Using the Hubble Space Telescope, astronomers led by the Cosmic Dawn Center in Copenhagen have studied a galaxy seen nearly 11 billion years ago. Normally, astronomers observe galaxies thanks to the light emitted by these bright objects from billions of stars. However, there are some galaxies that are more difficult to observe because they require a different view.
Instead of observing the light that this galaxy emits, astronomers used an unusual technique and observed the light that it absorbs. If a galaxy is in the same line of sight as another, more distant light source, the gas and dust in the foreground galaxy can absorb some wavelengths of the background galaxy. Chemical elements in the absorbing galaxy absorb light at specific wavelengths, allowing astronomers to analyze the absorbed light and understand what happened on the way to our field of view.
In this case, astronomers discovered an absorbing galaxy using light from a red quasar, an extremely bright galactic nucleus powered by a supermassive black hole. Although they have not yet identified the light coming from the absorbing galaxy, the absorption patterns revealed suggest that this galaxy is mature and similar to the Milky Way. In addition, it was found that the absorbing galaxy and a nearby bright galaxy are likely gravitationally bound, forming a group similar to the local group in which our galaxy is located.
This discovery shows the importance of using different observation techniques to study galaxies, and astronomers plan to continue studying this region of space to learn more about the absorbing galaxy and its surroundings.
