TY - JOUR
T1 - The SAMI galaxy survey
T2 - Stellar population radial gradients in early-type galaxies
AU - Ferreras, Ignacio
AU - Scott, Nicholas
AU - la Barbera, Francesco
AU - Croom, Scott
AU - van de Sande, Jesse
AU - Hopkins, Andrew
AU - Colless, Matthew
AU - Barone, Tania M.
AU - d'Eugenio, Francesco
AU - Bland-Hawthorn, Joss
AU - Brough, Sarah
AU - Bryant, Julia J.
AU - Konstantopoulos, Iraklis S.
AU - Lagos, Claudia
AU - Lawrence, Jon S.
AU - López-Sánchez, Angel
AU - Medling, Anne M.
AU - Owers, Matt S.
AU - Richards, Samuel N.
N1 - Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2019/10/11
Y1 - 2019/10/11
N2 - 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 (∇) and central value of the fits (evaluated at Re/4) are compared against a set of six observables that may act as drivers of the trends. We find that velocity dispersion (σ) - 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 ∇[Mg/Fe] with increasing σ is contrasted by a rather shallow dependence of ∇[Z/H] with σ (although this radial gradient is overall rather steep). This result, along with a shallow age slope at the massive end, imposes a substantial constraint on the progenitors of the populations that contribute to the formation of the outer envelopes of ETGs. The SAMI sample is split, by design, between 'field' and cluster galaxies. Only weak environment-related differences are found, most notably a stronger dependence of central total metallicity ([Z/H]e4) with σ, along with a marginal trend of ∇[Z/H] to steepen in cluster galaxies, a result that is not followed by [Mg/Fe]. The results presented here serve as stringent constraints on numerical models of the formation and evolution of ETGs.
AB - 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 (∇) and central value of the fits (evaluated at Re/4) are compared against a set of six observables that may act as drivers of the trends. We find that velocity dispersion (σ) - 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 ∇[Mg/Fe] with increasing σ is contrasted by a rather shallow dependence of ∇[Z/H] with σ (although this radial gradient is overall rather steep). This result, along with a shallow age slope at the massive end, imposes a substantial constraint on the progenitors of the populations that contribute to the formation of the outer envelopes of ETGs. The SAMI sample is split, by design, between 'field' and cluster galaxies. Only weak environment-related differences are found, most notably a stronger dependence of central total metallicity ([Z/H]e4) with σ, along with a marginal trend of ∇[Z/H] to steepen in cluster galaxies, a result that is not followed by [Mg/Fe]. The results presented here serve as stringent constraints on numerical models of the formation and evolution of ETGs.
KW - CD
KW - Galaxies: elliptical and lenticular
KW - Galaxies: evolution
KW - Galaxies: formation
KW - Galaxies: stellar content
UR - http://www.scopus.com/inward/record.url?scp=85075234754&partnerID=8YFLogxK
U2 - 10.1093/mnras/stz2095
DO - 10.1093/mnras/stz2095
M3 - Review article
SN - 0035-8711
VL - 489
SP - 608
EP - 622
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -