The outermost stellar halo of NGC 5128 (Centaurus A): Radial structure

Abstract

The extended stellar halos of galaxies contain important clues for investigating their assembly history and evolution. We investigate the resolved stellar content and the extended halo of NGC 5128 as a function of galactocentric distance. We used HST images to resolve individual red giant branch (RGB) stars in 28 independent pointings. Star counts from deep VI color-magnitude diagrams reaching at least 1.5 mag below the tip of the RGB are used to derive the surface density distribution of the halo. The contamination by Milky Way stars is assessed with a new control field, with models, and by combining optical and near-IR photometry. We present a new calibration of the WFC3 F606W+F814W photometry to the ground-based VI photometric system. The photometry shows that the stellar halo of NGC 5128 is dominated by old RGB stars that are present in all fields. The V-band surface brightness changes from 23 to 32 mag/arcsec${}^2$ between 8.3 kpc from the galaxy center to our outermost halo fields located 140 kpc away from the center along the major axis and 92 kpc along the minor axis. Within ~30 kpc, we also find evidence for a 2-3 Gyr old population traced by bright asymptotic giant branch stars. This population contributes only up to 10% in total stellar mass if it is 2 Gyr old, but a larger fraction of 30-40% is required if its age is 3 Gyr. The stellar surface density profile is well fit by a r${}^{1/4}$ curve or a power-law $\sim r^{-3.1}$ over the full radial range, with no obvious break in the slope, but with large field-to-field scatter. The ellipticity measured from integrated-light photometry in the inner parts, $e=(b/a)=0.77$, flattens to $e=0.54\pm 0.02$ beyond 30 kpc. Considering the flattening of the outer halo, the projection of the elliptical isophote on the semimajor axis for our most distant field reaches nearly 30 effective radii. [abridged]

