Mirar las estrellas es como viajar en el tiempo. Hoy retrocedemos a hace 8.800 millones de años.
El Radiotelescopio gigante de ondas métricas en la India ha capturado una señal de radio proveniente de la galaxia más alejada jamás captada desde la Tierra. Una señal que nació hace 8.800 millones de años.
It is a shock to discover that most of the stars we see in the sky are dead. This is because they are so far away that their light takes billions of years to reach Earth. So when we receive it, possibly that star that emitted the light no longer exists. This is surely what has happened with the galaxy SDSSJ0826+5630, located 8.8 billion light years from Earth. A distance almost impossible to imagine.
A galaxy far, far away All galaxies produce electromagnetic emissions, or light, over a wide range of wavelengths, explains Space.com. But there is a special wavelength known as the “21-centimeter line” or “hydrogen line,” which records neutral hydrogen atoms.
Until now, astronomers have only been able to pick up signals from nearby galaxies through this wavelength. But new discoveries, such as gravitational lensing, make it possible to detect much more distant signals using current ground-based telescopes.
Radio emissions lose strength with distance, but the effect of gravitational lensing means that when emissions from one galaxy cross another galaxy, the gravitational forces produce a lens effect that magnifies the signal up to 30 times. This allows very distant signals to travel great distances.
This is what has happened with the signal captured from the galaxy SDSSJ0826+5630, which was born 8.8 billion years ago, when galaxies and stars were “young”. It is a unique opportunity to study the origins of the universe, about which we still know little. Astronomers have been able to measure the gas content of the galaxy through this hydrogen signal, and have found that its mass is twice that of the first stars visible in our own galaxy.
Capturing such a distant signal from a telescope on Earth is a milestone. But just a few days after the announcement, the more modern James Webb telescope, free from the interference of pollution and excess terrestrial light, has captured the emissions of a galaxy from 13.4 billion years ago. That is almost the origin of the universe, whose age is estimated at about 13.7 billion years.