Detection of a population gradient in the Sagittarius Stream

Abstract

We present a quantitative comparison between the Horizontal Branch morphology in the core of the Sagittarius dwarf spheroidal galaxy (Sgr) and in a wide field sampling a portion of its tidal stream (Sgr Stream), located tens of kpc away from the center of the parent galaxy. We find that the Blue Horizontal Branch (BHB) stars in that part of the Stream are five times more abundant than in the Sgr core, relative to Red Clump stars. The difference in the ratio of BHB to RC stars between the two fields is significant at the 4.8 sigma level. This indicates that the old and metal-poor population of Sgr was preferentially stripped from the galaxy in past peri-Galactic passages with respect to the intermediate-age metal rich population that presently dominates the bound core of Sgr, probably due to a strong radial gradient that was settled within the galaxy before its disruption. The technique adopted in the present study allows to trace population gradients along the whole extension of the Stream.

4 pages, 3 .ps figures (fig. 1 at low resolution); Accepted for publication by A&A Letters

References in corpus (14)

• The u'g'r'i'z' Standard Star Network
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The Field of Streams: Sagittarius and its Siblings
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails
• Population Gradients in Local Group Dwarf Spheroidals
• Building up the globular cluster system of the Milky Way. The contribution of the Sagittarius galaxy
• The Ital-FLAMES survey of the Sagittarius dwarf Spheroidal galaxy. I. Chemical abundances of bright RGB stars
• Tracing out the Northern Tidal Stream of the Sagittarius Dwarf Spheoridal Galaxy
• The distance to the Sgr dwarf spheroidal galaxy from the Red Giant Branch Tip
• The age of the main population of the Sagittarius dwarf spheroidal galaxy. Solving the "M giant conundrum"
• RR Lyrae stars in the Sagittarius dwarf galaxy: Period analysis
• Blue Horizontal Branch Stars in the Sagittarius dwarf spheroidal galaxy

Cited by in corpus (42)

• The Sagittarius Dwarf Galaxy: a Model for Evolution in a Triaxial Milky Way Halo
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation
• The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy
• Precession of the Sagittarius stream
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• The Sagittarius Streams in the Southern Galactic Hemisphere
• The ghost of a dwarf galaxy: fossils of the hierarchical formation of the nearby spiral galaxy NGC 5907
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: Variation of the Metallicity Distribution Function Along the Sagittarius Stream
• Tracing Sagittarius Structure with SDSS and SEGUE Imaging and Spectroscopy
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• A spectroscopic confirmation of the Bootes II dwarf spheroidal
• Mapping the Galactic Halo VIII: Quantifying substructure
• Stellar Streams and Clouds in the Galactic Halo
• The satellites of the Milky Way - Insights from semi-analytic modelling in a LambdaCDM cosmology
• High-resolution spectroscopy of RGB stars in the Sagittarius Streams. I. Radial velocities and chemical abundances
• The Stellar Content of Galaxy Halos: A Comparison between LambdaCDM Models and Observations of M31
• Metallicity and $\alpha$-element Abundance Gradients along the Sagittarius Stream as Seen by APOGEE
• Chemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxy
• A massive mess: When a large dwarf and a Milky Way-like galaxy merge
• Chemical Inhomogeneities in the Milky Way Stellar Halo
• Stellar Population Variations in the Milky Way's Stellar Halo
• Kinematics and Chemistry of Stars Along the Sagittarius Trailing Tidal Tail and Constraints on the Milky Way Mass Distribution
• Chemical abundances of hydrostatic and explosive alpha-elements in Sagittarius stream stars
• A Pan-STARRS1 View of the Bifurcated Sagittarius Stream
• Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables
• The Northern wraps of the Sagittarius Stream as traced by Red Clump stars: distances, intrinsic widths and stellar densities
• Phase-space Properties and Chemistry of the Sagittarius Stellar Stream Down to the Extremely Metal-poor ($[Fe/H]\lesssim -3$) Regime
• A wide angle view of the Sagittarius dwarf Spheroidal Galaxy. I: VIMOS photometry and radial velocities across Sgr dSph major and minor axis
• Exploring the Sagittarius Stream with SEKBO Survey RR Lyrae Stars
• A spectroscopic survey of faint, high-Galactic-latitude red clump stars. I. The high resolution sample
• VISTA's view of the Sagittarius dwarf spheroidal galaxy and southern Galactic Bulge
• STREGA: STRucture and Evolution of the GAlaxy. I. Survey Overview and First Results
• Red Clump stars in the Bootes III stellar system
• The metallicity distribution in the core of the Sagittarus dwarf spheroidal: minimising the metallicity biases
• The STREGA survey. II. Globular Cluster Palomar 12
• Stellar Tidal Streams in External Galaxies
• Identifying Star Streams in the Milky Way Halo
• A chemical close-up of the main body of the Sagittarius dwarf galaxy
• Exploring the Sagittarius stream with RR Lyrae Stars from Gaia Data Release 3
• Chemo-dynamical reconstruction of Milky Way globular cluster progenitors: Age-metallicity relations and the universality of multiple stellar populations
• The Future of Stellar Populations Studies in the Milky Way and the Local Group