A team of researchers has confirmed this dilemma with data gathered using a new telescope technology that relies on shape-shifting mirrors. According to their study, which was published last month in the Monthly Notices of the Royal Astronomical Society, precise measurements of the rate at which the universe is expanding don’t match the standard model that scientists have been using for decades.
Physicists Geoff Chen and Chris Fassnacht of the University of California, Davis and their colleagues took measurements of three gravitationally-lensed quasars.
These are extremely bright, active and distant galaxies containing supermassive black holes that often emit massive jets of highly accelerated matter.
To study the three systems, they used both the Hubble Space Telescope and the W. M. Keck Observatory’s Adaptive Optics system.
Adaptive Optics systems can compensate for the atmospheric distortion seen with ground-based telescopes.
Astronomers detected massive galaxy
Astronomers detect distant quasars by using massive galaxies located nearer to the Earth as a kind of ‘magnifying glass’. As this galaxy move between us and a quasar, their gravity bends space to give us a better view of the quasar beyond.
This process forms different images of the quasar, however — formed by the bent light taking different routes on their way to Earth.
As the brightness of quasars fluctuates, these images then appear to flicker at different times. From these time delays, physicists can calculate the rate of the universe’s expansion — a property referred to as the Hubble constant.
This is the first time that a ground-based Adaptive Optics system has been used to determine the Hubble constant.
The mystery of the Hubble Constant
The Universe is always getting bigger, stretching galaxies farther apart. For decades, scientists have attempted to measure how fast the Universe is growing – a number called the Hubble Constant.
Researchers piece together the Universe’s history by studying the glow of radiation left over from the Big Bang about 13.8 billion years ago, called the cosmic microwave background (CMB).
When scientists study the CMB, they’re looking both far into the distance and far into the past, since light travels at a constant speed.
History of the Universe
Based on those observations, scientists have found that after the Big Bang, the Universe at first expanded very quickly. Then the expansion slowed as the gravity of dark matter - a mysterious, invisible force that makes up about 85 percent of all matter in the Universe - pulled back.
But recently, they have run into a problem.
Measurements of the contemporary Universe show it’s expanding much faster than the standard model predicts. Riess’ April study found that the Universe is expanding 9 percent faster than predicted by calculations based on the CMB.
New technology confirmed the dilemma – but we’re no closer to solving it
For the new study, the researchers used a cutting-edge mirror system at the Keck Observatory telescope in Hawaii. The device uses flexible mirrors that can correct for distortions caused by Earth’s atmosphere and return extra-sharp images of objects in the sky.
The researchers pointed the telescope toward three systems of bright, highly active galaxies called quasars.
They studied the quasars using a process called gravitational lensing, which measures the way light gets bent as it travels around massive objects on its way toward Earth. A massive object (like a giant galaxy, say) bends light in a variety of directions, which allows scientists to see different, distorted versions of the same quasar from slightly different times in its past.
They can then compare those various images to calculate how long a quasar’s light takes to reach us and gather information about how much the Universe expanded during that travel time.
Like the previous studies, the new results showed that the Universe is expanding more rapidly than the standard model predicts. The researchers compared their results to data from the Hubble Space Telescope, and the findings were consistent.
Fassnacht said he hopes scientists will continue to employ this new telescope technology to gather more precise data as they search for missing pieces in their understanding of the Universe.
“Perhaps this will lead us to a more complete cosmological model of the Universe,” he said.
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