Interpreting asymmetric line profiles in merger remnants

Balcells, M.
Bibliographical reference

Astronomy and Astrophysics (ISSN 0004-6361), vol. 249, no. 2, Sept. 1991, p. L9-L12.

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Absorption line profile asymmetries in ellipticals with peculiar core kinematics, and their role as diagnostics of mergers, are analyzed using self-consistent numerical merger models. The remnants of mergers involving a denser secondary component show asymmetric line-of-sight velocity distributions at their cores. Skewness is negative where the rotation curve is positive and positive where the rotation curve is negative, in close agreement with observations. In the models, the asymmetry is not due to a disk of accreted secondary material; it is intrinsic to the distribution of primary particles, and has been added during the merger. It is argued that the asymmetries are a consequence of the transfer of the orbital energy and angular momentum to the primary particles during the merger; for the mergers studied here, profile asymmetries are a relic of the formation dynamics rather than the signature of superimposed components.