arXiv comment23 pages, 24 figures, accepted for publication in A&A

References in corpus (78)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Photometric Performance and Calibration of the HST Advanced Camera For Surveys
• Minor mergers and the size evolution of elliptical galaxies
• The Field of Streams: Sagittarius and its Siblings
• Resolving Cosmic Structure Formation with the Millennium-II Simulation
• The Two Phases of Galaxy Formation
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Two Stellar Components in the Halo of the Milky Way
• Galactic stellar haloes in the CDM model
• The accretion origin of the Milky Way's stellar halo
• Calibration of the Tip of the Red Giant Branch (TRGB)
• Evidence for Stellar Substructure in the Halo and Outer Disk of M31
• The Atlas3D project -- XXIX. The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
• Tip of the Red Giant Branch Distances. II. Zero-Point Calibration
• Evolution of Thermally Pulsing Asymptotic Giant Branch Stars I. The COLIBRI Code
• The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties
• The Frequency of Tidal Features Associated with Nearby Luminous Elliptical Galaxies from a Statistically Complete Sample
• Probing the Outer Galactic halo with RR Lyrae from the Catalina Surveys
• The Distance to NGC 5128 (Centaurus A)
• The extended halo of Centaurus A: uncovering satellites, streams, and substructures
• Constraining the thermally-pulsing asymptotic giant branch phase with resolved stellar populations in the Small Magellanic Cloud
• The Hubble flow around the CenA / M83 galaxy complex
• Galactic accretion and the outer structure of galaxies in the CDM model
• The Halo Stars in NGC 5128. III: An Inner-Halo Field and the Metallicity Distribution
• A new IR-Array photometric survey of Galactic Globular Clusters: A detailed study of the RGB sequence as a step towards the global testing of stellar models
• The Fornax Deep Survey with VST. I. The extended and diffuse stellar halo of NGC~1399 out to 192 kpc
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• The Shape and Profile of the Milky Way Halo as Seen by the CFHT Legacy Survey
• The Metallicity Distribution in the Halo Stars of NGC 5128: Implications for Galaxy Formation
• The distance to the giant elliptical galaxy NGC 5128
• The Dragonfly Nearby Galaxies Survey. I. Substantial variation in the diffuse stellar halos around spiral galaxies
• Deep ACS Imaging of the Halo of NGC 5128: Reaching the Horizontal Branch
• Diverse Stellar Haloes in Nearby Milky Way-Mass Disc Galaxies
• The Inner Halo of M87: A First Direct View of the Red-Giant Population
• Individual Stellar Halos of Massive Galaxies Measured to 100 kpc at $0.3<z<0.5$ using Hyper Suprime-Cam
• The GHOSTS survey. II. The diversity of Halo Color and Metallicity Profiles of Massive Disk Galaxies
• Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile
• The faint end of the Centaurus A satellite luminosity function
• The Metallicity Distribution of Intracluster Stars in Virgo
• The Ages, Metallicities and Alpha Element Enhancements of Globular Clusters in the Elliptical NGC 5128: A Homogeneous Spectroscopic Study with Gemini/GMOS
• A Young Blue Tidal Stream in NGC 5128
• Angular Momentum and Galaxy Formation Revisited: Scaling Relations for Disks and Bulges
• The dwarf galaxy satellite system of Centaurus A
• Census and classification of low-surface-brightness structures in nearby early-type galaxies from the MATLAS survey
• The faint stellar halos of massive red galaxies from stacks of more than 42000 SDSS LRG images
• The Leo Elliptical NGC 3379: A Metal-Poor Halo Emerges
• Centaurus A: morphology and kinematics of the atomic hydrogen
• The Fornax Deep Survey with VST. V. Exploring the faintest regions of the bright early-type galaxies inside the virial radius
• How old are the stars in the halo of NGC 5128 (Centaurus A)?
• New low surface brightness dwarf galaxies in the Centaurus group
• Triggered star-formation in the inner filament of Centaurus A
• Anomalous HI kinematics in Centaurus A: evidence for jet-induced star formation
• The Satellite Luminosity Functions of Galaxies in SDSS
• Stellar populations in NGC 5128 with the VLT: evidence for recent star formation
• The stellar halos of ETGs in the IllustrisTNG simulations: II. Accretion, merger history, and dark halo connection
• The radio/optical alignment and the recent star formation associated with ionized filaments in the halo of NGC 5128 (Centaurus A)
• Globular Cluster Systems in Brightest Cluster Galaxies. II: NGC 6166
• Tracing the outer halo in a giant elliptical to 25 Reff
• HST Photometry for the Halo Stars in the Leo Elliptical NGC 3377
• Stellar Populations in the Outer Halo of the Massive Elliptical M49
• Detection of a distinct metal-poor stellar halo in the early-type galaxy NGC 3115
• Star formation efficiency along the radio jet in Centaurus A
• The Outer Halo of the Nearest Giant Elliptical: A VLT/VIMOS Survey of the Resolved Stellar Populations in Centaurus A to 85 kpc
• A Recent Major Merger Tale for the Closest Giant Elliptical Galaxy Centaurus A
• NGC 5128: The Giant Beneath
• The Survey of Centaurus A's Baryonic Structures (SCABS). II. The Extended Globular Cluster System of NGC5128 and its Nearby Environment
• Long Period Variables in NGC 5128: II. Near-IR properties
• NGC 5128 globular cluster candidates out to 150 kpc: a comprehensive catalog from Gaia and ground based data
• The jet-ISM interaction in the Outer Filament of Centaurus A
• Long Period Variables in NGC 5128: I. Catalogue
• The Strikingly Metal-Rich Halo of the Sombrero Galaxy
• Simulating the recent star formation history in the halo of NGC 5128
• Stellar halos and elliptical galaxy formation: Origin of dynamical properties of the planetary nebular systems
• Studying the metallicity gradient in Virgo Ellipticals with E-ELT photometry of resolved stars
• Red giants in the outer halo of the elliptical galaxy NGC 5128 / Centaurus A
• Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey

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