He James Webb Space Telescopecapable of diving into the early universe, is showing incredible things, the latest being the merger of two galaxies and their huge black holes when the universe was only 740 million years old.
This detection, the most distant and primitive ever obtained of a merger of two black holes, will help astronomers understand how the origin and evolution of these objects were in the early universe.
The discovery, made by an international team of astronomers, was possible thanks to the cameras of the James Webb, built by the POTthe European Space Agency (ESA, in English) and by the Canadian Space Agency (CSA, in English).
The details were published this Thursday in the magazine Monthly Notices of the Royal Astronomical Society.
The enigma of supermassive black holes
Most massive galaxies – including the Milky Way – have within them a black hole supermassive with a mass millions of times greater than that of the Sun.
It is believed that heSupermassive black holes have had a great impact on the evolution of galaxies where they reside, but scientists still don't fully understand how they became so massive.
Finding gigantic black holes already in the first billion years after the big Bang indicates that this growth must have occurred very quickly and very soon.
Now, new Webb observations have provided evidence of an ongoing merger of two galaxies and their massive black holes. when the Universe was only 740 million years old. The system is known as ZS7.
Massive black holes that actively accumulate matter exhibit distinctive spectrographic characteristics that allow astronomers to identify them. In the case of very distant galaxies, like those in this study, they can only be observed with Webb.
“We find evidence of very dense, fast-moving gas in the vicinity of the black holeas well as hot, highly ionized gas illuminated by the energetic radiation that black holes usually produce in their accretion episodes,” explains lead author Hannah Übler, from the University of Cambridge (United Kingdom).
“Thanks to the unprecedented sharpness of its imaging capabilities, Webb also allowed our team to spatially separate the two black holes.”
The team discovered that one of the two black holes has a mass 50 million times greater than that of the Sun.
“The mass of the other black hole is likely similar, although it is much more difficult to measure because this second black hole is buried in dense gas”, adds Roberto Maiolino, from the University of Cambridge.
“Our findings suggest that fusion is an important pathway through which black holes can grow rapidly, even at the cosmic dawn,” and that “Massive black holes have been shaping the evolution of galaxies since the beginning” of the times, suggests Übler.
“The stellar mass of the system we study is similar to that of our neighbor the Large Magellanic Cloud,” adds Pablo G. Pérez-González, from the Astrobiology Center (CAB), CSIC/INTA.
“We can try to imagine how the evolution of merging galaxies might be affected if each galaxy had a supermassive black hole as big or bigger than the one we have in the Milky Way.”, says the Spanish researcher.
gravitational waves
The study recalls that when the two black holes merge, they will generate gravitational waves that can be detected with the next generation of gravitational wave observatoriessuch as the LISA (Laser Interferometer Space Antenna) mission, recently approved by ESA and which will be the first space observatory dedicated to the study of gravitational waves.
“Webb's results tell us that lighter systems detectable by LISA should be much more frequent than previously assumed,” shared LISA project lead scientist Nora Luetzgendorf of the European Space Agency in the Netherlands.
“It will most likely cause us to tune our models for LISA indices in this mass range. This is just the tip of the iceberg”he added.