Name: Natalia Verônica Boris

Institution: IAG-USP

e-mail: natalia(no-spam)astro.iag.usp.br

Partner Contry: BRA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: Yes

Presentation: Yes

Format: Poster

Title: Photomety of Four Fields Around Quasar Pairs at z ∼ 1

Co-author: (1) Laerte Sodré Jr., (2) Eduardo Cypriano

Co-authors' Institutions: (1) IAG - USP, (2) Department of Physics and Astronomy - University College London

Abstract:

We have studied the photometric properties of four fields around the high-redshift quasar pairs QP1310 0007, QP1355-0032, QP0110-0219, and QP0114-3140 at z ∼ 1 with the aim of identifying large-scale structures- galaxy clusters or groups- around them. This sample was observed with GMOS in Gemini North and South telescopes in the g', r', i', and z' bands, and our photometry is complete to a limiting magnitude of i' ∼ 24 mag (corresponding to ∼ M_i'^∗2 at the redshift of the pairs). First, we have estimated the photometric redshifts of galaxies with an empirical method, which uses a locally weighted regression algorithm. With this method, the redshift error is 0.16 per galaxy. Then, we have analyzed the redshift interval z_pair ± 0.16, finding a significant overdensity in all fields. In the fields QP1310 0007, QP1355-0032, and QP0110-0219, the galaxy projected distribution results more concentrated than in a random one. With an analogous of the Abell richness criterion, three of our fields resulted rich (QP1355-0032, QP0110-0219, and QP0114-3140). The fields around the pairs QP1310 0007 and QP0110-0219 show an excess of red galaxies (1.7 σ and 3.3 σ respectively). These fields also show a clustered or filament-like distribution. Our analysis suggests that QP1310 0007, QP1355-0032 and QP0110-0219 are probably in rich clusters environments. For the pair QP0114-3140 the evidence for existence of a galaxy cluster at the pair redshift is less compeling.