Name: Miriani G. Pastoriza

Institution:Instituto de Fisica, UFRGS

e-mail:miriani.pastoriza(no-spam)ufrgs.br

Partner Contry: BRA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: No

Presentation: Yes

Format: Poster

Title: The basic spectroscopic and photometric data and stellar population analise of the galaxies cluster LCDCS-S001

Co-author: Sandro Barbosa Rembold

Co-authors' Institutions:Universidade Federal do Rio Grande do Sul

Abstract:

The dinamical and populational properties of the high-redshift z=0.7 galaxy cluster LCDCS-S001, are analyzed through imaging and multi object spectroscopy obtained with the GMOS instrument in the Gemini South Observatory. The objects were selected in an i'-band cluster field image, and multi-object spectroscopic observations centered at 7500 angstrons were performed for 40 objects. Spectral features were successfully identified for 20 objects, and used to determine the redshift of the cluster. We found that 12 objects are cluster members and estimate a median redshift of 0.709 for this cluster. The relative velocities of the cluster members were used to estimate the projected cluster mass, which was found to be 3.54 x 10¹⁴M_O. Lick and $D₄₀₀₀ indices were measured and used to determine the stellar population properties of the galaxies, by means of a spectral synthesis through Bruzual & Charlot evolutive models. We found that the bulk of stellar population for the cluster members has a spectrum compatible with solar metallicity and an age betweeen 3.0 and 7.0 Gyrs; with only one exception, the flux contribution of younger <1.0 Gyrs stars in the spectra does not exceed 25% at 4200 angstrons. Emission [OII] lines were detected for 4 galaxies, all of which showing a stronger contribution of young stars compared with other cluster galaxies. The equivalent width of the [OII]λ3727 line was compared with Magris, Bruzual & Binnet models for HII regions. We found good correspondence between our values and the theoretical predictions for solar metallicity and with star formation timescales 1.0 < τ <3.0 Gyrs. In morphological terms we have found that the spheroids map better the structure of the cluster, the disk galaxies populating prefereably the peripherical regions, and we have concluded that around 10% of the cluster of galaxies are spheroids with the tipical effective redius of 10-15 kpc. The bidimensional distribution of the objects shows an alongated morphology of the cluster. Local overdensities identified in the i' image, one of which being part of the cluster, suggests that the cluster is undergoing a fusion processe. This hypotesis is strengthened by the identification of the radio source in the 1.4 GHz at the cluster center, caracteristic of radio halos found in cluster wich undergo dynamical inestabilities.

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