Properties of Early-type, Dry Galaxy Mergers and the Origin of Massive, Slowly Rotating, Pressure Supported Elliptical Galaxies
نویسندگان
چکیده
The luminosity dependence of kinematical and isophotal properties of elliptical galaxies is investigated using numerical simulations of galaxy merging, combined with semi-analytical models of hierarchical structure formation. Mergers of spiral galaxies as the only formation mechanism for elliptical galaxies can neither reproduce the kinematical and photometric properties of very massive elliptical galaxies nor the change from rotation supported disky to pressure supported boxy systems with increasing luminosity. Semi-analytical models indicate that the most massive galaxies assemble in major mergers of early-type progenitors even at low redshifts. We present numerical simulations showing that binary mergers of early-type galaxies open an additional channel for the formation of pressure supported, slowly rotating and boxy ellipticals. Including this channel in the semi-analytical models we can successfully reproduce the observed trend that more luminous giant ellipticals are more boxy and pressure supported. This trend can be strengthened by suppressing residual gas infall and star formation for galaxies with stellar bulge masses M∗ ≥ 3 × 10 M⊙. Hence we propose that mergers of early-type galaxies play an important role for the assembly of massive elliptical galaxies. Subject headings: galaxies: elliptical – galaxies: interaction– galaxies: structure – galaxies: evolution – methods: numerical
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Properties of Early-type, Dry Galaxy Mergers and the Origin of Massive Elliptical Galaxies
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