Bibcode
Poggianti, Bianca M.; Fasano, Giovanni; Bettoni, Daniela; Cava, Antonio; Dressler, A.; Vanzella, E.; Varela, Jesus; Couch, Warrick J.; D'Onofrio, Mauro; Fritz, Jacopo; Kjaergaard, Per; Moles, Mariano; Valentinuzzi, T.
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 697, Issue 2, pp. L137-L140 (2009).
Fecha de publicación:
6
2009
Número de citas
105
Número de citas referidas
100
Descripción
We quantify the evolution of the spiral, S0 and elliptical fractions in
galaxy clusters as a function of cluster velocity dispersion (σ)
and X-ray luminosity (LX ) using a new database of 72 nearby
clusters from the Wide-Field Nearby Galaxy-Cluster Survey (WINGS)
combined with literature data at z = 0.5-1.2. Most WINGS clusters have
σ between 500 and 1100 km s-1, and LX
between 0.2 and 5 × 1044 erg s-1. The S0
fraction in clusters is known to increase with time at the expense of
the spiral population. We find that the spiral and S0 fractions have
evolved more strongly in lower σ, less massive clusters, while we
confirm that the proportion of ellipticals has remained unchanged. Our
results demonstrate that morphological evolution since z = 1 is not
confined to massive clusters, but is actually more pronounced in
low-mass clusters, and therefore must originate either from secular
(intrinsic) evolution and/or from environmental mechanisms that act
preferentially in low-mass environments, or both in low- and high-mass
systems. We also find that the evolution of the spiral fraction
perfectly mirrors the evolution of the fraction of star-forming
galaxies. Interestingly, at low-z the spiral fraction anticorrelates
with LX . Conversely, no correlation is observed with
σ. Given that both σ and LX are tracers of the
cluster mass, these results pose a challenge for current scenarios of
morphological evolution in clusters.
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