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Most dynamical models of galaxies to date assume axisymmetry, which is not representative of a significant fraction of massive galaxies. We have built triaxial orbit-superposition Schwarzschild models of galaxies observed by the SAMI Galaxy Survey, in order to reconstruct their inner orbital structure and mass distribution. The sample consists of 153 passive galaxies with total stellar masses in the range 109.5 to |$10^{12} \, {\rm M}_{\odot }$|⁠. We present an analysis of the internal structures and intrinsic properties of these galaxies as a function of their environment. We measure their environment using three proxies: central or satellite designation, halo mass and local 5th nearest neighbour galaxy density. We find that although these intrinsic properties correlate most strongly with stellar mass, environment does play a secondary role: at fixed stellar mass, galaxies in the densest regions are more radially anisotropic. In addition, central galaxies, and galaxies in high local densities show lower values of edge-on spin parameter proxy λRe, EO. We also find suggestions of a possible trend of the fractions of orbits with environment for lower mass galaxies (between 109.5 and |$10^{11} \, {\rm M}_{\odot }$|⁠) such that, at fixed stellar mass, galaxies in higher local densities and halo mass have higher fractions of hot orbits and lower fractions of warm orbits. Our results demonstrate that after stellar mass, environment does play a role in shaping present-day passive galaxies. [ABSTRACT FROM AUTHOR]

We explore local and global dynamical differences between the kinematics of ionized gas and stars in a sample of galaxies from Data Release 3 of the SAMI Galaxy Survey. We find better agreement between local (i.e. comparing on a spaxel-to-spaxel basis) velocities and dispersion of gas and stars in younger systems as with previous work on the asymmetric drift in galaxies, suggesting that the dynamics of stars and ionized gas are initially coupled. The intrinsic scatter around the velocity and dispersion relations increases with increasing stellar age and mass, suggesting that subsequent mechanisms, such as internal processes, divergent star formation, and assembly histories, also play a role in setting and altering the dynamics of galaxies. The global (flux-weighted) dynamical support of older galaxies is hotter than in younger systems. We find that the ionized gas in galaxies is almost always dynamically colder than the stars with a steeper velocity gradient. In absolute terms, the local difference in velocity dispersion is more pronounced than the local difference in velocity, possibly reflecting inherent differences in the impact of turbulence, inflow and/or feedback on gas compared to stars. We suggest how these findings may be taken into account when comparing high and low redshift galaxy samples to infer dynamical evolution. [ABSTRACT FROM AUTHOR]

We study environmental quenching using the spatial distribution of current star formation and stellar population ages with the full SAMI Galaxy Survey. By using a star formation concentration index [ C -index, defined as log10(r 50, H α/ r 50, cont)], we separate our sample into regular galaxies (C -index ≥−0.2) and galaxies with centrally concentrated star formation (SF-concentrated; C -index <−0.2). Concentrated star formation is a potential indicator of galaxies currently undergoing 'outside-in' quenching. Our environments cover ungrouped galaxies, low-mass groups (M 200 ≤ 1012.5M⊙), high-mass groups (M 200 in the range 1012.5–14 M⊙) and clusters (M 200 > 1014M⊙). We find the fraction of SF-concentrated galaxies increases as halo mass increases by 9 ± 2 per cent, 8 ± 3 per cent, 19 ± 4 per cent, and 29 ± 4 per cent for ungrouped galaxies, low-mass groups, high-mass groups, and clusters, respectively. We interpret these results as evidence for 'outside-in' quenching in groups and clusters. To investigate the quenching time-scale in SF-concentrated galaxies, we calculate light-weighted age (Age L) and mass-weighted age (Age M) using full spectral fitting, as well as the D n4000 and H δA indices. We assume that the average galaxy age radial profile before entering a group or cluster is similar to ungrouped regular galaxies. At large radius (1–2 R e), SF-concentrated galaxies in high-mass groups have older ages than ungrouped regular galaxies with an age difference of 1.83 ± 0.38 Gyr for Age L and 1.34 ± 0.56 Gyr for Age M. This suggests that while 'outside-in' quenching can be effective in groups, the process will not quickly quench the entire galaxy. In contrast, the ages at 1–2 R e of cluster SF-concentrated galaxies and ungrouped regular galaxies are consistent (difference of 0.19 ± 0.21 Gyr for Age L, 0.40 ± 0.61 Gyr for Age M), suggesting the quenching process must be rapid. [ABSTRACT FROM AUTHOR]

