Stellar orbits in cosmological galaxy simulations: the connection to formation history and line-of-sight kinematics

Röttgers, Bernhard; Naab, Thorsten; Oser, Ludwig

doi:10.1093/mnras/stu1762

Cited by 47 publications

(72 citation statements)

References 80 publications

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“…The anti-correlation between V/σ and h 3 is one of the crucial differences between galaxies with and without discs (Bender et al 1994;Krajnović et al 2011Krajnović et al , 2013avan de Sande et al 2017). These anti-correlations are typically found in remnants of gas-rich mergers (Bendo & Barnes 2000;Jesseit et al 2005;González-García et al 2006;Naab et al 2006aNaab et al , 2007Jesseit et al 2007;Hoffman et al 2009;Röttgers et al 2014) or in simulations of objects that did not have a strong feedback mechanism turned on (e.g. no AGN feedback Dubois et al 2016;Frigo et al 2019).…”

Section: Local Kinematic Parametersmentioning

confidence: 79%

Formation channels of slowly rotating early-type galaxies

Krajnović

Ural

Küntschner

et al. 2020

A&A

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We study the evidence for a diversity of formation processes in early-type galaxies by presenting the first complete volume-limited sample of slow rotators with both integral-field kinematics from the ATLAS 3D Project and high spatial resolution photometry from the Hubble Space Telescope. Analysing the nuclear surface brightness profiles of 12 newly imaged slow rotators, we classify their light profiles as core-less, and place an upper limit to the core size of about 10 pc. Considering the full magnitude and volumelimited ATLAS 3D sample, we correlate the presence or lack of cores with stellar kinematics, including the proxy for the stellar angular momentum (λ Re ) and the velocity dispersion within one half-light radius (σ e ), stellar mass, stellar age, α-element abundance, and age and metallicity gradients. More than half of the slow rotators have core-less light profiles, and they are all less massive than 10 11 M . Core-less slow rotators show evidence for counter-rotating flattened structures, have steeper metallicity gradients, and a larger dispersion of gradient values (∆[Z/H] = −0.42 ± 0.18) than core slow rotators (∆[Z/H] = −0.23 ± 0.07). Our results suggest that core and core-less slow rotators have different assembly processes, where the former, as previously discussed, are the relics of massive dissipation-less merging in the presence of central supermassive black holes. Formation processes of core-less slow rotators are consistent with accretion of counter-rotating gas or gas-rich mergers of special orbital configurations, which lower the final net angular momentum of stars, but support star formation. We also highlight core fast rotators as galaxies that share properties of core slow rotators (i.e. cores, ages, σ e , and population gradients) and core-less slow rotators (i.e. kinematics, λ Re , mass, and larger spread in population gradients). Formation processes similar to those for core-less slow rotators can be invoked to explain the assembly of core fast rotators, with the distinction that these processes form or preserve cores.

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Section: Local Kinematic Parametersmentioning

confidence: 79%

Formation channels of slowly rotating early-type galaxies

Krajnović

Ural

Küntschner

et al. 2020

A&A

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“…This difference in the kinematic behaviour of fast rotators at large radii is illustrated in Figure 3 of Cappellari (2016), and our observations appear consistent with this general picture. Röttgers et al (2014) have found in their simulations that in-situ and ex-situ formed stars follow similar orbit distributions; as such, it is difficult to rule out late dry accretion from the kinematics alone. However, we note that the λR profiles for our FRs are very similar in shape to those presented in Naab et al (2014), which are based on the same simulations as Röttgers et al (2014), for galaxies that have experienced late (z < 2) gas-rich mergers and/or gradual dissipation.…”

Section: Discussionmentioning

confidence: 97%

Integral-field kinematics and stellar populations of early-type galaxies out to three half-light radii

