The SAMI Galaxy Survey: Stellar population radial gradients in early-type galaxies

Abstract

We study the internal radial gradients of the stellar populations in a sample comprising 522 early-type galaxies (ETGs) from the SAMI (Sydney- AAO Multi-object Integral field spectrograph) Galaxy Survey. We stack the spectra of individual spaxels in radial bins, and derive basic stellar population properties: total metallicity ([Z/H]), [Mg/Fe], [C/Fe] and age. The radial gradient ($\nabla$) and central value of the fits (evaluated at R${}_e$/4) are compared against a set of six possible drivers of the trends. We find that velocity dispersion ($\sigma$) - or, equivalently gravitational potential - is the dominant driver of the chemical composition gradients. Surface mass density is also correlated with the trends, especially with stellar age. The decrease of $\nabla$[Mg/Fe] with increasing $\sigma$ is contrasted by a rather shallow dependence of $\nabla$[Z/H] with $\sigma$ (although this radial gradient is overall rather steep). This result, along with a shallow age slope at the massive end, imposes stringent constraints on the progenitors of the populations that contribute to the formation of the outer envelopes of ETGs. The SAMI sample is split between a 'field' sample and a cluster sample. Only weak environment-related differences are found, most notably a stronger dependence of central total metallicity ([Z/H]${}_{e4}$) with $\sigma$, along with a marginal trend of $\nabla$[Z/H] to steepen in cluster galaxies, a result that is not followed by [Mg/Fe]. The results presented here serve as constraints on numerical models of the formation and evolution of ETGs.

arXiv comment14 pages, 9 figures, 3 tables. Submitted to MNRAS

References in corpus (70)

• emcee: The MCMC Hammer
• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• The epochs of early-type galaxy formation as a function of environment
• MILES: A Medium resolution INT Library of Empirical Spectra
• CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation
• The Atlas3D project -- I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria
• The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the fundamental plane of elliptical and lenticular galaxies
• Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release
• Passively Evolving Early-type Galaxies at 1.4<z<2.5 in the Hubble Ultra Deep Field
• The Two Phases of Galaxy Formation
• Confirmation of the remarkable compactness of massive quiescent galaxies at z~2.3: early-type galaxies did not form in a simple monolithic collapse
• Properties of Galaxy Groups in the SDSS: I.-- The Dependence of Colour, Star Formation, and Morphology on Halo Mass
• The Stellar Population Histories of Early-Type Galaxies. II. Controlling Parameters of the Stellar Populations
• Old Stellar Populations. VI. Absorption-Line Spectra of Galaxy Nuclei and Globular Clusters
• The SAURON project. I. The panoramic integral-field spectrograph
• The Sydney-AAO Multi-object Integral field spectrograph (SAMI)
• The size evolution of galaxies since z~3: combining SDSS, GEMS and FIRES
• The SAMI Galaxy Survey: instrument specification and target selection
• Stellar Population Diagnostics of Elliptical Galaxy Formation
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• Population Synthesis in the Blue IV: Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
• Galaxy And Mass Assembly (GAMA): Structural Investigation of Galaxies via Model Analysis (SIGMA)
• Environment and self-regulation in galaxy formation
• The CALIFA survey across the Hubble sequence: Spatially resolved stellar population properties in galaxies
• SPIDER VIII - Constraints on the Stellar Initial Mass Function of Early-type Galaxies from a Variety of Spectral Features
• Counting Low-Mass Stars in Integrated Light
• Systematic variation of the stellar Initial Mass Function with velocity dispersion in early-type galaxies
• Stellar Population gradients in galaxy discs from the CALIFA survey
• Early-type galaxies in the SDSS. IV. Colors and chemical evolution
• Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios
• Radial variations in the stellar initial mass function of early-type galaxies
• The Stellar Initial Mass Function in Early-Type Galaxies from Absorption Line Spectroscopy. III. Radial Gradients
• The SAMI Galaxy Survey: the link between angular momentum and optical morphology
• The SAMI Galaxy Survey: Revisiting Galaxy Classification Through High-Order Stellar Kinematics
• Building galaxies by accretion and in-situ star formation
• Focal ratio degradation in lightly-fused hexabundles
• Ages and Abundances of Red Sequence Galaxies as a Function of LINER Emission Line Strength
• Chemical element ratios of SDSS early-type galaxies
• The stellar accretion origin of stellar population gradients in massive galaxies at large radii
• SPIDER VII - Revealing the Stellar Population Content of Massive Early-type Galaxies out to 8Re
• The SAMI Galaxy Survey: Global stellar populations on the size-mass plane
• Radial constraints on the Initial Mass Function from TiO features and Wing-Ford band in Early-type Galaxies
• Environmental quenching and hierarchical cluster assembly: Evidence from spectroscopic ages of red-sequence galaxies in Coma
• The SAMI Galaxy Survey: Data Release Two with absorption-line physics value-added products
• The SAMI Galaxy Survey: The cluster redshift survey, target selection and cluster properties
• Timing the formation and assembly of early-type galaxies via spatially resolved stellar populations analysis
• SDSS-IV MaNGA: stellar population gradients as a function of galaxy environment
• The link between the Star Formation History and [alpha/Fe]
• An optimized H_βindex for disentangling stellar population ages
• The SAMI Galaxy Survey: Quenching of star formation in clusters I. Transition galaxies
• A relation between characteristic stellar age of galaxies and their intrinsic shape
• The information content of stellar halos: Stellar population gradients and accretion histories in early-type Illustris galaxies
• Line Strengths in Early-Type Cluster Galaxies at z=0.33: Implications for alpha/Fe, Nitrogen and the Histories of E/S0s
• The SAMI Galaxy Survey: gravitational potential and surface density drive stellar populations -- I. early-type galaxies
• SPIDER X - Environmental effects in central and satellite early-type galaxies through the stellar fossil record
• SDSS-IV MaNGA: local and global chemical abundance patterns in early-type galaxies
• Integral-field kinematics and stellar populations of early-type galaxies out to three half-light radii
• Abundance ratios in red-sequence galaxies over a wide mass range: The "X-planes" for magnesium, calcium, carbon and nitrogen
• The gas-phase metallicities of star-forming galaxies in aperture-matched SDSS samples follow potential rather than mass or average surface density
• Resolving the baryon-fraction profile in lensing galaxies
• On the Radial Stellar Content of Early-Type Galaxies as a Function of Mass and Environment
• The Role of Environment on the Formation of Early-Type Galaxies
• The Influence of Galaxy Environment on the Stellar Initial Mass Function of Early-Type Galaxies
• The stellar populations of early-type galaxies -- II. The effects of environment and mass

