The Committee of the ESA Scientific Program (European Space Agency) has just decided that the scientific subject that will address its next great space mission, whose launch is expected in 2028, will be "The hot and energetic Universe". The topic was proposed by a large international team, whose coordinators include Xavier Barcons, from the Institute of Physics in Cantabria (Joint CSIC and the UC Center).
Once the selections has been made, the same team is already working to elaborate a concept of space mission which is capable of addressing the most burning issues in Astrophysics within this subject. The advanced telescope for high Astrophysics (Athena, in English) will provide angular resolution, collection area, spectral resolution, sensitivity and a tracking ability, necessary to revolutionize our view of the hot and energetic universe.
How was ordinary matter grouped to form the large-scale structures that we see in the current Universe? How have giant black holes grown throughout cosmic history and shaped the Universe? These are some of the most important questions in modern astronomy that the next great ESA scientific mission will answer.
Barcons has stated that "after almost 15 years of scientific work and cooperation around this idea, it is very comforting to see that ESA has decided that this is the object of its next scientific mission". The collaboration of Athena, which presented a White Book proposing this scientific subject," is composed of an impressive group of more than 200 scientists, supported by another 1,000 researchers. Now we must continue working to define in detail what the Astronomical Observatory of x-rays, which we need to understand the hot and energetic Universe, should be like".
In spite of the fact that at first sight the sky appears to be populated by stars, the majority of ordinary matter is to be found as tenuous gas at much higher temperatures, invisible to the most powerful optical telescopes. In some places, this hot gas accumulates, forming the greatest coherent structures in the Universe: galaxy clusters. At a temperature of millions of degrees, which it is found at, this gas emits radiation exclusively in the x-ray band.
The key to understanding the formation and evolution of the large cosmic structures is to build a large observatory that is capable of ultrasensitive imaging in x-rays, as well as analyzing them spectroscopically. With this information at hand, a complete tomography can be carried out of those large deposits of hot gas which exist within the remote Universe and which are galaxy clusters, showing gas flows, the turbulence generated and also when and where heavier chemical elements are created.
With a telescope such as Athena, the Universe could also be scrutinized in its "infancy", in search of the first supermassive black holes, millions of times more massive than the Sun, to then see them grow. The matter that feeds the black holes becomes incandescent before being engulfed forever, and emits x-rays abundantly. It is believed that the huge amount of energy released during the growth of the supermassive black holes which the galaxies possess in their Center has been responsible for regulating and interrupting the formation of stars in the Galaxy. "With an x-ray telescope such as Athena we will be able to carry out a complete census of supermassive black holes growing and reliably determine the energy they deposit in the environment", explains Francisco Carrera from the Institute of Physics in Cantabria, who has led a detailed study on this subject within the Athena Consortium.
But an observatory such as Athena will lead to a real revolution in all the corners of Astrophysics Research: from solar wind, to the origin of the enigmatic cosmic bursts of gamma rays, passing through supernovas and the debris they leave in the interstellar environment, or binary stars in accretion. "The winds that are generated around black holes or neutron stars are the testimony of the devastating effects that their gigantic gravitational field produces in their companion stars; with Athena we will be able to study in detail the physical conditions that occur in these extreme environments" says José Miguel Torrejón from the University of Alicante, also a participant in the proposal.
In Spain there is huge scientific interest in this subject, spread by Universities and research centres, particularly in the CSIC. In addition, a consortium of CSIC centres (IMM, ICMA, ICMAB and IFCA) is developing cryogenic calorimeters based on superconductors, such as x-ray detectors, which are essential for an observatory such as Athena. ESA’s decision is expected to attract interest in a multitude of technological aspects around this mission.
En el horizonte de 2028, Europa contará con una impresionante batería de observatorios astronómicos, tanto en tierra como en el espacio, que barrerá todo el espectro electromagnético, entre otros ALMA en ondas milimétricas y sub-milimétricas, la misión espacial JWST (NASA/ESA) en el infrarrojo cercano y el telescopio extremadamente grande (E-ELT) de ESO en el óptico e infrarrojo. Con la decisión adoptada por la ESA, la familia se completará con un gran observatorio de rayos X en 2028, abriendo una oportunidad sin precedentes para estudiar el Universo en todas sus facetas.
On the horizon of 2028, Europe will feature an impressive battery of astronomical observatories, both on land and in space, which will sweep across the electromagnetic spectrum, among others ALMA in millimeter and sub-millimeter waves, the JWST space mission (NASA / ESA) in the near infrared and the extremely large telescope (E-ELT) from ESO in the optical and infrared. With the decision adopted by ESA, the family will be made complete with a large x-ray observatory in 2028, opening an unprecedented opportunity to study the Universe in all its facets.