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

Abstract

We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to test whether these mergers can generate S0 galaxies with kinematics intermediate between fast and slow rotators. We find that minor mergers induce a lower decrease of the global rotational support 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 ${\epsilon }_{\mathrm{e}}\sim 0.8$. 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 $0.4<{\epsilon }_{\mathrm{e}}<0.7$. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to decrease slightly its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and decrease significantly its intrinsic ellipticity. The remnant bulges remain nearly spherical ($B/A\sim C/A>0.9$), but exhibit a wide range of triaxialities ($0.20<T<1.00$). In the plane of global anisotropy of velocities ($\delta$) vs. intrinsic ellipticity (${\epsilon }_{\mathrm{e},\mathrm{intr}}$), some of our models extend the linear trend found in previous major merger simulations towards higher ${\epsilon }_{\mathrm{e},\mathrm{intr}}$ values, while others depart from it. 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. The different trends exhibited by ellipticals and S0 galaxies in the $\delta$ - ${\epsilon }_{\mathrm{e}}$ diagram may be pointing to the different role played by major mergers in the build-up of each morphological type.

Corrected typos. 20 pages, 14 figures. Accepted for publishing in A&A

References in corpus (19)

• The SAURON project -- IX. A kinematic classification for early-type galaxies
• The SAURON project -- X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics
• COLD GASS, an IRAM legacy survey of molecular gas in massive galaxies: I. Relations between H2, HI, stellar content and structural properties
• Kinematic Structure of Merger Remnants
• Strangulation in Galaxy Groups
• Multiple minor mergers: formation of elliptical galaxies and constraints for the growth of spiral disks
• A Wide-field Survey of Two Z~0.5 Galaxy Clusters: Identifying the Physical Processes Responsible for the Observed Transformation of Spirals into S0s
• 2-Dimensional Kinematics of Simulated Disc Merger Remnants
• Growth of galactic bulges by mergers. II. Low-density satellites
• Bars, ovals and lenses in early-type disk galaxies: probes of galaxy evolution
• SAURON's Challenge for the Major Merger Scenario of Elliptical Galaxy Formation
• Measuring the fading of S0 galaxies using globular clusters
• A giant bar induced by a merger event at z=0.4?
• The formation of S0 galaxies: evidence from globular clusters
• A forming, dust enshrouded disk at z=0.43: the first example of a late type disk rebuilt after a major merger?
• Line-of-sight velocity distributions of elliptical galaxies from collisionless mergers
• Galaxy mergers at high resolution: From elliptical galaxies to tidal dwarfs and globular clusters
• Old stellar counter-rotating components in early-type galaxies from elliptical-spiral mergers
• Secular Evolution in Disk Galaxies: The Growth of Pseudobulges and Problems for Cold Dark Matter Galaxy Formation

Cited by in corpus (13)

• The SAMI Galaxy Survey: the link between angular momentum and optical morphology
• Formation of S0 galaxies through mergers. Bulge-disc structural coupling resulting from major mergers
• Formation of S0 galaxies through mergers. V. Antitruncated stellar discs resulting from major mergers
• Formation of S0 galaxies through mergers. Evolution in the Tully-Fisher relation since $z\sim 1$
• X-shooter Spectroscopy and HST Imaging of 15 Ultra Massive Quiescent Galaxies at $z\gtrsim 2$
• Accretion of Galaxy Groups into Galaxy Clusters
• The SLUGGS survey: Using extended stellar kinematics to disentangle the formation histories of low mass S0 galaxies
• Star formation quenching imprinted on the internal structure of naked red nuggets
• A feather on the hat: Tracing the giant stellar stream around the Sombrero galaxy
• Bar rejuvenation in S0 galaxies?
• The Fundamental Plane of Massive Quiescent Galaxies at z~2
• Observations of cold gas and star formation in dwarf S0 galaxies
• The structure of stellar disks in isolated lenticular galaxies