Regrowth of stellar discs in mature galaxies: the two-component nature of NGC 7217 revisited with VIRUS-W

Fabricius, Maximilian; Coccato, L.; Bender, Ralf; Drory, Niv; Gössl, Claus; Landriau, Martin; Saglia, R.; Thomas, Jens; Williams, Michael J.

doi:10.1093/mnras/stu694

Cited by 28 publications

(33 citation statements)

References 100 publications

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“…In the cases where the disentangling of the components is successful, there is typically a substantial difference in stellar populations, and, even if co-rotating, a substantial difference in kinematics (e.g. Johnston et al 2013;Fabricius et al 2014). In this case, as is shown below, there seems to be no age difference between the prograde and retrograde kinematics components, while there is a certain difference in the metallicity.…”

Section: ′′mentioning

confidence: 95%

Unveiling the counter-rotating nature of the kinematically distinct core in NGC 5813 with MUSE

Krajnović

Weilbacher

Urrutia

et al. 2015

Mon. Not. R. Astron. Soc.

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MUSE observations of NGC 5813 reveal a complex structure in the velocity dispersion map, previously hinted by SAURON observations. The structure is reminiscent of velocity dispersion maps of galaxies comprising two counter-rotating discs, and may explain the existence of the kinematically distinct core (KDC). Further evidence for two counter-rotating components comes from the analysis of the higher moments of the stellar line-of-sight velocity distributions and fitting MUSE spectra with two separate Gaussian line-of-sight velocity distributions. The emission-line kinematics show evidence of being linked to the present cooling flows and the buoyant cavities seen in Xrays. We detect ionised gas in a nuclear disc-like structure, oriented like the KDC, which is, however, not directly related to the KDC. We build an axisymmetric Schwarzschild dynamical model, which shows that the MUSE kinematics can be reproduced well with two counter-rotating orbit families, characterised by relatively low angular momentum components, but clearly separated in integral phase space and with radially varying contributions. The model indicates that the counter-rotating components in NGC 5813 are not thin discs, but dynamically hot structures. Our findings give further evidence that KDCs in massive galaxies should not necessarily be considered as structurally or dynamically decoupled regions, but as the outcomes of the mixing of different orbital families, where the balance in the distribution of mass of the orbital families is crucial. We discuss the formation of the KDC in NGC 5813 within the framework of gas accretion, binary mergers and formation of turbulent thick discs from cold streams at high redshift.

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Section: ′′mentioning

confidence: 95%

Unveiling the counter-rotating nature of the kinematically distinct core in NGC 5813 with MUSE

Krajnović

Weilbacher

Urrutia

et al. 2015

Mon. Not. R. Astron. Soc.

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“…For example Fabricius et al (2014) show that kinematics of the intermediate-type galaxy NGC 7217 clearly separates into two components one with high dispersion (the bulge) and the second with low dispersion (the disk). These components are consistent with a photometric bulge-disk decomposition.…”

Section: Definition Of a Bulgementioning

confidence: 99%

“…Bulges with n b < 2 are observed to have higher fractions (and surface density) of gas (Fisher et al, 2013), that is more actively forming stars Gadotti, 2009;Fisher & Drory, 2010), and has more disk-like kinematics (Fabricius et al, 2014) when compared to bulges with n b > 2. These results, and those in Fig.…”

Section: Using Sérsic Index To Identify Bulge Typesmentioning

confidence: 99%

An Observational Guide to Identifying Pseudobulges and Classical Bulges in Disc Galaxies

Fisher¹,

Drory²

2016

Astrophysics and Space Science Library

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In this review our aim is to summarize the observed properties of pseudobulges and classical bulges. We utilize an empirical approach to studying the properties of bulges in disk galaxies, and restrict our analysis to statistical properties. A clear bimodality is observed in a number of properties including morphology, structural properties, star formation, gas content & stellar population, and kinematics. We conclude by summarizing those properties that isolate pseudobulges from classical bulges. Our intention is to describe a practical, easy to use, list of criteria for identifying bulge types.

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“…The fitting procedure is described in Fabricius et al (2014), and it extends the maximum penalized likelihood method by Gebhardt et al (2000) to treat nebular emissions. After fitting and removing the continuum with a third-degree polynomial, we fitted the wavelength range from 4905−5325 Å.…”

Section: Shape Of the Line-of-sight Velocity Distributionsmentioning

confidence: 99%

Properties and formation mechanism of the stellar counter-rotating components in NGC 4191

Coccato

Fabricius

Morelli

et al. 2015

A&A

Self Cite

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Aims. We here distinguish two counter-rotating stellar components in NGC 4191 and characterize their physical properties such as kinematics, morphology, age, and metallicity. Methods. We obtained integral field spectroscopic observations with VIRUS-W and used a spectroscopic decomposition technique to separate the contribution of two stellar components to the observed galaxy spectrum. We also performed a photometric decomposition, modeling the galaxy with a Sérsic bulge and two exponential disks of different scale length, with the aim of associating these structural components with the kinematic components. We then measured the equivalent width of the absorption line indices on the best-fit models that represent the kinematic components and compared our measurements to the predictions of stellar population models that also account for the variable abundance ratio of α elements. Results. We have evidence that the line-of-sight velocity distributions (LOSVDs) are bimodal and asymmetric, consistent with the presence of two distinct kinematic components. The combined information of the intensity of the peaks of the LOSVDs and the photometric decomposition allows us to associate the Sérsic bulge and the outer disk with the main kinematic component and to associate the inner disk with the secondary kinematic component. We find that the two kinematic stellar components counter-rotate with respect to each other. The main component is the most luminous and massive; the secondary component rotates along the same direction as the ionized gas. The study of the stellar populations reveals that the two kinematic components have the same solar metallicity and subsolar abundance ratio, without significant radial gradients. On the other hand, their ages show negative gradients and the possible indication that the secondary component is the younger. We interpret our results in light of recent cosmological simulations and suggest gas accretion along two filaments as the formation mechanism of the stellar counter-rotating components in NGC 4191.

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Regrowth of stellar discs in mature galaxies: the two-component nature of NGC 7217 revisited with VIRUS-W

Cited by 28 publications

References 100 publications

Unveiling the counter-rotating nature of the kinematically distinct core in NGC 5813 with MUSE

Unveiling the counter-rotating nature of the kinematically distinct core in NGC 5813 with MUSE

An Observational Guide to Identifying Pseudobulges and Classical Bulges in Disc Galaxies

Properties and formation mechanism of the stellar counter-rotating components in NGC 4191

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