Abstract
We present deep GMOS long-slit spectroscopy of 15 Coma cluster S0 galaxies,
and extract kinematic properties along the major axis to several times the disc
scale-length. Supplementing our dataset with previously published data, we
create a combined sample of 29 Coma S0s, as well as a comparison sample of 38
Coma spirals. Using photometry from SDSS and 2MASS, we construct the
Tully-Fisher relation (TFR; luminosity versus maximum rotational velocity) for
S0 galaxies. At fixed rotational velocity, the Coma S0 galaxies are on average
fainter than Coma spirals by 1.10$\pm$0.18, 0.86$\pm$0.19 and 0.83$\pm$0.19 mag
in the g, i and Ks bands respectively. The typical S0 offsets remain unchanged
when calculated relative to large field-galaxy spiral samples. The observed
offsets are consistent with a simple star formation model in which S0s are
identical to spirals until abrupt quenching occurs at some intermediate
redshift. The offsets form a continuous distribution tracing the time since the
cessation of star formation, and exhibit a strong correlation (>6\sigma) with
residuals from the optical colour-magnitude relation. Typically, S0s which are
fainter than average for their rotational velocity are also redder than average
for their luminosity. The S0 TFR offset is also correlated with both the
projected cluster-centric radius and the \Sigma (projected) local density
parameter. Since current local environment is correlated with time of accretion
into the cluster, our results support a scenario in which transformation of
spirals to S0s is triggered by cluster infall.
Users
Please
log in to take part in the discussion (add own reviews or comments).