Scientific Objectives
The study of the Large Scale Structure (LSS) of the Universe attempts to address the following open questions in cosmology:
- What is the dark matter, and which is its detailed contribution to the energy content of the Universe?
- What is the dark energy, and how it affects the dynamics of the Universe?
- Do fundamental constants vary along the history of the Universe?
In order to contribute to the possible answer to those questions, in this project we will use several large scale structure probes:
- The distribution and large-scale clustering of the galaxies, and its evolution with time. The matter power spectrum (P(k)) and the two-point correlation function (ξ(r)) contain certain geometric features associated to some characteristic length-scales in the Universe, as the horizon at matter-radiation equality, or the acoustic horizon at last scattering. In particular, the latter determines the Baryon Acoustic Oscillation (BAO) scale.
- The distribution of the big voids in the Universe. Both the statistics of big voids, as well as the characterization of the void expansion, provides a complementary tool to determine the matter density and the equation of state of the dark energy.
- The distribution and abundance of galaxy clusters, as well as the evolution with time. Among other parameters, the cluster mass function depends both on the matter density as well as in the amplitude of the power spectrum. The time evolution of the mass function n(M,z) is also govern by the growth of structures in the Universe, thus being also sensitive to the equation of state of the dark energy.
- The ISW (integrated Sachs-Wolfe) effect. The accelerated expansion of the Universe, due to the dark energy, originates a decay of the large-scale gravitational potential wells in the local Universe (z<1). This effect is characterized by the presence of a non-zero correlation between the number density of galaxies, and the temperature of the CMB at large scales (above few degrees).
- Observables (e.g. spectral features) which permit us to trace the variability of the fundamental constants.
In this project, we will use, among others results, the catalogue of galaxy clusters obtained by the Planck satellite and the results of the BOSS (SDSS-III) survey. Moreover, we will participate in the DESI project, and we will start the activities related with the scientific exploitation of the future EUCLID satellite (ESA).
In addition to these observational activities, from a theoretical point of view, we will work with the properties of the large scale structure and in different environments, to understand the contributions of the dark matter and dark energy to the formation and evolution of the structures. We will develop analytical models and will compare them with hydrodynamical simulations and large surveys, in order to understand the physical processes that determine the clustering of the baryonic matter.
Finally, this project contains some aspects related to instrumental developments, in relation with the IAC participation in the EUCLID satellite and the DESI project. EUCLID is a ESA mission, which was recently approved within the Cosmic Vision 2020-2025 programme, and aims a high-precision survey mission to map the geometry of the Dark Universe with demonstrated feasibility and high precision. The satellite will be launch in 2019, and will have two instruments, one imaging instrument with a visible channel (VIS), and an infrared instrument (NISP) with a imaging channel and a spectroscopic channel. The IAC will contribute with the development of the Instrument Control Unit (ICU) of NISP. In this particular aspect, we collaborate with the Universidad Politécnica de Cartagena (UPCT). DESI (Dark Energy Spectroscopic Instrument) will measure the effect of dark energy on the expansion of the universe. It will obtain optical spectra for tens of millions of galaxies and quasars, constructing a 3-dimensional map spanning the nearby universe to 10 billion light years. The IAC will contribute with the fabrication of the focal plate unit of the instrument.