In this work, we investigate how the central stellar metallicity ([Z/H]) of 1363 galaxies from the SAMI galaxy survey is related to their stellar mass and a proxy for the gravitational potential, |$\Phi = \log _{10}\left(\frac{M_*}{M_{\odot }} \right) - \log _{10}\left(\frac{r_e}{\mathrm{kpc}} \right)$|⁠. In agreement with previous studies, we find that passive and star-forming galaxies occupy different areas of the [Z/H]– M * plane, with passive galaxies having higher [Z/H] than star-forming galaxies at fixed mass (a difference of 0.23 dex at log10(M */M⊙) = 10.3). We show for the first time that all galaxies lie on the same relation between [Z/H] and Φ, and show that the offset in [Z/H] between passive and star-forming galaxies at fixed Φ is smaller than or equal to the offset in [Z/H] at fixed mass (an average Δ[Z/H] of 0.11 dex at fixed Φ compared to 0.21 dex at fixed mass). We then build a simple model of galaxy evolution to explain and understand our results. By assuming that [Z/H] traces Φ over cosmic time and that the probability that a galaxy quenches depends on both its mass and size, we are able to reproduce these offsets in stellar metallicity with a model containing instantaneous quenching. We therefore conclude that an offset in metallicity at fixed mass cannot by itself be used as evidence of slow quenching processes, in contrast to previous studies. Instead, our model implies that metal-rich galaxies have always been the smallest objects for their mass in a population. Our findings reiterate the need to consider galaxy size when studying stellar populations. [ABSTRACT FROM AUTHOR]

We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, |$\lambda _{R_{\rm {e}}}$|⁠ , drawn from the SAMI Galaxy Survey. We fit a global |$[\alpha /\rm {Fe}]$| –σ relation, finding that |${[\alpha /\rm {Fe}]}=(0.395\pm 0.010)\rm {log}_{10}(\sigma)-(0.627\pm 0.002)$|⁠. We observe an anti-correlation between the residuals |$\Delta [\alpha /\rm {Fe}]$| and the inclination-corrected |$\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}$|⁠ , which can be expressed as |${\Delta [\alpha /\rm {Fe}]}=(-0.057\pm 0.008){\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}}+(0.020\pm 0.003)$|⁠. The anti-correlation appears to be driven by star-forming galaxies, with a gradient of |${\Delta [\alpha /\rm {Fe}]}\sim (-0.121\pm 0.015){\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}}$|⁠ , although a weak relationship persists for the subsample of galaxies for which star formation has been quenched. We take this to be confirmation that disc-dominated galaxies have an extended duration of star formation. At a reference velocity dispersion of 200 km s−1, we estimate an increase in half-mass formation time from ∼0.5 Gyr to ∼1.2 Gyr from low- to high- |$\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}$| galaxies. Slow rotators do not appear to fit these trends. Their residual α-enhancement is indistinguishable from other galaxies with |${\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}}\lessapprox 0.4$|⁠ , despite being both larger and more massive. This result shows that galaxies with |${\lambda _{\, R_{\rm {e}}}^{\rm {\, eo}}}\lessapprox 0.4$| experience a similar range of star formation histories, despite their different physical structure and angular momentum. [ABSTRACT FROM AUTHOR]

