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Title: THE MYSTERY OF THE σ-BUMP—A NEW SIGNATURE FOR MAJOR MERGERS IN EARLY-TYPE GALAXIES?

The stellar velocity dispersion as a function of the galactocentric radius of an early-type galaxy can generally be well approximated by a power law σ∝r {sup β}. However, some observed dispersion profiles show a deviation from this fit at intermediate radii, usually between one and three R {sub eff}, where the velocity dispersion remains constant with radius, showing a bump-like behavior, which we term the {sup σ-}bump. To understand the origin of this σ-bump, we study a set of simulated early-type galaxies formed in major mergers. We find the σ-bump in all of our simulated early-type galaxies, with the size and position of the bump slightly varying from galaxy to galaxy, suggesting that the bump is a characteristic of the major merger formation scenario. The feature can be seen both in the intrinsic and projected stellar velocity dispersions. In contrast to shells that form during the merger event but evolve with time and finally disappear, the σ-bump stays nearly constant with radius and is a permanent feature that is preserved until the end of the simulation. The σ-bump is not seen in the dark matter and gas components and we therefore conclude that it is a purely stellar feature ofmore » merger remnants.« less
Authors:
; ;  [1] ;  [2]
  1. Universitäts-Sternwarte München, Scheinerstrasse 1, D-81679 München (Germany)
  2. Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland)
Publication Date:
OSTI Identifier:
22365981
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 783; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COMPUTERIZED SIMULATION; GALACTIC EVOLUTION; GALAXIES; NONLUMINOUS MATTER; VELOCITY