Mike Hudson
Professor, Faculty of Science
蓝莓视频 scientists have created the first composite image of the cosmic web of filaments that link galaxies.
The filaments are mostly composed of dark matter, a mysterious substance that doesn鈥檛 shine, absorb or reflect light and comprises about 25 per cent of the universe. Although it can鈥檛 be seen, dark matter has a gravitational pull that affects the path of light, causing the images of distant galaxies to warp.
Mike Hudson, a professor in the Faculty of Science, and Seth Epps, a former 蓝莓视频 master鈥檚 student, created the image using a technique called weak gravitational lensing.
Image of cosmic web confirms researchers鈥� predictions
鈥淔or decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,鈥� says Hudson, a professor in the Department of Physics and Astronomy. 鈥淭his image moves us beyond predictions to something we can see and measure.鈥�
Weak gravitational lensing involves taking a picture of that distorted light, measuring the amount of distortion, and from the those measurements making an image or map of the dark matter that is responsible for them.
Hudson and Epps combined signals from more than 23,000 galaxy pairs, located 4.5 billion light years away, which allowed them to estimate not only the location but also the mass of the filaments they imaged.
Cosmic web has been unobservable until now
Their findings confirm predictions that galaxies across the universe aren鈥檛 isolated like islands in space, but are linked together through a web of enormous filaments that connect the dark matter haloes that surround each galaxy 鈥� a web which has been unobservable until now.
While Hudson and Epps鈥� main goal was to produce an image of these low-density filaments, the team was also aiming to provide a foundation for future studies. Hudson and Epps hope the method they developed to produce the composite image can be used to examine other weak-lensing data sets, with the potential to analyze large data sets from upcoming surveys: for example, space-based data-collection missions such as the European Space Agency鈥檚 Euclid telescope.
Hudson and Epps鈥檚 data came from a multi-year sky survey at the Canada-France-Hawaii Telescope, where another major survey has just begun. Both are being developed to further investigate dark matter鈥檚 role in the universe.
Feature image: The first image of the cosmic web, which is mostly dark matter, that links galaxies. Credit: Mike Hudson and Seth Epps, a former 蓝莓视频 master's student.