The kinematic morphology–density relation of galaxies is normally attributed to a changing distribution of galaxy stellar masses with the local environment. However, earlier studies were largely focused on slow rotators; the dynamical properties of the overall population in relation to environment have received less attention. We use the SAMI Galaxy Survey to investigate the dynamical properties of ∼1800 early and late-type galaxies with log (M ⋆/ M ⊙) > 9.5 as a function of mean environmental overdensity (Σ5) and their rank within a group or cluster. By classifying galaxies into fast and slow rotators, at fixed stellar mass above log (M ⋆/ M ⊙) > 10.5, we detect a higher fraction (∼3.4σ) of slow rotators for group and cluster centrals and satellites as compared to isolated-central galaxies. We find similar results when using Σ5 as a tracer for environment. Focusing on the fast-rotator population, we also detect a significant correlation between galaxy kinematics and their stellar mass as well as the environment they are in. Specifically, by using inclination-corrected or intrinsic |$\lambda _{R_{\rm {e}}}$| values, we find that, at fixed mass, satellite galaxies on average have the lowest |$\lambda _{\, R_{\rm {e}},\rm {intr}}$|⁠ , isolated-central galaxies have the highest |$\lambda _{\, R_{\rm {e}},\rm {intr}}$|⁠ , and group and cluster centrals lie in between. Similarly, galaxies in high-density environments have lower mean |$\lambda _{\, R_{\rm {e}},\rm {intr}}$| values as compared to galaxies at low environmental density. However, at fixed Σ5, the mean |$\lambda _{\, R_{\rm {e}},\rm {intr}}$| differences for low and high-mass galaxies are of similar magnitude as when varying Σ5 (⁠|$\Delta \lambda _{\, R_{\rm {e}},\rm {intr}} \sim 0.05$|⁠ , with σrandom = 0.025, and σ syst < 0.03). Our results demonstrate that after stellar mass, environment plays a significant role in the creation of slow rotators, while for fast rotators we also detect an independent, albeit smaller, impact of mass and environment on their kinematic properties. [ABSTRACT FROM AUTHOR]

The existence of a kinematic morphology–density relation remains uncertain, and instead stellar mass appears the more dominant driver of galaxy kinematics. We investigate the dependence of the stellar spin parameter proxy on environment using a marked cross-correlation method with data from the Sydney Australian Astronomical Observatory Multi-object Integral-field Spectrograph (SAMI) Galaxy Survey. Our sample contains 710 galaxies with spatially resolved stellar velocity and velocity dispersion measurements. By utilizing the highly complete spectroscopic data from the Galaxy and Mass Assembly Survey, we calculate marked cross-correlation functions for SAMI galaxies using a pair count estimator and marks based on stellar mass and. We detect an anticorrelation of stellar kinematics with environment at the 3.2σ level, such that galaxies with low values are preferably located in denser galaxy environments. However, a significant correlation between stellar mass and environment is also found (correlation at 2.4σ), as found in previous works. We compare these results to mock observations from the cosmological Evolution and Assembly of Galaxies and their Environments (EAGLE) simulations, where we find a similar significant anticorrelation with environment, and a mass and environment correlation. We demonstrate that the environmental correlation of is not caused by the mass–environment relation. The significant relationship between and environment remains when we exclude slow rotators. The signals in SAMI and EAGLE are strongest on small scales (10–100 kpc) as expected from galaxy interactions and mergers. Our work demonstrates that the technique of marked correlation functions is an effective tool for detecting the relationship between and environment. [ABSTRACT FROM AUTHOR]

Large galaxy samples from multiobject integral field spectroscopic (IFS) surveys now allow for a statistical analysis of the z ∼ 0 galaxy population using resolved kinematic measurements. However, the improvement in number statistics comes at a cost, with multiobject IFS survey more severely impacted by the effect of seeing and lower signal-to-noise ratio. We present an analysis of ∼1800 galaxies from the SAMI Galaxy Survey taking into account these effects. We investigate the spread and overlap in the kinematic distributions of the spin parameter proxy |$\lambda _{R_{\rm {e}}}$| as a function of stellar mass and ellipticity ε e. For SAMI data, the distributions of galaxies identified as regular and non-regular rotators with kinemetry show considerable overlap in the |$\lambda _{R_{\rm {e}}}$| – ε e diagram. In contrast, visually classified galaxies (obvious and non-obvious rotators) are better separated in |$\lambda _{R_{\rm {e}}}$| space, with less overlap of both distributions. Then, we use a Bayesian mixture model to analyse the observed |$\lambda _{R_{\rm {e}}}$| –log (M ⋆/M⊙) distribution. By allowing the mixture probability to vary as a function of mass, we investigate whether the data are best fit with a single kinematic distribution or with two. Below log (M ⋆/M⊙) ∼ 10.5, a single beta distribution is sufficient to fit the complete |$\lambda _{R_{\rm {e}}}$| distribution, whereas a second beta distribution is required above log (M ⋆/M⊙) ∼ 10.5 to account for a population of low- |$\lambda _{R_{\rm {e}}}$| galaxies. While the Bayesian mixture model presents the cleanest separation of the two kinematic populations, we find the unique information provided by visual classification of galaxy kinematic maps should not be disregarded in future studies. Applied to mock-observations from different cosmological simulations, the mixture model also predicts bimodal |$\lambda _{R_{\rm {e}}}$| distributions, albeit with different positions of the |$\lambda _{R_{\rm {e}}}$| peaks. Our analysis validates the conclusions from previous, smaller IFS surveys, but also demonstrates the importance of using selection criteria for identifying different kinematic classes that are dictated by the quality and resolution of the observed or simulated data. [ABSTRACT FROM AUTHOR]

