It is believed the formation and growth of most galaxies across the universe have been fueled by supermassive black holes that are growing together with their host galaxy, as they collect matter to get millions of solar masses. Chasing the early stages of extreme objects such as supermassive black holes is among the missions of future powerful telescopes.
A comprehensive estimate has been presented in a study that is led by researchers of the Instituto de Astrofisica e Ciencias do Espaco (IA). The study predicts the number of young galaxies with active supermassive black holes at their cores that should have existed when the universe was said to be less than 7 percent of its current age, and which are within the reach of future X-ray and radio telescopes already in the making.
This study was published in the Monthly Notices of the Royal Astronomical Society, and shown this week at the SPARCS IX meeting, the science and technology of the future Square Kilometer Array (SKA) radio telescope are being discussed.
The results may help the most effective observing plans for SKA and for the ESA's Athena X-ray space observatory. Both observatories will be used to look into the same period in the history of the universe explored by the study.
"Since there is a long wait until Athena and SKA will be available for science, there is time to modify their goals for the best," says Stergios Amarantidis, of IA and Faculdade de Ciências da Universidade de Lisboa (FCUL), the first author of the paper.
"For example, a past Athena white paper mentions a prediction of one order of magnitude fewer supermassive black holes than we found. They will use their result to make a preliminary plan for future surveys. Our results can now be used to improve the strategy and prepare more effective surveys."
They used the eight computational models developed by other teams of scientists and applying their current knowledge about galaxy evolution, the scientists predicted that in an area of the sky the size of the full moon, Athena will be able to spot X-ray activity from 2,500 supermassive black holes at the cores of very young galaxies in the early universe.
The results of this study suggest that radio emissions will be less abundant at the early ages, but telescopes that are powerful such as SKA will be able to identify tens of these sources in the same area of the sky.
"This work puts into evidence the predictive powers of current state-of-the-art models of galaxy formation and will guide us to make better use of the powerful telescopes being built," says José Afonso, of IA and FCUL, and second author of the paper. "At the same time, it also shows where our understanding of the first active galaxies still needs to be improved, something that will require all of our observational efforts during the coming years. The early universe is still largely hard to explain."
