A giant bar induced by a merger event at <i>z</i> = 0.4?

Peirani, Sébastien; Hammer, F.; Flores, H.; Yang, Yanbin; Athanassoula, E.

doi:10.1051/0004-6361/200810760

Cited by 45 publications

(56 citation statements)

References 41 publications

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“…This means that it must be difficult to quantify the effects of each mechanism separately. Additionally, recent observations have reported the existence of some S0s that clearly derive from major merger events in which the disc-rebuilding has been successful, so this mechanism cannot be ignored even though the properties of present-day S0s seem too relaxed and smooth to have been formed through a mechanism as violent as a major merger (Peirani et al 2009;Yang et al 2009;Hammer et al 2009aHammer et al ,b, 2010. In fact, many studies find that major mergers may have played a key role in the definitive build-up of the bulk of the massive ETG population (both ellipticals and S0s) in low-to-intermediate density environments at 0.6 < z < 1, in agreement with standard hierarchical models of galaxy formation (see Eliche-Moral et al 2010a,b;Bernardi et al 2011b,a;Prieto et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Tapia

Eliche‐Moral

Balcells

et al. 2014

A&A

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Context. Numerical studies have shown that the properties of the S0 galaxies with kinematics intermediate between fast and slow rotators are difficult to explain by a scenario of major mergers. Aims. We investigate whether the smoother perturbation induced by minor mergers can reproduce these systems. Methods. We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to determine the structural and kinematic evolution induced by the encounters. The original primary galaxies represent gas-poor fast-rotator S0b and S0c galaxies with high intrinsic ellipticities. The original bulges are intrinsically spherical and have low rotation. Different mass ratios, parent bulges, density ratios, and orbits were studied. Results. Minor mergers induce a lower decrease of the global rotational support (as provided by λ e ) than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to e ∼ 0.8. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at 0.4 < e < 0.7. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to slightly decrease its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and significantly decrease its intrinsic ellipticity. The remnant bulges remain nearly spherical (B/A ∼ C/A > 0.9), but exhibit a wide range of triaxialities (0.20 < T < 1.00). In the plane of global anisotropy of velocities (δ) vs. intrinsic ellipticity ( e,intr ), some of our models extend the linear trend found in previous major merger simulations towards higher e,intr values, while others clearly depart from it (depending on the progenitor S0). This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. Conclusions. The smoother changes induced by minor mergers can explain the existence of S0s with intermediate kinematic properties between fast and slow rotators that are difficult to explain with major mergers. The different trends exhibited by ellipticals and S0 galaxies in the δ -e diagram may be pointing to the different role played by major mergers in the build-up of each morphological type.

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Section: Discussionmentioning

confidence: 99%

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Tapia

Eliche‐Moral

Balcells

et al. 2014

A&A

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“…Some proposed mechanisms for forming bars are, e.g., mergers and interactions. These processes can create both the bar and the bulge, in particular in those galaxies with early type morphologies (see, e.g., Walker et al 1996;Berentzen et al 2004;Peirani et al 2009). During the formation of the bulge, the star formation could have been enhanced by the presence of this bar, increasing the metallicity and the [E/Fe] values of the bulge with respect to those bulges lacking this structure (e.g.…”

Section: Summary and Discussionmentioning

confidence: 99%

Study of stellar populations in the bulges of barred galaxies

Pérez

Sánchez‐Blázquez

2011

A&A

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Aims. We wish to determine the influence of bars on the building of galaxy bulges through analysis of ages and metallicities derived from stellar absorption line-strength indices. Methods. Long-slit spectroscopy was obtained for a sample of 20 early-type barred galaxies. Line-strength indices were measured and used to derive age and metallicity gradients in the bulge region by comparing them with stellar population models. The same analysis was carried out with similar data for unbarred galaxies taken from the literature. Results. The bulges of barred galaxies seem to be more metal rich, at a given velocity dispersion (σ), than the bulges of unbarred galaxies, as measured by a few metallicity sensitive indices. There are indications that the ratio of relative abundance of alpha elements with respect to iron, [E/Fe], derived for the bulges of barred galaxies tend to lie above the values of the unbarred galaxies at a given σ. The metallicity gradients for the majority of the bulges are negative so less metal-rich towards the end of the bulge. The gradient values show a large scatter for galaxies with σ below 150 km s −1 . The age distribution is related to the presence of a bulge substructure, such as a nuclear ring or an inner disk. The metallicity of both the bulge and the bar are very well correlated, indicating a close link between the enrichment histories of both components. Conclusions. Bulges of barred early type galaxies might have experienced a different chemical enrichment than do the bulges of unbarred galaxies of the same morphological type, the same central velocity dispersion, and low inclination angles. The hinted stellar populations differences separating the bulges of barred and unbarred galaxies and the strong link between the metallicity of the bulge and the presence of a bar points to scenarios where they both form simultaneously in processes that lead to rapid and massive episodes of star formation, possibly linked to the bar formation. To confirm and generalise the results found here, it would be useful to extend the data set to a larger number of unbarred galaxies and a wider range of morphological types

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“…The delta PA for barred galaxies span from 0 to 80 degrees with no peak in the distribution. Peirani et al (2009) find that given specific initial conditions, an interaction between two galaxies having a mass ratio of 1:3 could produce a bar. In view of this result, we can't exclude as interacting objects the barred galaxies that present a misalignment between the optical and kinematic position angles lower than 20 degrees.…”

Section: Morphological and Kinematic Parametersmentioning

confidence: 91%

Kinematics of galaxies in compact groups

Torres-Flores

Oliveira²,

Amram

et al. 2010

A&A

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We obtained new Fabry-Perot data cubes and derived velocity fields, monochromatic, and velocity dispersion maps for 28 galaxies in the Hickson compact groups 37, 40, 47, 49, 54, 56, 68, 79, and 93. We also derived rotation curves for 9 of the studied galaxies, 6 of which are strongly asymmetric. Combining these new data with previously published 2D kinematic maps of compact group galaxies, we investigated the differences between the kinematic and morphological position angles for a sample of 46 galaxies. We find that one third of the unbarred compact group galaxies have position angle misalignments between the stellar and gaseous components. This and the asymmetric rotation curves are clear signatures of kinematic perturbations, probably because of interactions among compact group galaxies. A comparison between the B-band Tully-Fisher relation for compact group galaxies and for the GHASP field-galaxy sample shows that, despite the high fraction of compact group galaxies with asymmetric rotation curves, these lay on the TF relation defined by galaxies in less dense environments, although with more scatter. This agrees with previous results, but now confirmed for a larger sample of 41 galaxies. We confirm the tendency for compact group galaxies at the low-mass end of the Tully-Fisher relation (HCG 49b, 89d, 96c, 96d, and 100c) to have either a magnitude that is too bright for its mass (suggesting brightening by star formation) and/or a low maximum rotational velocity for its luminosity (suggesting tidal stripping). These galaxies are outside the Tully Fisher relation at the 1σ level, even when the minimum acceptable values of inclinations are used to compute their maximum velocities. Including such galaxies with v < 100 km s −1 in the determination of the zero point and slope of the compact group B-band Tully-Fisher relation would strongly change the fit, making it different from the relation for field galaxies, which has to be kept in mind when studying scaling relations of interacting galaxies, especially at high redshifts.

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A giant bar induced by a merger event at z = 0.4?

Cited by 45 publications

References 41 publications

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Study of stellar populations in the bulges of barred galaxies

Kinematics of galaxies in compact groups

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