The Hubble constant, the universe’s rate of expansion, is greater than many scientists thought.
The new findings, detailed in the Monthly Notices of the Royal Astronomical Society, confirm the conclusions of another similar survey — that the cosmos is expanding at an accelerated clip.
Previous attempts to measure the Hubble constant have focused on variable stars and supernovae. The latest efforts, led by astronomer Sherry Suyu, used the Hubble Space Telescope to image the light of distant quasars, extra bright galaxy cores, as it bends around galaxies on its way to Earth.
Researchers focused Hubble on the gravitational lensing of six galaxies. As the light from the distant quasars is warped by the gravity of the intermediate galaxy, it becomes both magnified and fractured. The lensing events allowed Hubble to receive multiple images of each quasar.
Because the galaxies aren’t perfectly round, the quasar light is bent at variety of odd angles, creating delays. Some light waves takes a shorter path, while other light waves travel a longer path. These anomalies are compounded by the quasar’s own variability, causing the quasar images to flicker.
These flickers can be used to calculate the Hubble constant.
“Our method is the most simple and direct way to measure the Hubble constant as it only uses geometry and General Relativity, no other assumptions,” Frederic Courbin, an astronomer at the Swiss Federal Institute of Technology in Lausanne, said in a news release.
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