The SAMI Galaxy Survey: rules of behaviour for spin-ellipticity radial tracks in galaxies

Rawlings, Alexander; Foster, Caroline; Sande, Jesse van de; Taranu, Dan S.; Croom, S. M.; Bland-Hawthorn, Joss; Brough, Sarah; Bryant, Julia J.; Colless, Matthew; Lagos, Claudia del P.; Konstantopoulos, I. S.; Lawrence, Jon; López-Sánchez, Á. R.; Lorente, Nuria P. F.; Medling, Anne M.; Oh, Sree; Owers, Matt S.; Richards, Samuel N.; Scott, Nicholas; Sweet, Sarah M.; Yi, Sukyoung K.

doi:10.1093/mnras/stz2797

Cited by 6 publications

(2 citation statements)

References 53 publications

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“…be changed by altering 𝜆 𝑅 start or the gradient of the dividing line, and so we reject this selection effect as the driver behind our results. An additional factor that must be considered is that the SAMI sample is known to contain a non-zero number of galaxies with counter-rotating disks (Rawlings et al 2020), also referred to as 2𝜎 galaxies. When integrated over a wide enough aperture, these will have a low measured spin proxy due to the summation of the separate disk components, and may be misidentified as SRs.…”

Section: Physical Implicationsmentioning

confidence: 99%

The SAMI Galaxy Survey: The Link Between [$α$/Fe] and Kinematic Morphology

Watson,

Davies,

van de Sande

et al. 2022

Preprint

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We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, 𝜆 𝑅 e , drawn from the SAMI Galaxy Survey. We fit a global [𝛼/Fe]-𝜎 relation, finding that [𝛼/Fe] = (0.395 ± 0.010)log 10 (𝜎) − (0.627 ± 0.002). We observe an anti-correlation between the residuals Δ [𝛼/Fe] and the inclination-corrected 𝜆 eo 𝑅 e , which can be expressed as Δ [𝛼/Fe] = (−0.057 ± 0.008)𝜆 eo 𝑅 e + (0.020 ± 0.003). The anti-correlation appears to be driven by star-forming galaxies, with a gradient of Δ [𝛼/Fe] ∼ (−0.121 ± 0.015)𝜆 eo 𝑅 e , although a weak relationship persists for the subsample of galaxies for which star formation has been quenched. We take this to be confirmation that disk-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-𝜆 eo 𝑅 e galaxies. Slow rotators do not appear to fit these trends. Their residual 𝛼-enhancement is indistinguishable from other galaxies with 𝜆 eo 𝑅 e 0.4, despite being both larger and more massive. This result shows that galaxies with 𝜆 eo 𝑅 e 0.4 experience a similar range of star formation histories, despite their different physical structure and angular momentum.

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Section: Physical Implicationsmentioning

confidence: 99%

The SAMI Galaxy Survey: The Link Between [$α$/Fe] and Kinematic Morphology

Watson,

Davies,

van de Sande

et al. 2022

Preprint

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“…Photometric decomposition is usually performed using open-source software tools: e.g., IRAF, GALFIT (Peng et al 2010), or PROFIT (Robotham et al 2017). While photometric decomposition is often based on profile fitting, Zhu et al (2018a) and Santucci et al (2022) attempted to conduct kinematic decomposition using integral field spectroscopic data, e.g., CALIFA and SAMI (González Delgado et al 2015;Sánchez et al 2016b;van de Sande et al 2017;Rawlings et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Translators of Galaxy Morphology Indicators between Observation and Simulation

Dubois

et al. 2023

ApJ

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Based on the recent advancements in numerical simulations of galaxy formation, we anticipate the achievement of realistic models of galaxies in the near future. Morphology is the most basic and fundamental property of galaxies, yet observations and simulations still use different methods to determine galaxy morphology, making it difficult to compare them. We hereby perform a test on the recent NewHorizon simulation, which has spatial and mass resolutions that are remarkably high for a large-volume simulation, to resolve the situation. We generate mock images for the simulated galaxies using SKIRT, which calculates complex radiative transfer processes in each galaxy. We measure morphological and kinematic indicators using photometric and spectroscopic methods following observers’ techniques. We also measure the kinematic disk-to-total ratios using the Gaussian mixture model and assume that they represent the true structural composition of galaxies. We found that spectroscopic indicators such as V/σ and λ R closely trace the kinematic disk-to-total ratios. In contrast, photometric disk-to-total ratios based on the radial profile fitting method often fail to recover the true kinematic structure of galaxies, especially small ones. We provide translating equations between various morphological indicators.

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Formation of counter-rotating stars during gas-rich disc–disc mergers

Martel

Simon

2020

Monthly Notices of the Royal Astronomical Society

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We present a new scenario for the origin of the counter-rotating stars in disc galaxies, defined as stars that have a negative tangential velocity. This scenario involves a merger between two gas-rich disc galaxies that have comparable masses, are nearly co-planar, and are rotating in the same direction. The merger results in an intense starburst, during which a significant fraction of the gas is converted to stars. The system then settles into an equilibrium configuration consisting of a thick disc and a bulge partly supported by velocity dispersion and a thin disc supported by rotation. Star formation proceeds until most of the gas supply is exhausted. Stars formed during the starburst have tangential velocities ranging from −600 km s−1 to 600 km s−1. Stars formed afterward in the thick disc and bulge have high eccentricities and low tangential velocities, typically in the range −100 km s−1 to 100 km s−1, while stars formed in the thin disc have large, positive velocities. All fast, counter-rotating stars (V < −200 km s−1) are old, metal-poor, with very low dispersion in ages and metallicities. By contrast, fast, co-rotating stars (V > 200 km s−1) have a wide range of ages and metallicities. The average abundances ratios $\rm [O/H]$ and [Fe/H] for fast, co-rotating stars typically exceed the corresponding ratios for fast, counter-rotating stars by 0.1 dex to 0.4 dex, while the dispersion in the values of NFe/NH are larger by factors between 2 and 14. This provides an observational signature of major, gas-rich mergers at high redshift.

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The SAMI Galaxy Survey: rules of behaviour for spin-ellipticity radial tracks in galaxies

Cited by 6 publications

References 53 publications

The SAMI Galaxy Survey: The Link Between [$α$/Fe] and Kinematic Morphology

The SAMI Galaxy Survey: The Link Between [$α$/Fe] and Kinematic Morphology

Translators of Galaxy Morphology Indicators between Observation and Simulation

Formation of counter-rotating stars during gas-rich disc–disc mergers

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