We investigate the stellar populations of passive spiral galaxies as a function of mass and environment, using integral field spectroscopy data from the Sydney-AAO Multi-object Integral field spectrograph Galaxy Survey. Our sample consists of 52 cluster passive spirals and 18 group/field passive spirals, as well as a set of S0s used as a control sample. The age and [Z/H] estimated by measuring Lick absorption line strength indices both at the center and within 1Re do not show a significant difference between the cluster and the field/group passive spirals. However, the field/group passive spirals with log(M⋆/M⊙) ≳ 10.5 show decreasing [α/Fe] along with stellar mass, which is ∼0.1 dex smaller than that of the cluster passive spirals. We also compare the stellar populations of passive spirals with S0s. In the clusters, we find that passive spirals show slightly younger age and lower [α/Fe] than the S0s over the whole mass range. In the field/group, stellar populations show a similar trend between passive spirals and S0s. In particular, [α/Fe] of the field/group S0s tend to be flattening with increasing mass above log(M⋆/M⊙) ≳ 10.5, similar to the field/group passive spirals. We relate the age and [α/Fe] of passive spirals to their mean infall time in phase space; we find a positive correlation, in agreement with the prediction of numerical simulations. We discuss the environmental processes that can explain the observed trends. The results lead us to conclude that the formation of the passive spirals and their transformation into S0s may significantly depend on their environments. [ABSTRACT FROM AUTHOR]

We investigate the stellar kinematics of the bulge and disk components in 826 galaxies with a wide range of morphology from the Sydney-AAO Multi-object Integral-field spectroscopy Galaxy Survey. The spatially resolved rotation velocity (V) and velocity dispersion (σ) of bulge and disk components have been simultaneously estimated using the penalized pixel fitting (ppxf) method with photometrically defined weights for the two components. We introduce a new subroutine of ppxf for dealing with degeneracy in the solutions. We show that the V and σ distributions in each galaxy can be reconstructed using the kinematics and weights of the bulge and disk components. The combination of two distinct components provides a consistent description of the major kinematic features of galaxies over a wide range of morphological types. We present Tully–Fisher and Faber–Jackson relations showing that the galaxy stellar mass scales with both V and σ for both components of all galaxy types. We find a tight Faber–Jackson relation even for the disk component. We show that the bulge and disk components are kinematically distinct: (1) the two components show scaling relations with similar slopes, but different intercepts; (2) the spin parameter λ R indicates bulges are pressure-dominated systems and disks are supported by rotation; and (3) the bulge and disk components have, respectively, low and high values in intrinsic ellipticity. Our findings suggest that the relative contributions of the two components explain, at least to first order, the complex kinematic behaviour of galaxies. [ABSTRACT FROM AUTHOR]

We examine the stellar population radial gradients (age, metallicity, and [α/Fe]) of 96 passive central galaxies up to ∼2 Re in the SAMI Galaxy Survey. The targeted groups have a halo mass range of. The main goal of this work is to determine whether central galaxies have different stellar population properties when compared to similarly massive satellite galaxies. For the whole sample, we find negative metallicity radial gradients, which show evidence of becoming shallower with increasing stellar mass. The age and [α/Fe] gradients are slightly positive and consistent with zero, respectively. The [α/Fe] gradients become more negative with increasing mass, while the age gradients do not show any significant trend with mass. We do not observe a significant difference between the stellar population gradients of central and satellite galaxies at fixed stellar mass. The mean metallicity gradients are for central galaxies and for satellites. The mean age and [α/Fe] gradients are consistent between central and satellite galaxies, within the uncertainties, with a mean value of for centrals and for satellites and for centrals and for satellites. The stellar population gradients of central and satellite galaxies show no difference as a function of halo mass. This evidence suggests that the inner regions of central passive galaxies form in a similar fashion to those of satellite passive galaxies, in agreement with a two-phase formation scenario. [ABSTRACT FROM AUTHOR]

