Galactic astronomy is the study of the Milky Way, a barred spiral galaxy containing several structural components. A barred bulge is in the central part extending out to 10 thousand light-years, which harbors a 4 million solar mass black hole in the center surrounded by a nuclear star cluster. Outside the bar, the thin disk extends from 10000 to 50000 light-years, and contains most of the stellar and gaseous mass and most of the star formation activity of the Galaxy. Extragalactic Astronomy studies the structure and evolution of galaxies and the intergalactic medium beyond the Milky Way. This includes a large array of objects ranging from dwarf galaxies, quasars and clusters of galaxies, and spanning the last 13 billion years of the history of the Universe. Extragalactic astronomy is a fertile research ground where many branches of physics (high energy physics, cosmology, hydrodynamics, radiative processes, etc.) converge.
Galactic Astronomy at the ICCUB includes three main lines of research: galaxy modelling, the study of stellar constituents and stellar luminosity calibration. At present, this research is fully influenced by the scientific exploitation of the Gaia mission data, in which ICCUB researchers are deeply involved (see the Gaia UB link for more information). Understanding the Milky Way as a holistic system is one of the key challenges astrophysicists will face in the coming decade. ICCUB’s contribution to galaxy modeling is directed towards a better understanding of the origin and evolution of the large structures in the galactic disk —bar, spirals and warp— and the archaeology of the Milky Way —missing satellites—, through an in-depth investigation of the dynamics and chemistry of the system. This field of research is being revolutionized thanks to the recently published Gaia Data Release 2 (and the future releases) with precise astrometry and photometry for more than 1 billion stars. First results can be found at the science verification papers of Gaia data release 2 here. On the other hand, the study of the stellar constituents of the Galactic disk and halo focuses on two central aspects: 1) where do the stars form and 2)what are their astrophysical properties. The Gaia mission provides us with a detailed interpretation of the phase space data in terms of specific events that have shaped the Milky Way. ICCUB’s contribution is organized around two central goals: a) to provide new insights into the popular scenario that all stars have formed in clusters, i.e. to investigate cluster formation and evolution (our analysis of the DR2 data has already led to a significant revision of our knowledge of galactic clusters, with additions and removals to the list of known clusters), and b) to capitalize on the opportunities that Gaia brings to the study of variable stars’ data.
ICCUB’s interest in Extragalactic Astrophysics extends beyond the Milky Way and is concerned, too, with the formation of the first galaxies, which were formed from pristine matter. They comprised population III stars, which reionised the intergalactic medium, polluted it with metals and left behind the seeds of SMBHs. These are processes currently being modeled at ICCUB. Detailed analytical models and huge numerical simulations are being developed, which make use of the most powerful computational tools presently available. The resulting predictions are confronted with the latest, progressively complete, observations drawn from huge wide angle (all-sky) nearby galaxy surveys (e.g. SDSS, 2dF) as well as very deep, high-redshift, ones (e.g. Hubble Deep Field, GROTH, DEEP2), carried out by means of the new generation of very large ground-based telescopes and sophisticated detectors on board of satellites covering the whole electromagnetic spectrum, from gamma to radio wavelengths. One of the best methods to probe the intergalactic matter out of which galaxies form is through absorption spectra, where we measure the spectrum of light absorbed by intervening matter from a distant luminous source (usually a quasar, or massive black hole accreting matter and emitting a prodigiously bright light). Using these observations, we have studied the distribution of matter in space and of the clouds of gas called Damped Lyman Alpha systems, to relate them to galaxies of different masses in the process of formation.
Gaia is a satellite by the European Space Agency (ESA) designed for astrometry and launched on 2013. The main goal of the Gaia mission is to make the largest, most precise three-dimensional map of our Galaxy by surveying an unprecedented one per cent of its population of 100 billion stars. It has produced two releases of data; Gaia's Data release 1, in September 2016, and Gaia's second data release in April, 2018 .
ICCUB researchers have a leading role at the highest technological, scientific and management levels of the Gaia Data Processing & Analysis Consortium (DPAC). Firstly, a significant part of the software system that performs the ingestion, data reduction, production and verification of the Gaia satellite data is being designed, implemented, tested and operated by our groups, using large supercomputing facilities such as CSUC, CNS/BSC and CESGA. Secondly, off-line processes for astrophysical parameters and photometric standardisation are now fully operational and will be adapted to the evolving behaviour of the instrument in terms of stray light, basic angle variations and contamination on the optics. Finally, the tasks around the Gaia archive will become critical in the next years to support the operations for four data releases, with increasing volume and complexity of the data, and the intensive associated scientific exploitation, including the implementation of several sophisticated archive tools. And last but not least, it is time for our own science exploitation of the real data that will be made public in the releases, because this is the primary goal of the participation in Gaia ICCUB members, to address the challenging science cases .
ICCUB members have important responsibilities in the units for simulations (CU2), core processing (CU3) and CU5 (photometry), and manage the Data Processing Center of Barcelona (DPCB). The ICCUB also leads the Gaia Archive unit, funded through an EU FP7 project (GENIUS), and has participated in both an EU FP7 funded initiative (GREAT-ITN) and in a research network (GREAT-RNP) funded by the European Science Foundation to form the next generation of experts in the scientific use of Gaia data. The institute also has one representative in the Gaia Scientific Team and one in the DPACE.
Knowledge gained on data compression related to Gaia has allowed ICCUB to patent a SW/ HW solution and to create a spin-off company, DAPCOM Data Services S.L. DAPCOM is a spin-off company participated by the University of Barcelona (UB) and the Technical University of Catalonia (UPC), specialized on the handling and processing of large amounts of data.
LINES OF RESEARCH
Structure and dynamics of the Galaxy
Dark matter in the Galaxy
Semi-analytical and numerical modelling of galaxy formation and evolution
Data processing of the Gaia mission
Data mining systems for the scientific exploitation Gaia
The intergalactic medium as probed by quasar absortion spectra