GLACE survey: OSIRIS/GTC tuneable filter Hα imaging of the rich galaxy cluster ZwCl 0024.0+1652 at z = 0.395
Résumé
The cores of clusters at 0 ≲
z ≲ 1 are dominated by quiescent early-type
galaxies, whereas the field is dominated by star-forming late-type galaxies. Clusters grow
through the accretion of galaxies and groups from the surrounding field, which implies
that galaxy properties, notably the star formation ability, are altered as they fall into
overdense regions. The critical issues for understanding this evolution are how the
truncation of star formation is connected to the morphological transformation and what
physical mechanism is responsible for these changes. The GaLAxy Cluster Evolution Survey
(GLACE) is conducting a thorough study of the variations in galaxy properties (star
formation, AGN activity, and morphology) as a function of environment in a representative
and well-studied sample of clusters. To address these questions, the GLACE survey is
making a deep panoramic survey of emission line galaxies (ELG), mapping a set of optical
lines ([O ii], [O iii], Hβ andHα/[N ii] when possible) in several galaxy
clusters at z ~
0.40, 0.63, and 0.86. Using the tunable filters (TF) of the OSIRIS
instrument at the 10.4 m GTC telescope, the GLACE survey applies the technique of TF
tomography: for each line, a set of images are taken through the OSIRIS TF, each image
tuned at a different wavelength (equally spaced), to cover a rest frame velocity range of
several thousand km s-1 centred on the mean cluster redshift, and scanned for
the full TF field of view of an 8 arcmin diameter. Here we present the first results of
the GLACE project, targeting the Hα/[N ii] lines in the
intermediate-redshift cluster ZwCl 0024.0+1652 at z = 0.395. Two pointings
have been performed that cover ~2 × rvir. We discuss the specific techniques
devised to process the TF tomography observations in order to generate the catalogue of
cluster Hα
emitters, which contains more than 200 sources down to a star formation rate
(SFR) ≲1 M⊙/yr. An
ancillary broadband catalogue is constructed, allowing us to discriminate line interlopers
by means of colour diagnostics. The final catalogue contains 174 unique cluster sources.
The AGN population is distinguished using different diagnostics and found to be
~37% of the ELG
population. The median SFR of the star-forming population is 1.4 M⊙/yr. We
studied the spatial distribution of ELG and confirm the existence of two components in the
redshift space. Finally, we exploited the outstanding spectral resolution of the TF,
attempting to estimate the cluster mass from ELG dynamics, finding M200 = (4.1 ± 0.2) × 1014 M⊙
h-1, in agreement with previous weak-lensing estimates.
| Origine | Publication financée par une institution |
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