Over the course of a decade, through observations from the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) project, hundreds of millions of galaxies and stars will be mapped.

October 20th, Text: USP Journal* Art: Gabriela Varão**

The JST250 Telescope at the Javalambre Astrophysical Observatory – Photo: J-PAS

The largest three-dimensional map of the Universe, featuring hundreds of millions of celestial bodies, is beginning to be produced through observations from the J-PAS project (Javalambre Physics of the Accelerating Universe Astrophysical Survey). This survey of galaxies, resulting from a collaboration between Spain and Brazil, will take place at the Javalambre Astrophysical Observatory (OAJ), near the city of Teruel, Spain, with an expected duration of a decade. The J-PAS will observe a vast expanse of the sky, mapping galaxies, stars, and quasars, with the aim of advancing our understanding of dark energy through the formation of large cosmic structures. The project is led by the Centro de Estudios de Fisica del Cosmos de Aragón (CEFCA) in Teruel, in conjunction with USP, the National Observatory (ON) in Rio de Janeiro, and the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain, as part of an international collaboration involving more than 250 researchers from 18 countries.

“The start of observations and the acquisition of the first data from the J-PAS collaboration crown a joint effort by Brazilian and Spanish scientists in the construction of what will be the largest three-dimensional map of the sky,” highlights ON Director Jailson Alcaniz, a researcher at the J-PAS Data Center in Brazil. According to the scientist, the analysis of J-PAS data will require developments in high-performance computing and will significantly deepen our understanding of the universe around us. “Certainly, they will contribute to the formation of the new generation of astronomers in various parts of the world,” he notes.

Astrophysicist Eduardo Cypriano, a professor at the Institute of Astronomy, Geophysics, and Atmospheric Sciences (IAG) at USP, emphasizes the role of J-PAS, especially for Brazilian science. “The participation of Brazilian researchers, from the initial phases of the project to now, when the first data is being distributed, has meant a process of maturation and understanding of the data that does not occur when we enter a project in which we are not protagonists,” he points out.

Sky’s Wide View

Observations from J-PAS are carried out through the JST250 telescope, with a 2.5-meter diameter mirror and a ‘wide-angle’ view of the sky. This telescope is equipped with the JPCam panoramic camera, boasting 1.2 million pixels, currently the second-largest astronomical camera in the world. It utilizes a unique and innovative system with 56 optical filters specially designed for the project, enabling multi-colored images of large areas of the sky, providing detailed information on all objects in its extensive field of view. All of this makes the JPCam-JST250 instrument capable of mapping the Universe and measuring extragalactic distances with the precision needed to trace the Universe in detail.

The initial work of J-PAS is commencing now after a rigorous process of verification, checks, and optimizations of the JST250 and JPCam systems, carried out by scientists, technicians, and engineers from CEFCA. The final phase of commissioning (verification and testing) began in May 2023 and was recently successfully completed after confirming that the JPCam-JST250 system meets all initially planned technical and scientific requirements, with excellent image quality observed across the entire field of view. “JPCam is a prototype, in the sense that there is no other camera like it in the world. The 14 large-format detectors were specifically developed for this project, as well as the complex control electronics and the J-PAS filter system,” describes Antonio Marín, OAJ subdirector and head of the JPCam project. “Due to its extremely high technological complexity, the characterization, validation, and activation of JPCam were challenges that required new engineering developments during the commissioning process.

Up to now, the first 15 square degrees (a unit of measurement of the sky adopted by astronomers) of the map have been observed with all 56 filters of J-PAS, equivalent to the area of 60 full moons. Despite being just the beginning, these data already provide information about a million stars and galaxies, most of which have never been observed with this level of detail before. “JPCam, together with the largest low-width filter system in existence, is a unique specimen in the world, providing a spectrum of each point in the camera of any object, be it a galaxy at the beginning of the Universe or an asteroid near Earth,” explains Renato Dupke, ON researcher and scientific director of the J-PAS project. “This not only gives the project the ability to conduct cutting-edge cosmological studies but also a legacy that enables cutting-edge studies in basically all areas of astronomy.”

Due to its wide field of view, each JPCam image occupies approximately 1 GB of data, and hundreds of images can be taken in a single night. The large volume of data generated by J-PAS requires a dedicated data processing center for storage, management, and processing of the survey data. According to Dr. Héctor Vázquez, head of the Data Processing and Archives Department at CEFCA, “the start of J-PAS data collection is a very special moment as we apply our knowledge and multidisciplinary experience from previous mappings to ensure both the efficiency of astronomical observations and the proper processing of the giant quantity of images they generate.”

A Unique View of the Universe

J-PAS is a project that will leave a legacy for the international scientific community through a unique view of the Universe. Whether through new information or the quantity of this data, covering hundreds of millions of observed objects, J-PAS opens up new research opportunities in almost every field of astrophysics and cosmology.

This idea is reinforced by Professor Laerte Sodré Junior from IAG. “J-PAS illustrates well the time between the conception of a scientific project and its initiation. We began thinking about what would become J-PAS in 2009, and only 14 years later, it begins to produce the data we want to obtain. It was the incessant work of scientists and engineers, in Brazil and Spain, throughout this period that made this possible,” he evaluates. “Now, the data collected by the telescope will help us satisfy our scientific curiosity, helping to answer countless questions about the cosmos. And indeed, they will continue to do so for a long time, representing a legacy for future generations,” he adds.

“The history of astronomy teaches us that the large astronomical maps made in the past marked a before and after in our knowledge of the cosmos,” recalls Carlos López San Juan, scientific subdirector of CEFCA. “J-PAS will be the largest and most accurate multicolor photometric map with the ability to provide spectral information [of radiation and light emissions] from any region of the Universe. As such, it aspires to become a reference for 21st-century astronomy.”

Image comparing preliminary data from J-PAS with available spectroscopic data. The background image is a small region from one of the J-PAS exposures. The graphs present data obtained with J-PAS in each of the 56 filters (in color) in relation to available spectra (in gray) from various galaxies, two stars, and one quasar – Photo: CEFCA via IFUSP.

The prospects for Brazil in the context of collaboration are very encouraging, according to Professor Raul Abramo from the Institute of Physics (IF) at USP. “J-PAS is allowing the participation and leadership of Brazilian scientists in one of the largest and most innovative maps of the Universe today. From now on, we will have numerous opportunities for new discoveries and applications of this data, whether by senior researchers, graduate students, or even undergraduate students,” he notes. “In this way, J-PAS is leveraging the development of a generation of astronomers and physicists working at the forefront of knowledge about dark energy and the origin of galaxies and cosmic structures.” Brazilian participation in the J-PAS project is supported by the Ministry of Science, Technology, and Innovation (MCTI), the São Paulo Research Foundation (Fapesp), the Financier of Studies and Projects (Finep), and the Rio de Janeiro State Research Foundation (Faperj).

For more information: email raulabramo@usp.br, with Professor Raul Abramo

*Communication Office of the Institute of Physics (IF) at USP, with editing by Júlio Bernardes

**Intern under the supervision of Moisés Dorado