar system?

Cited by in corpus (9)

• Blanco DECam Bulge Survey (BDBS) III: A new view of the double red clump in the Milky Way bulge through luminosity and color distribution
• Difference in chemical composition between the bright and faint red clump stars in the Milky Way bulge
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Mapping the tilt of the Milky Way bulge velocity ellipsoids with ARGOS and $Gaia$ DR2
• From Galactic Chemical Evolution to Cosmic Supernova Rates Synchronized with Core-Collapse Supernovae Limited to the Narrow Progenitor Mass Range
• He-star donor AM CVn stars and their progenitors as LISA sources
• A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions
• Blanco DECam Bulge Survey (BDBS) IV: Metallicity Distributions and Bulge Structure from 2.6 Million Red Clump Stars
• The COMBS Survey -- III. The Chemodynamical Origins of Metal-Poor Bulge Stars