ESTUDO DE GALÁXIAS EM DOIS CANDIDATOS A PROTOAGLOMERADO EM z > 2 NO COSMOS/ULTRAVISTA COM O GEMINI/GMOS

Abstract

ABSTRACT: Protoclusters of galaxies, the progenitors of high-redshift galaxy clusters, are ideal laboratories to study dark matter assembly and galaxy evolution. However, despite of their importance, only a small and heterogeneous sample of these structures has been detected so far. Chiang et al. (2014) presented a photometric survey in the 1.62 deg2 COSMOS/UltraVISTA field and identified 36 "Coma"-type protocluster candidates at z_phot ~ 1.5 - 3. Our research focused on two of the best candidates, which are located at z_phot = 2.24 and 2.48. Between January 2016 and January 2017, spectroscopic observations of 172 galaxies in these two structures were performed using the Gemini telescopes and the GMOS instruments. In this thesis, we will present the data reduction process and analyze the 1D and 2D spectra of these galaxies. In total, we detected emission lines for 12 of them, and strong continuum for other 24. However, since the S/N ratio of the strong continuum spectra was very low, we could not identify absorption lines in them, so our research consisted in studying the 12 sources for which we found emission lines. We initially estimated their spectroscopic redshifts and compared them with the photometric redshifts from the literature, and analysed their magnitudes. Then, using diagnostic diagrams of UV emission lines rates and X-ray images from the Chandra Observatory, we estimated which of them had active nuclei. Finally, using the fluxes of the emission lines detected, we calculated the star formation rates of these galaxies