NOAO >   Observing Info >   Approved Programs >   2011B-0353

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Proposal Information for 2011B-0353


PI: Rodrigo Carrasco, Gemini Observatory - South, rcarrasco@gemini.edu
Address: Gemini Observatory, Colina El Pino s/n, La Serena, Chile

CoI: Brenda Frye, University of San Francisco
CoI: Dan Coe, Space Telescope Science Institute
CoI: Renato Dupke, Observatorio Nacional (ON/MCT)
CoI: Julian Merten, University of Heidelberg
CoI: Laerte Sodre, Universidade de Sao Paulo
CoI: Richard Massey, University of Edinburgh
CoI: Filberto Braglia, University of British Columbia
CoI: Eduardo Cypriano, Universidade de Sao Paulo
CoI: Adi Zitrin, Tel Aviv University, Israel
CoI: Jessica Krick, Spitzer Science Center, USA
CoI: Narciso Benitez, Instituto de Astrofisica de Andalucia (CSIC), Spain

Title: Constraining the Mass of the Spectacular Pandora's Cluster, Abell 2744

Abstract: Violent cluster mergers provide a unique opportunity to study the interplay between dark matter (DM) and ICM and to set constraints on the nature of DM. In particular, cluster mergers near first core passage allow us to ``see'' DM by comparing the spatial distribution of the intra-cluster gas (baryonic) to that of DM. We have recently finished a lensing analysis of the particularly interesting merging system, A2744, the Pandora cluster. We found that it is the result of a spectacular merging event, significantly more complex than the "Bullet Cluster", that produced a wide variety of new phenomenologies, among them, a Bullet, a Dark sub-cluster (no gas), a Ghost sub-cluster (no DM), which can provide fundamental insights to the physics of the ICM, and begs further observations. Our analyses revealed 34 arcs produced by strong gravitational lensing, none of which had been published to date. Spectroscopic redshifts of these arcs are essential to determine precise masses of the main merging system providing crucial information for further numerical simulations and to set stronger constraints on the DM self-interaction cross-section. Therefore we are requesting 17.2 hours on Gemini+GMOS-S, primarily to obtain spectroscopic redshifts of multiply strongly lensed arcs produced by this impressive cluster.


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NOAO >   Observing Info >   Approved Programs >   2011B-0353

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