Researchers at the University of Waterloo have been able to capture the first composite image of a dark matter bridge that connects galaxies together. The scientists publish their work in a new paper in Monthly Notices of the Royal Astronomical Society.
The composite image, which combines a
number of individual images, confirms predictions that galaxies across
the universe are tied together through a cosmic web connected by dark
matter that has until now remained unobservable.
Dark matter,
a mysterious substance that comprises around 25 per cent of the
universe, doesn’t shine, absorb or reflect light, which has
traditionally made it largely undetectable, except through gravity.
“For decades, researchers have been
predicting the existence of dark-matter filaments between galaxies that
act like a web-like superstructure connecting galaxies together,” said
Mike Hudson, a professor of astronomy at the University of Waterloo.
“This image moves us beyond predictions to something we can see and
measure.”
As part of their research, Hudson and
co-author Seth Epps, a master’s student at the University of Waterloo at
the time, used a technique called weak gravitational lensing,
an effect that causes the images of distant galaxies to warp slightly
under the influence of an unseen mass such as a planet, a black hole, or
in this case, dark matter. The effect was measured in images from a
multi-year sky survey at the Canada-France-Hawaii Telescope.
They combined lensing images from more
than 23,000 galaxy pairs located 4.5 billion light-years away to create
a composite image or map that shows the presence of dark matter between
the two galaxies. Results show the dark matter filament bridge is
strongest between systems less than 40 million light years apart.
“By using this technique, we’re not
only able to see that these dark matter filaments in the universe exist,
we’re able to see the extent to which these filaments connect galaxies
together,” said Epps.
Source: Royal Astronomical Society/News
Media Contact
Prof Mike Hudson
University of Waterloo
Canada
Tel: +1 519-888-4567 x32212 (office) / +1 519-497-7363 (mobile)
mike.hudson@uwaterloo.ca
Science Contacts
Prof Mike Hudson
University of Waterloo
Canada
Tel: +1 519-888-4567 x32212 (office) / +1 519-497-7363 (mobile)
mike.hudson@uwaterloo.ca
Mr Seth Epps
University of Waterloo
Canada
Tel: +1 (613) 619-5078 (mobile)
seth.d.epps@gmail.com
Further information
“The weak-lensing masses of filaments between luminous red galaxies” by Epps & Hudson was published in Monthly Notices of the Royal Astronomical Society (paper available here: https://doi.org/10.1093/mnras/stx517).
Notes for editors
The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.
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