Cited by in corpus (35)

• The SAMI Galaxy Survey: the third and final data release
• SDSS-IV MaNGA: Radial Gradients in Stellar Population Properties of Early-Type and Late-Type Galaxies
• Galaxy properties as revealed by MaNGA. I. Constraints on Initial Mass Function and M${}_{\ast }$/L gradients in ellipticals
• The SAMI Galaxy Survey: stellar population gradients of central galaxies
• Galaxy properties as revealed by MaNGA II. Differences in stellar populations of slow and fast rotator ellipticals and dependence on environment
• Abell 1201: Detection of an Ultramassive Black Hole in a Strong Gravitational Lens
• Inverse stellar population age gradients of post-starburst galaxies at z=0.8 with LEGA-C
• Galaxy properties as revealed by MaNGA. III. Kinematic profiles and stellar population gradients in S0s
• Gravitational Potential and Surface Density Drive Stellar Populations -- II. Star-Forming Galaxies
• A preserved high-z compact progenitor in the heart of NGC3311 revealed with MUSE 2D stellar population analysis
• A detailed look at the stellar populations in green valley galaxies
• An exquisitely deep view of quenching galaxies through the gravitational lens: Stellar population, morphology, and ionized gas
• Fingerprints of Stellar Populations in the Near-Infrared: An Optimised Set of Spectral Indices in the JHK-Bands
• Mapping Accreted Stars in Early-Type Galaxies Across the Mass-Size Plane
• The Fornax3D project: Environmental effects on the assembly of dynamically cold disks in Fornax cluster galaxies
• Young stellar population gradients in central cluster galaxies from NUV and optical spectroscopy
• Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey
• A Precise Benchmark for Cluster Scaling Relations: Fundamental Plane, Mass Plane and IMF in the Coma Cluster from Dynamical Models
• The Fornax3D project: The assembly history of massive early-type galaxies in the Fornax cluster from deep imaging and integral field spectroscopy
• The evolution of radial gradients of MaNGA quiescent elliptical galaxies: inside-out quenching or outer mass growth?
• Stellar Population and Elemental Abundance Gradients of Early-type Galaxies
• Evaluating hydrodynamical simulations with green valley galaxies
• On the assembly history of massive galaxies. A pilot project with VEGAS deep imaging and M3G integral field spectroscopy
• Impact of Galaxy Mergers on Stellar Population Profiles of Early-type Galaxies
• Ages and metallicities of quiescent galaxies: confronting broadband ($UVJ$) colours with stellar absorption lines
• Age and metal gradients in massive quiescent galaxies at $0.6\lesssim z\lesssim 1.0$: implications for quenching and assembly histories
• The properties and environment of very young galaxies in the local Universe
• Stellar population gradients at cosmic noon as a constraint to the evolution of passive galaxies
• Exploring the stellar populations of backsplash galaxies
• Testing the role of AGN on the star formation and metal enrichment of "twin galaxies"
• A novel approach for calculating galaxy rotation curves using spaxel cross-correlation and iterative smoothing
• A MaNGA about the Legacy I: Connecting the Assembly of Stellar Halo with the Average Star Formation History in Low-Redshift Massive Galaxies
• Cosmography via stellar archaeology of low-redshift early-type galaxies from SDSS
• Fornax 3D project: assessing the diversity of IMF and stellar population maps within the Fornax Cluster
• Evaluating quenching in cosmological simulations of galaxy formation with spectral covariance in the optical window