Boardman

Weijmans

Bosch

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We observed twelve nearby H i-detected early-type galaxies (ETGs) of stellar mass ∼ 10 10 M M * ∼ 10 11 M with the Mitchell Integral-Field Spectrograph, reaching approximately three half-light radii in most cases. We extracted line-of-sight velocity distributions for the stellar and gaseous components. We find little evidence of transitions in the stellar kinematics of the galaxies in our sample beyond the central effective radius, with centrally fast-rotating galaxies remaining fast-rotating and centrally slow-rotating galaxies likewise remaining slow-rotating. This is consistent with these galaxies having not experienced late dry major mergers; however, several of our objects have ionised gas that is misaligned with respect to their stars, suggesting some kind of past interaction. We extract Lick index measurements of the commonly-used Hβ, Fe5015, Mg b, Fe5270 and Fe5335 absorption features, and we find most galaxies to have flat Hβ gradients and negative Mg b gradients. We measure gradients of age, metallicity and abundance ratio for our galaxies using spectral fitting, and for the majority of our galaxies find negative age and metallicity gradients. We also find the stellar mass-to-light ratios to decrease with radius for most of the galaxies in our sample. Our results are consistent with a view in which intermediate-mass ETGs experience mostly quiet evolutionary histories, but in which many have experienced some kind of gaseous interaction in recent times.

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“…GAMA is a large campaign that combines large multi-wavelength photometric data with a spectroscopic survey of ∼300,000 galaxies carried out using the AAOmega multi-object spectrograph on the AAT. Furthermore, targets were selected from eight highdensity cluster regions sampled within radius R 200 with the same stellar mass limit as for the GAMA fields (Owers et al 2017;Bryant et al 2015). The aim of the SAMI Galaxy Survey selection is to cover a broad range in galaxy stellar mass ( * = M 10 10 8 1 2…”

Section: Sami Galaxy Surveymentioning

confidence: 99%

“…For the cluster environment, we use photometry from the SDSS (York et al 2000) and VLT Survey Telescope ATLAS imaging data (Owers et al 2017;Shanks et al 2013). Stellar masses are derived from the rest-frame i-band absolute magnitude and g−i color by using the color-mass relation following the method of Taylor et al (2011).…”

Section: Ancillary Datamentioning

confidence: 99%

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The Sami Galaxy Survey: Revisiting Galaxy Classification Through High-Order Stellar Kinematics

Sande

Bland-Hawthorn

Fogarty

et al. 2017

ApJ

128

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Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the highorder stellar kinematic moments h 3 (∼skewness) and h 4 (∼kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a sample of 315 galaxies, without a morphological selection, using two-dimensional integral field data from the SAMI Galaxy Survey. Proxies for the spin parameter (l R e ) and ellipticity ( e ) are used to separate fast and slow rotators; there exists a good correspondence to regular and non-regular rotators, respectively, as also seen in earlier studies. We confirm that regular rotators show a strong h 3 versus s V anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h 3 and s V . Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h 3 versus s V signatures. Within the SAMI Galaxy Survey, we identify five classes of high-order stellar kinematic signatures using Gaussian mixture models. Class 1 corresponds to slow rotators, whereas Classes 2-5 correspond to fast rotators. We find that galaxies with similar  l R e e -values can show distinctly different s h V 3 -signatures. Class 5 objects are previously unidentified fast rotators that show a weak h 3 versus s V anti-correlation. From simulations, these objects are predicted to be disk-less galaxies formed by gas-poor mergers. From morphological examination, however, there is evidence for large stellar disks. Instead, Class 5 objects are more likely disturbed galaxies, have counter-rotating bulges, or bars in edge-on galaxies. Finally, we interpret the strong anti-correlation in h 3 versus s V as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators.

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Stellar orbits in cosmological galaxy simulations: the connection to formation history and line-of-sight kinematics

Cited by 47 publications

References 80 publications

Formation channels of slowly rotating early-type galaxies

Formation channels of slowly rotating early-type galaxies

Integral-field kinematics and stellar populations of early-type galaxies out to three half-light radii

The Sami Galaxy Survey: Revisiting Galaxy Classification Through High-Order Stellar Kinematics

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