Bibcode
Sánchez-Blázquez, P.; Gibson, B. K.; Kawata, D.; Cardiel, N.; Balcells, M.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 400, Issue 3, pp. 1264-1282.
Fecha de publicación:
12
2009
Número de citas
24
Número de citas referidas
21
Descripción
We present a spectral analysis of a sample of red-sequence galaxies
identified by van Dokkum as dry merger remnants and ongoing dry mergers.
Kinematics, stellar population absorption features and ionization from
emission lines are derived. We find that approximately half of the
sample showing strong tidal features have younger stellar populations
than a control sample at a given velocity dispersion. Conversely,
galaxies with weak tidal tails and/or ongoing mergers - with the
exception of one galaxy - do not show this young component. This seems
to indicate that the young stellar populations observed in a significant
fraction of ellipticals is the consequence of star formation triggered
by mergers. This young component is consistent with a light `frosting'
of young stars (<2 per cent by mass) superimposed upon a dominant,
old (~11 Gyr), stellar population. In terms of stellar populations,
these mergers are, in fact, fairly dry. We found, however, that merger
remnants with young stellar populations are supported by rotation,
contrary to the expectations of a major dry merger. This suggests that
the small amount of gas involved has been sufficient to produce a
dynamically cold stellar component. Half of the galaxies with strong
tidal distortion, however, are slow rotating and have stellar
populations compatible with the control sample at a given velocity
dispersion. Remarkably, none of the galaxies with velocity dispersions
in excess of 250kms-1 (the putative transition between dry
and wet mergers) has a young stellar component, independent of the
merger stage.
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