An international research team, of which Carlos Martins, FCT researcher at the Center for Astrophysics of the University of Porto (CAUP), is a member, sought variations in one of the fundamental constants of the universe - the fine structure constant - whose value is used to characterize the behavior of the electromagnetic force.
It has used the world's three most powerful telescopes(VLT, Keck and Subaru) to search for relative velocity variations in the light absorption signature of a Quasar, an extremely bright core of an active, distant galaxy that surrounds a supermassive black hole at its center.
The light from the Quasar HS 1549+1919, located 11.5 billion light-years away, passed through three different galaxies, respectively 10, 9, and 8 billion years ago. Each absorbed part of the Quasar's spectrum, leaving in this absorption clues to how the electromagnetic force behaved at each of these times, which allowed the fine structure constant α (or Alpha) to be measured.
Previous studies suggested that if there were variations of Alpha, they would be very small. By comparing measurements from the three telescopes, it was possible to minimize measurement errors. The data obtained point to the same answer: if there has been any variation of Alpha, and therefore of the electromagnetic force, over the last 10 billion years, it would have been a variation of less than a few parts per million. Michael Murphy, one of the co-authors of the study thinks "that this is the most accurate measurement of its kind to date".
By trying to unveil the true nature of Dark Energy, presenting new and more accurate measurements of the Alpha fine structure constant, this article accepted for publication in the Monthly Notices of the Royal Astronomical Society also contributes to the objectives of the project The Dark Side of the Universe, funded by FCT and coordinated by Carlos Martins. The researcher considers that "to carry out these tests, it is necessary to take the current spectrographs to the limit, and improving them is fundamental for modern cosmology."