A group of galaxies called Stephan’s Quintet, contains a rogue galaxy that is actually much closer to Earth than other galaxies. (Image credit: NASA, ESA and Hubble SM4 ERO Team) Using the Hubble Space Telescope, a team of astronomers used a complex technique to discover an elusive 11 billion-year-old galaxy. Instead of observing the light this realm emits, they observe the light it absorbs. Just as we see a light bulb through the light it emits, astronomers often observe galaxies using the light emitted by their stars. Galaxies emit light waves present across the electromagnetic spectrum, and different telescopes are capable of observing these cosmic objects at different wavelengths of light to form a complete picture. But when a galaxy lies along the same line of sight as another, more distant light source, there is another way to make these galaxy observations. For example, when light passes through a background galaxy to the foreground galaxy, the gas and dust in the foreground galaxy absorbs some wavelengths from the background. And because chemical elements absorb light at specific wavelengths, looking for gaps in the light stream — or spectrum — of a background source can tell astronomers where that light has traveled through what before it reaches our telescope. In other words, light in these “spaces” will be absorbed by a foreground object on its way to our point of view.

One potentially useful source for this technique is quasars, which are extremely bright galactic cores fueled by supermassive black holes that spew jets of radiation and matter while feeding on surrounding matter. around. Related: Astronomers may have discovered the closest black holes to Earth “To find absorbing galaxies, we first look for especially red quasars,” said Johan Fynbo, an astronomer at the Cosmic Dawn Center. “Because stardust tends to absorb blue light, not red, if there is a dusty galaxy in the foreground, the quasar will appear red.” He and his team discovered several absorbing galaxies by analyzing light from red quasars, but when they accomplished that, they faced a much more difficult task: searching for light from red quasars. light emitted from the absorbing galaxy itself. A firefly on a cosmic beacon When located exactly behind a galaxy, quasars tend to block our view of galaxies ahead due to their extreme brightness. So much so that they essentially overwhelm the combined light of all the stars in the entire galaxy. This makes detecting a galaxy absorbing its own light output like trying to spot a firefly perched on a lighthouse while it is standing on land. Although this may be too difficult a challenge for many, Fynbo and his colleagues still enjoy it.

Unfortunately, scientists have yet to determine whether the light came from their recently discovered 11 billion-year-old absorbing galaxy, but the absorption pattern this object revealed is remarkable. This galaxy, seen when our 13.8 billion-year-old universe was only about 3 billion years old, absorbs more light than other galaxies found in a similar way, which means it could be a more mature galaxy like the Milky Way. . “The features we found in the missing light tell us about the dust in the foreground galaxy,” said Lise Christensen, a member of the discovery team and astronomer at the Cosmic Dawn Center. . “In fact, the dust appears to be similar to the dust we see locally in the Milky Way and in one of our neighboring galaxies.”

The team was also able to determine that this galaxy has a bright counterpart. This galaxy, which appears to be birthing stars at an extremely rapid rate, is so close to the absorbing galaxy that the team even thinks the two are likely gravitationally bound together. This means that at some point after being noticed, the two galaxies likely formed a galaxy group similar to the local group where the Milky Way is located. Fynbo plans to revisit this region of space with other instruments, including the La Palma Nordic Optical Telescope, to search for other members of this galaxy group in the hope of seeing the fascinating galaxy. The receptor emits its own light. “This makes studying galaxies even more interesting,” the astronomer concluded. The team’s research has been accepted for publication in the journal Astronomy & Astrophysics. In the meantime, a pre-peer-reviewed version is available on the arXiv research repository.

source: https://arxiv.org/abs/2308.15781