Water is crucial for life, but for astrophysicists, it holds a deeper significance. Scientists examine water in galaxies, specifically its distribution and its changes from ice to vapor, as important indicators of areas with increased energy, where black holes and stars are formed. In essence, where there is water vapor, something significant is happening.
A recent study conducted by SISSA has unveiled the distribution of water within the J1135 galaxy, located 12 billion light years away. This galaxy was formed when the Universe was in its “teenager” phase, 1.8 billion years after the Big Bang. This water map, possessing an unprecedented resolution, is the first of its kind for such a remote galaxy and serves as the main focus of a study published in “The Astrophysical Journal.” The researchers behind this study explain that the map can enhance our understanding of the physical processes occurring within J1135 and shed light on the dynamics surrounding the formation of stars, black holes, and galaxies, which are still partially unclear.
Examining galaxies: the importance of water
“Water exists not only on Earth but also in different states throughout space. For example, in the form of ice, water can be found in molecular clouds, dense regions of dust and gas where stars are born,” explains Francesca Perrotta, the lead author of the study conducted by the Galaxy Observational and Theoretical Astrophysics (GOThA) team at SISSA. “Water acts as a coating on the surface of interstellar dust grains, which serve as the basic building blocks of these molecular clouds and the primary catalysts for molecule formation in space.” Dr. Perrotta continues, “Occasionally, the tranquility and coldness of these molecular clouds are disrupted by the birth of a star, which releases heat, or a black hole that begins to accumulate matter and emit energy. The radiation from stars and other sources can heat up the icy water, causing it to transition into a gaseous state. As the water vapor cools down, it emits light in the infrared part of the spectrum. Astrophysicists can then observe this emission from water vapor to map the regions in the galaxy where energy is being produced, providing us with unprecedented insights into the formation of galaxies.” This information can also be combined with mappings of other molecules, such as carbon monoxide (CO), which are also utilized in the study of these phenomena.
Gravitational lensing: studying J1135
How is it possible to study a galaxy that exists in such a young and distant Universe? The answer lies in gravitational lensing, a technique that allows for the observation of remote celestial objects through the use of massive spatial objects that are closer to Earth. In accordance with the principles of general relativity, these foreground objects distort the light coming from sources positioned behind them but perfectly aligned with them, functioning like a colossal cosmic lens that enables us to locate and study even the most distant galaxies. Lensing played a crucial role in another recent study conducted by SISSA, which focused on the discovery of J1135.
The formation of galaxies: an ongoing quest for discovery
Dr. Perrotta explains that this study is valuable because it further expands our knowledge in a significant area: “The formation of galaxies is not yet fully understood. There are at least two possible scenarios, which are not necessarily mutually exclusive: one suggests that small galaxies merge to form larger ones, while the other proposes that stars are formed in situ. Studies like ours help us comprehend the processes occurring in that specific galaxy and potentially extract more generalized information from it.” Future observations, similar to those performed by the James Webb Space Telescope, the largest telescope ever sent into space, could unravel further details about J1135 and lead to a more precise mapping of its molecules.