We use data from the Sydney-AAO Multi-object Integral-field spectroscopy (SAMI) Galaxy Survey to study the dynamical scaling relation between galaxy stellar mass M ∗ and the general kinematic parameter |$S_K = \sqrt{K V_{\rm rot}^2 + \sigma ^2}$| that combines rotation velocity V rot and velocity dispersion σ. We show that the log  M ∗ – log  SK relation: (1) is linear above limits set by properties of the samples and observations; (2) has slightly different slope when derived from stellar or gas kinematic measurements; (3) applies to both early-type and late-type galaxies and has smaller scatter than either the Tully–Fisher relation (log  M ∗ − log  V rot) for late types or the Faber–Jackson relation (log  M ∗ − log σ) for early types; and (4) has scatter that is only weakly sensitive to the value of K , with minimum scatter for K in the range 0.4 and 0.7. We compare SK to the aperture second moment (the 'aperture velocity dispersion') measured from the integrated spectrum within a 3-arcsecond radius aperture (⁠|$\sigma _{3^{\prime \prime }}$|⁠). We find that while SK and |$\sigma _{3^{\prime \prime }}$| are in general tightly correlated, the log  M ∗ − log  SK relation has less scatter than the |$\log M_* - \log \sigma _{3^{\prime \prime }}$| relation. [ABSTRACT FROM AUTHOR]

We present the second major release of data from the Sydney – Australian Astronomical Observatory Multi-Object Integral Field Spectrograph (SAMI) Galaxy Survey. Data Release Two includes data for 1559 galaxies, about 50 per cent of the full survey. Galaxies included have a redshift range 0.004 < |$z$| < 0.113 and a large stellar mass range 7.5 < log (M ⋆/M⊙) < 11.6. The core data for each galaxy consist of two primary spectral cubes covering the blue and red optical wavelength ranges. For each primary cube, we also provide three spatially binned spectral cubes and a set of standardized aperture spectra. For each core data product, we provide a set of value-added data products. This includes all emission line value-added products from Data Release One, expanded to the larger sample. In addition, we include stellar kinematic and stellar population value-added products derived from absorption line measurements. The data are provided online through Australian Astronomical Optics' Data Central. We illustrate the potential of this release by presenting the distribution of |${\sim } 350\, 000$| stellar velocity dispersion measurements from individual spaxels as a function of R / R e, divided in four galaxy mass bins. In the highest stellar mass bin [log (M ⋆/M⊙) > 11], the velocity dispersion strongly increases towards the centre, whereas below log (M ⋆/M⊙) < 10 we find no evidence for a clear increase in the central velocity dispersion. This suggests a transition mass around log (M ⋆/M⊙) ∼ 10 for galaxies with or without a dispersion-dominated bulge. [ABSTRACT FROM AUTHOR]

In galaxy clusters, efficiently accreting active galactic nuclei (AGNs) are preferentially located in the infall regions of the cluster projected phase-space, and are rarely found in the cluster core. This has been attributed to both an increase in triggering opportunities for infalling galaxies, and a reduction of those mechanisms in the hot, virialized, cluster core. Exploiting the depth and completeness (98 per cent at r < 19.8mag) of the Galaxy And Mass Assembly survey (GAMA), we probe down the group halo mass function to assess whether AGNs are found in the same regions in groups as they are in clusters. We select 451 optical AGNs from 7498 galaxies with log10(M*/M☉) > 9.9 in 695 groups with 11.53⩽log10(M200/M☉)⩽14.56 at z < 0.15. By analysing the projected phase-space positions of these galaxies, we demonstrate that when split both radially and into physically derived infalling and core populations, AGN position within group projected phase-space is dependent on halo mass. For groups with log10(M200/M☉)>13.5,AGNs are preferentially found in the infalling galaxy population with 3.6σ confidence. At lower halo masses, we observe no difference in AGN fraction between core and infalling galaxies. These observations support a model where a reduced number of low-speed interactions, ram pressure stripping and intra-group/cluster medium temperature, the dominance of which increase with halo mass, work to inhibit AGN in the cores of groups and clusters with log10(M200/M☉) > 13.5, but do not significantly affect nuclear activity in cores of less massive structures. [ABSTRACT FROM AUTHOR]