Combining quasars and galaxies to trace large-scale structure

• Grant number: 15/11442-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): December 01, 2015
• Effective date (End): May 31, 2020
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Luis Raul Weber Abramo
• Grantee: Carolina Queiroz de Abreu Silva
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 12/00800-4 - The 3-D universe: astrophysics with large galaxy surveys, AP.TEM
• Associated scholarship(s): 19/06766-1 - Selection of Quasar candidates based on multi-band photometric data, BE.EP.DR

Abstract

Galaxies and quasars are the main extragalactic byproducts of surveys such as the Sloan Digital Sky Survey (I-II-III), WiggleZ, J-PAS, etc. However, the near-degeneracy of quasars with stars in color-color and color-magnitude plots makes it very hard to identify those objects with broad-band imaging, which is how SDSS and WiggleZ can target quasars. However, there is now a concrete possibility of mapping a massive number of quasars, over a large area, with the narrow-band optical survey J-PAS. During the M.Sc. project of the student, Carolina Queiroz, we optimized the widely used photometric redshift and typing codes BPZ (Benítez 2000) and LePhare (Arnouts et al. 1999; Ilbert et al. 2006) to identify AGNs (type I and II), and to distinguish them from stars and unresolved galaxies. A Bayesian technique was employed to help break the degeneracies that arise, and can degrade the quality of the catalogs through both misidentification and catastrophic redshift errors. On the other hand, during two other parallel M.Sc. projects (by Lucas F. Secco and Arthur M. Loureiro) we developed the method to do the Fourier analysis of multi-tracer cosmological surveys. The method was tested and validated on simulated data, and the results were collected in the paper arXiv: 1505.04106. The field is now ripe for a joint analysis of galaxies and quasars, both in more realistic simulations (namely, N-body simulations with semi-analytical recipes for halo occupation distributions of different types of objects) and in existing cosmological surveys (in particular, the photometric and spectroscopic SDSS catalog). Finally, the ongoing A-PLUS survey will also detect millions of galaxies and quasars over a wide range of redshifts, and over a large area (more than 14,000 square degrees). The survey should be completed in around three years, which makes it an ideal case to employ the experience we will accumulate during the period of this Ph.D. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

BONOLI, S.; MARIN-FRANCH, A.; VARELA, J.; VAZQUEZ RAMIO, H.; ABRAMO, L. R.; CENARRO, A. J.; DUPKE, R. A.; VILCHEZ, J. M.; CRISTOBAL-HORNILLOS, D.; GONZALEZ DELGADO, R. M.; et al. The miniJPAS survey: A preview of the Universe in 56 colors. Astronomy & Astrophysics, v. 653, SEP 3 2021. (18/05392-8, 11/18729-1, 15/11442-0, 17/02375-2)

NAKAZONO, L.; DE OLIVEIRA, C. MENDES; HIRATA, N. S. T.; JERAM, S.; QUEIROZ, C.; EIKENBERRY, STEPHEN S.; GONZALEZ, A. H.; ABRAMO, R.; OVERZIER, R.; ESPADOTO, M.; et al. On the discovery of stars, quasars, and galaxies in the Southern Hemisphere with S-PLUS DR2. Monthly Notices of the Royal Astronomical Society, v. 507, n. 4, p. 5847-5868, NOV 2021. (18/09165-6, 19/06766-1, 19/10923-5, 15/22308-2, 19/26492-3, 18/20977-2, 14/10566-4, 19/01312-2, 18/25671-9, 19/23388-0, 17/25835-9, 15/11442-0, 16/12331-0)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

SILVA, Carolina Queiroz de Abreu. Photometric redshifts of quasars in narrow-band surveys. 2021. Doctoral Thesis - Universidade de São Paulo (USP). Instituto de Física (IF/SBI) São Paulo.