S-PLUS: The Universe in true colors
S-PLUS (Southern Photometric Local Universe Survey) is an astronomical facility in Chile (Cerro Pachón), dedicated to mapping the observable Universe in 8 narrow-band filters and 5 broad-band (Sloan-like, ugriz) filters in the optical region. The 0.87m mirror of the T80-South telescope, combined with a field of view of 1.5 square degrees and an 85 Mega-pixel camera, will produce high-quality images and a unique spectral resolution for millions of objects over several thousand square degrees. Together with its twin observatory in the northern hemisphere, the T80-North, and its sister survey J-PLUS, these unique instruments will cast the first light on a multi-color Universe, over more than half the extragalactic sky.
This multi-purpose astrophysical survey in the southern hemisphere will start in 2015. During 3-4 years we will observe more than 6,000 square degrees (1/7 of the whole sky), covering the entire visible region of the electromagnetic spectrum (3500 A to 10,000 A).
S-MAPS will discover an unprecedented number of stars, galaxies, supernovas, quasars and solar system objects, which will be mapped with exquisite accuracy, providing a huge legacy of images and data that can be mined by professional astronomers and the general public. It will map the still relatively “virgin” Southern sky, and provide the first three-dimensional map of our local Universe in that region.
New science with S-PLUS
This 3D map of the cosmos, along with the most complete inventory of objects ever collected, will allow a wide variety of science applications: we will be able to see in exquisite detail the web of structures that holds the Universe together, which will help us understand the nature of dark matter and dark energy; we will uncover how galaxies have evolved since the Big Bang; we will map the geography of the Milky way, as well as our solar system neighbourhood; and we will discover hundreds of thousands of quasars, as well as hundreds of supernovas. For more information about the S-PLUS science, click here.
When we look at the sky on a clear night, and we see a bright strip of light across the sky, we are actually looking at the light from billions of stars that make up the Milky Way (see the picture on the right, which was actually taken in Chile, where the center of the galaxy is more easily viewed). The stars of the Milky Way can be so distant, and so small, that we can’t see them individually, so most of them appear to us as blurred smudges. These smudges occupy an elongated stripe in the sky, which means that stars are not evenly distributed, but they concentrate on some regions more than others. This region is our galaxy, the Milky Way, which appears to us as a huge band in the sky because it has the form of a thick disk with a bulge in the middle, and we are looking at this disk from inside it (the Sun is roughly midway from the bulge to the outer limits of the galaxy).
When we look out of the disk of the galaxy, we start to see more clearly objects which are not in the Milky Way, such as other galaxies. And, if we look very carefully and map a large number of these galaxies, we notice that the galaxies themselves are not distributed homogeneously across the Universe: they are more often found close to other galaxies, in groups or clusters of galaxies.
Atoms, stars, galaxies… the Universe!
When we look at vast distances across the Universe, we see hundreds of millions of galaxies. It doesn’t matter how far we look, we always seem to find more galaxies – and, because the speed of light is finite, far away in space means far back in time!
When we look at the distribution of galaxies in the Universe, what we see is a web-like structure, where the fibers of the web are made of hundreds or thousands of galaxies. Gravity is the driving force that pulls galaxies towards each other, creating rich regions with many galaxies, and emptying vast bubbles known as voids, where hardly any galaxy can be found.
But are these galaxies telling us anything? What is their distribution, and why have these galaxies formed in some places rather than others? These are ultimately questions about our own origins. Studying the distribution of galaxies can tell us a lot about how the Universe began, and what it is presently made of.
The role of S-MAPS
The best way to understand how our Universe evolved up to its present state is to map very carefully the types and positions of galaxies, quasars and supernovas in the Universe. We need to observe many millions of galaxies over distances of billions of light-years, in order to beat the statistics and reach a good accuracy in that measurement. We also need to reach deep in the Universe, in order to observe how the Universe went from a decelerated phase (dominated by atoms and dark matter) to the present accelerated phase (dominated by dark energy).
S-PLUS, J-PLUS and J-PAS will be the ultimate instruments to do this massive, precise 3D mapping of the Universe. These instruments will be able to observe hundreds of millions of galaxies, out to distances of more than 3 Gpc (that is, more than 9 billion light-years). At the end of these surveys, we will not only know much better how our Universe began and evolved in time, but we will also have a near-complete map of our observable Universe.
While professional astronomers will be busy exploring the catalogs and statistical properties of this survey, we will also make sure that the general public can travel inside this 3D map of the Universe, visiting places and times that, until recently, we could only dream of.
The international collaboration that is designing, financing and managing the project is a consortium of brazilian and spanish institutions, funding agencies and universities.
S-PLUS, J-PLUS and J-PAS are a part of large collaboration, with more than 100 scientists, engineers and computer scientists. The list of members can be found on the J-PAS website. The Principal Investigators are Claudia Mendes de Oliveira (IAG-USP), Renato Dupke (ON) and Laerte Sodré Jr. (IAG-USP).