Formation of S0 galaxies through mergers

Eliche‐Moral, M. C.; Rodríguez-Pérez, Cristina; Borlaff, Alejandro; Querejeta, Miguel; Tapia, Trinidad

doi:10.1051/0004-6361/201832911

Cited by 72 publications

(71 citation statements)

References 271 publications

(213 reference statements)

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“…This paper was a proof of concept that major mergers can produce disc galaxies in the idealized scenario of two isolated galaxies, and allowed to study and follow in detail and in a controlled environment the formation of the disc. Similar work then followed, such as Tapia et al (2017), Eliche-Moral et al (2018) and Sauvaget et al (2018), who confirmed these results. However, such simulations are run in isolation, therefore they neglect the effect of the environment, and make assumptions on the parameters of the merger such as the orbit, or on the structures of the two merging galaxies.…”

Section: Introductionsupporting

confidence: 68%

Disc galaxies formed from major mergers in Illustris

Peschken

Łokas

Athanassoula

2020

Monthly Notices of the Royal Astronomical Society

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We show how wet major mergers can create disc galaxies in a cosmological context, using the Illustris simulation. We select a sample of 38 disc galaxies having experienced a major merger in their history with no subsequent significant minor merger, and study how they transform into discs after the merger. In agreement with what was previously found in controlled simulations of such mergers, we find that their disc is built gradually from young stars formed after the merger in the disc region, while the old stars born before the merger form an ellipsoidal component. Focusing on one fiducial case from our sample, we show how the gas was initially dispersed in the halo region right after the merger, but is then accreted onto a disc to form stars, and builds the disc component. We then select a sample of major mergers creating elliptical galaxies, to show that those cases correspond mainly to dry mergers, where the lack of star formation prevents the formation of a disc in the remnant galaxy. The amount of gas in the remnant galaxy after the merger is therefore essential to determine the final outcome of a major merger.

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Section: Introductionsupporting

confidence: 68%

Disc galaxies formed from major mergers in Illustris

Peschken

Łokas

Athanassoula

2020

Monthly Notices of the Royal Astronomical Society

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“…In addition, extensive irregular regions of dust extending about 6 kpc along the semimajor axis of the galaxy are observed. These structures, together with the presence of a disk of gas rotating in the opposite direction to the stellar component of the galaxy, provide evidence of a merger/interaction event in the recent past with an object of lower mass than NGC 4546 (Eliche-Moral et al 2018). In this context, the presence of the young NGC 4546-UCD1 with an age of ∼ 4 Gyr and with a rotation direction similar to the gas distribution, would be related to the aforementioned interaction event.…”

Section: Discussionmentioning

confidence: 80%

Field/isolated lenticular galaxies with high SN values: the case of NGC 4546 and its globular cluster system

Escudero

Faifer

Castelli

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present a photometric study of the field lenticular galaxy NGC 4546 using Gemini/GMOS imaging in g ′ r ′ i ′ z ′ . We perform a 2D image decomposition of the surface brightness distribution of the galaxy using GALFIT, finding that four components adequately describe it. The subtraction of this model from our images and the construction of a colour map allow us to examine in great detail the asymmetric dust structures around the galactic centre. In addition, we perform a detailed analysis of the globular cluster (GC) system of NGC 4546. Using a Gaussian Mixture Model algorithm in the colour-colour plane we detected hints of multiple groups of GC candidates: the classic blue and red subpopulations, a group with intermediate colours that present a concentrated spatial distribution towards the galaxy, and an additional group towards the red end of the colour distribution. We estimate a total GC population for NGC 4546 of 390 ± 60 members and specific frequency S N = 3.3 ± 0.7, which is relatively high compared to the typical value for galaxies of similar masses and environment. We suggest that the unusual GC population substructures were possibly formed during the interaction that led to the formation of the young ultra-compact dwarf (NGC 4546-UCD1) found in this system. Finally, we estimate the distance modulus of NGC 4546 by analyzing its luminosity function, resulting in (m − M ) = 30.75 ± 0.12 mag (14.1 Mpc).

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“…The current paradigm for galaxy formation, in particular of ETG, details the hierarchical assembly of massive galaxies via the merging of smaller systems, which result in expectedly pressure-supported systems due to the nature of the merging process (for instance, see Somerville & Davé 2015, and references therein for a general review). Merging during the lifetime of a galaxy is a key aspect, and often the focus, of many cosmological and/or hydrodynamical simulations (for example, see Bird et al 2013;Athanassoula et al 2016;Eliche-Moral et al 2018). Moreover, merging is often invoked to explain many phenomena seen in observational studies (for example, see Arnold et al 2011;Lidman et al 2013;Guérou et al 2016).…”

Section: Implications For the Formation History Of Ngc 3115mentioning

confidence: 99%

Combining stellar populations with orbit-superposition dynamical modelling: the formation history of the lenticular galaxy NGC 3115

Poci

McDermid

Zhu

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a combination of the Schwarzschild orbit-superposition dynamical modelling technique with the spatially-resolved mean stellar age and metallicity maps to uncover the formation history of galaxies. We apply this new approach to a remarkable 5-pointing mosaic of VLT/MUSE observations obtained by Guérou et al. (2016) extending to a maximum galactocentric distance of ∼ 120 (5.6 kpc) along the major axis, corresponding to ∼ 2.5 R e . Our method first identifies 'families' of orbits from the dynamical model that represent dynamicallydistinct structures of the galaxy. Individual ages and metallicities of these components are then fit for using the stellar-population information. Our results highlight components of the galaxy that are distinct in the combined stellar dynamics/populations space, which implies distinct formation paths. We find evidence for a dynamically-cold, metal-rich disk, consistent with a gradual in-situ formation. This disk is embedded in a generally-old population of stars, with kinematics ranging from dispersion-dominated in the centre to an old, diffuse, metal-poor stellar halo at the extremities. We find also a direct correlation between the dominant dynamical support of these components, and their associated age, akin to the relation observed in the Milky Way. This approach not only provides a powerful model for inferring the formation history of external galaxies, but also paves the way to a complete population-dynamical model.

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Formation of S0 galaxies through mergers

Cited by 72 publications

References 271 publications

Disc galaxies formed from major mergers in Illustris

Disc galaxies formed from major mergers in Illustris

Field/isolated lenticular galaxies with high SN values: the case of NGC 4546 and its globular cluster system

Combining stellar populations with orbit-superposition dynamical modelling: the formation history of the lenticular galaxy NGC 3115

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