Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; U.S. Department of Energy ; U.S. National Science Foundation ; Ministry of Science and Education of Spain ; Science and Technology Facilities Council of the United Kingdom ; Higher Education Fending Council for England ; National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign ; Kavli Institute of Cosmological Physics at the University of Chicago ; Center for Cosmology and Astro-Particle Physics at the Ohio State University ; Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University ; Financiadora de Estudos e Projetos ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Ministerio da Ciencia, Tecnologia e Inovacao ; Deutsche Forschungsgemeinschaft ; Collaborating Institutions in the Dark Energy Survey ; Argonne National Laboratory ; University of California at Santa Cruz ; University of Cambridge ; Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid ; University of Chicago ; University College London ; DES-Brazil Consortium ; University of Edinburgh ; Eidgenossische Technische Hochschule (ETH) Zurich ; Fermi National Accelerator Laboratory ; University of Illinois at Urbana-Champaign ; Institut de Ciencies de l'Espai (IEEC/CSIC) ; Institut de Fisica d'Altes Energies ; Lawrence Berkeley National Laboratory ; Ludwig-Maximilians Universitat Munchen ; associated Excellence Cluster Universe ; University of Michigan ; National Optical Astronomy Observatory ; University of Nottingham ; Ohio State University ; University of Pennsylvania ; University of Portsmouth ; SLAC National Accelerator Laboratory, Stanford University ; University of Sussex ; Texas AM University ; OzDES Membership Consortium ; National Science foundation ; MINECO ; European Union ; CERCA program of the Generalitat de Catalunya ; European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013) ; Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO) ; U.S. Department of Energy, Office of Science, Office of High Energy Physics ; CNPq: 141935/2014-6 ; CNPq: 465376/2014-2 ; National Science foundation: AST-1138766 ; National Science foundation: AST-1536171 ; MINECO: AYA2015-71825 ; MINECO: ESP2015-66861 ; MINECO: FPA2015-68048 ; MINECO: SEV-2016-0588 ; MINECO: SEV-2016-0597 ; MINECO: MDM-2015-0509 ; European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013): 240672 ; European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013): 291329 ; European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013): 306478 ; Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO): CE110001020 ; U.S. Department of Energy, Office of Science, Office of High Energy Physics: DE-AC02-07CH11359 ; We use data from the first-year observations of the DES collaboration to measure the galaxy angular power spectrum (APS), and search for its BAO feature. We test our methodology in a sample of 1800 DES Y1-like mock catalogues. We use the pseudo-C-l, method to estimate the APS and the mock catalogues to estimate its covariance matrix. We use templates to model the measured spectra and estimate template parameters firstly from the G's of the mocks using two different methods, a maximum likelihood estimator and a Markov Chain Monte Carlo, finding consistent results with a good reduced chi(2). Robustness tests are performed to estimate the impact of different choices of settings used in our analysis. Finally, we apply our method to a galaxy sample constructed from DES Y1 data specifically for LSS studies. This catalogue comprises galaxies within an effective area of 1318 deg(2) and 0.6 < z < 1.0. We find that the DES Y1 data favour a model with BAO at the 2.6 sigma C.L. However, the goodness of fit is somewhat poor, with chi(2)/(d.o.f.) = 1.49. We identify a possible cause showing that using a theoretical covariance matrix obtained from C-l's that are better adjusted to data results in an improved value of chi(2)/(dof) = 1.36 which is similar to the value obtained with the real-space analysis. Our results correspond to a distance measurement of D-A (Z(eff) = 0.81)/r(d) = 10.65 +/- 0.49, consistent with the main DES BAO findings. This is a companion paper to the main DES BAO article showing the details of the harmonic space analysis.