Overview
The Dark Energy Survey will investigate the dynamics of the universe and the large-scale structure using four techniques. The first one consists in the observation of the light curves of Type Ia supernovae. According to the accepted theory, a Type Ia supernova is an explosion of a white dwarf star that orbits around a companion star, caused by the accretion of mass from the companion star, which makes it unstable, starting, as a consequence, a gigantic thermonuclear explosion. For cosmology, these events are important because they are very bright, which allows astronomers to detect them at very large distance, and their luminosity distance can be inferred by the observation of their light curves. Finally, the standard model of cosmology, which is based on some assumptions that includes the validity of General Relativity and the large scale homogeneity and isotropy of our universe, predicts that astronomers can constrain the properties of the expansion of the universe based on the observation of the luminosity distance and the redshift from far away type IA supernova.
The other three techniques that Dark Energy Survey will use to constrain the properties of the expansion and the large scale structure of our universe are Baryon Acoustic Oscillations, Counts of Galaxy Cluster and Weak Lensing. In contrast to type IA supernova luminosity distance measures, these probes allow scientists to understand simultaneously the expansion of the universe and the evolution of the dark matter density field perturbations. These perturbations were indispensable to the formation of galaxies and galaxy clusters. Basically, the standard model of cosmology assumes that quantum fluctuations of the density field of the various components that were present when our universe was very young were, somehow, enhanced through a very rapid expansion called inflation. After that, gravitational collapse makes this initial fluctuation bigger and bigger, allowing baryons to fall into the gravitational potential field of more dense regions of space in order to form galaxies. Nevertheless the growth rate of these dark matter halos is sensitive to the dynamics of the expansion of the universe and the Dark Energy Survey will use this connection to probe the properties of that expansion.
The new camera that will be installed at the Victor M. Blanco Telescope by DES collaboration will bring new observational possibilities, which are not available for the current surveys, like, for instance, the Sloan Digital Sky Survey. One significant difference between the current CCD at the Victor M. Blanco Telescope and the DECam is the quantum efficiency in the red part of the visible spectra and in the near infrared. While the former has high quantum efficiency for blue light and a significant lower sensitivity for wavelengths located in the near infrared, the latter was designed to have its maximum sensitivity for red light. This is a very important property for the observation of very distant sources, like type IA supernovae or galaxy cluster, because the expansion of the universe redshift the photons emitted from a given source. On the other hand, Silicon, which is the main element used to make CCDs, becomes transparent for infrared light, and this issue made the development of the DECam's CCD a technological challenge.
The DES collaboration is led by Josh Frieman and composed of many research institutes and universities. Inside the United States, The Fermi National Accelerator Laboratory (Fermilab), the University of Chicago, the National Optical Astronomy Observatory, the Ohio State University, the Texas A&M University, the University of Illinois at Urbana-Champaign, the Lawrence Berkeley National Laboratory, the University of Michigan, the University of Pennsylvania, the Argonne National Laboratory, the University of California Santa Cruz, the SLAC National Accelerator Laboratory and the Stanford University are involved in this project. In addition, the Brazilian Center for Physics Research (Centro Brasileiro de Pesquisas Físicas - CBPF), the National Observatory (Observatório Nacional - ON) and the Federal University of Rio Grande do Sul (Universidade Federal do Rio Grande do Sul - UFRGS) are the Brazilian institutes involved.
The British institutions that are participating in the DES collaboration are the University College London, the University of Cambridge, the University of Edinburgh, the University of Portsmouth, the University of Sussex and the University of Nottingham. Moreover, the Cluster for Excellence for Fundamental Physics and the Ludwig-Maximilians University of Munich (Ludwig-Maximilians Universität) are the German institutes affiliated. Finally, the Institute of Space Sciences (Instituto de Ciencias del Espacio), the Institute of High Energy Physics (Institut de Fisica d'Altes Energies) and the Center for Energy, Environment and Technology Research (Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas - CIEMAT) are the Spanish institutes involved.
Finally, due to the complexity of the science involved in the Dark Energy Survey, the scientist that participate in this project were divided in many working groups. Currently the working groups are: the weak lensing working group, the clusters working group, the large scale structure working group, the supernova working group, the galaxy evolution working group and the Strong Lensing working group. There is also people working on simulations, observing and survey strategy, calibration, photometric redshift, data challenges, quasars and the mechanical, electronic and optical development of the DECam. Every year there is an annual meeting between all groups in order to release new results about the development of the project. Besides that, the collaboration has a website, where scientist can release new results, presentations and articles. Some of the releases in this website are open for the general public.
Read more about this topic: The Dark Energy Survey