Matter in intergalactic space is organized into a vast network of interconnected filaments, known as the cosmic web. Now, after hundreds of hours of observations, an international team of researchers from Japan has captured the sharpest telescope image ever seen of one of these cosmic filaments across the Universe. This filament joins two actively forming galaxies and dates back to a time when the Universe was only about 2 billion years old. From the Subaru observatory, the study of this cosmic web and its relation to dark matter has been carried out. Read on to learn about this great news from the world of astrophysics.
The Cosmic Web and Dark Matter
Dark matter, which makes up about 85% of all matter in the Universe, takes a crucial role in shaping cosmic structures. Under gravity’s influence, it shapes a vast, intricate web of filaments. At the intersections of these filaments, the brightest galaxies take form. This cosmic web serves as the backbone of the Universe, guiding the flow of gas that fuels star formation in galaxies. Studying how this gas moves and interacts might truly migliorate our understanding of how galaxies form and evolve.
Nevertheless, directly studying this intergalactic gas is extremely hard . Scientists have mainly detected it indirectly — by measuring how it absorbs light from distant, bright objects. These observations, though valuable, do not clearly show how the gas is distributed. Even hydrogen, the most abundant element in the Universe, emits only a very faint glow, making it nearly not possible for previous-generation telescopes to detect this elusive gas.
A Breakthrough with MUSE and the large telescope
In this recent study, an international team led by researchers at the University of Milano-Bicocca and taking onto account scientists at the Max Planck Institute for Astrophysics (MPA) gained an unprecedented high-definition picture of a cosmic filament using MUSE (Multi-Unit Spectroscopic Explorer), an innovative spectrograph installed on the Very Large Telescope at the European Southern Observatory in Chile.
Even with the advanced capabilities of this sophisticated instrument, the research group had to continu onee of the most ambitious MUSE observation campaigns ever done in a single region of the sky, acquiring data over hundreds of hours to detect the filament at high significance.
The Sharpest Image Ever of a Cosmic Filament
The investigation, whose leader is by Davide Tornotti, PhD student at the University of Milano-Bicocca, used this ultrasensitive information to lead on the sharpest image ever obtained of a cosmic filament spanning 3 million light-years and connecting two galaxies, each hosting an active supermassive black hole. The achievement, recently published in Nature Astronomy present new avenues to directly constrain gas properties within intergalactic filaments and to define again our understanding of galaxy formation and evolution.
Tracing the Cosmic Web with Supercomputer Simulations
Davide Tornotti explains that by capturing the faint light emitted by this filament, which traveled for just under 12 billion years to reach Earth, they were able to precisely characterize its shape.
“For the first time, we could trace the boundary between the gas residing in galaxies and the material contained within the cosmic web through direct measurements.”
The investigators took advantage of supercomputer simulations of the Universe run at MPA to calculate predictions of the awaited filamentary emission given the current cosmological model. “
When comparing to the novel high-definition image of the cosmic web, we find substantial agreement between current theory and observations,” Tornotti adds.
What This Means for Our Understanding of the Universe
This discovery and the encouraging agreement with supercomputer simulations are the main point to understanding the tenuous gas environment around galaxies and open up novel possibilities to pin down the galaxies’ fuel supply.
Fabrizio Arrigoni Battaia, MPA staff scientist, who is also part of the study, concludes that they are thrilled by this direct, high-definition observation of a cosmic filament. However, as people say in Bavaria: ‘Eine ist keine’ – one doesn’t count. So they are gathering further data to uncover more such structures, with the last goal to get a undersandable perspective of how gas is distributed and flows in the cosmic web.