GALEX Observations of "Passive Spirals" in the Cluster Cl 0024+17: Clues to the Formation of S0 Galaxies
Author(s) -
Seán Moran,
Richard S. Ellis,
Tommaso Treu,
Samir Salim,
R. Michael Rich,
G. P. Smith,
JeanPaul Kneib
Publication year - 2006
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/504078
Subject(s) - astrophysics , physics , spiral galaxy , cluster (spacecraft) , star formation , population , galaxy , elliptical galaxy , spiral (railway) , astronomy , galaxy cluster , demography , sociology , computer science , programming language , mathematical analysis , mathematics
We present new results from deep GALEX UV imaging of the cluster Cl 0024+17at z~0.4. Rest-frame far UV emission is detected from a large fraction ofso-called ``passive spiral galaxies'' -a significant population which exhibitsspiral morphology with little or no spectroscopic evidence for ongoing starformation. This population is thought to represent infalling galaxies whosestar formation has been somehow truncated by environmental processes, possiblyin morphological transition to S0 galaxies. Compared to normal cluster spirals,we find that passive spirals are redder in FUV-optical color, while exhibitingmuch stronger UV emission than cluster E/S0s - as expected forrecently-truncated star formation. By modeling the different temporalsensitivities of UV and spectroscopic data to recent activity, we show thatstar formation in passive spirals decayed on timescales of less than 1 Gyr,consistent with `gas starvation' - a process where the cluster environmentprevents cold gas from accreting onto the spiral disk. Intriguingly, thefraction of spirals currently observed in the passive phase is consistent withthe longer period expected for the morphological transformation and thesubsequent build-up of cluster S0s observed since z=0.4.Comment: 5 pages, 3 figures, ApJL accepte
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