A group of astronomers, led by the University of California, Davis has received new data suggesting that the universe is expanding faster than predicted.
The study comes on the heels of a heated debate about how quickly the universe balloons; measurements so far have been inconsistent.
The new measurement of the Hubble constant or the rate of expansion of the universe involved a different method. They used NASA's Hubble Space Telescope (HST) in combination with the W. M. Keck Observatory's Adaptive Optics (AO) to monitor three gravity-charged systems. This is the first ground-based AO technology used to obtain the Hubble Constant.
"When I first started working on this problem more than 20 years ago, the available equipment limited the amount of useful data that you could get beyond observations," says co-author Chris Fasnacht, a professor of physics at UC Davis. this project is the first time we have used the AO at the Keck Observatory for full analysis. For many years, I feel that the AO observations can contribute a great deal to this effort. "
The team's results were published in the latest online edition of Monthly News of the Royal Astronomy In order to exclude any bias, the team conducted a blind analysis; during processing, they kept the final answer hidden even by themselves, until they were convinced that they had addressed as many sources of information as possible. errors that they can think of. This prevented them from making any adjustments to arrive at the "correct" value, avoiding confirmation bias.
"When we thought we had taken care of all possible problems with analysis, we override the answer with the rule that we should ublikuvame any value to find, even if it's crazy. It's always a tense and exciting moment, "says lead author Jeff Chen, a graduate student in the Department of Physics at Davis University.
Unraveling reveals a value that is consistent with Constant Hubble measurements taken from observations of" local "objects nearby to Earth, such as near Type Ia super-gravity or gravity-charged systems; Chen's team uses the latest objects in its blind analysis.
The team's findings add growing evidence that there is a problem with the standard cosmology model that shows that the universe is expanding it is very fast in its history, then the expansion slows down due to the gravitational pull of the dark matter and now the expansion accelerates again due to the dark energy, a mysterious force.
This model of the history of the expansion of the universe is assembled using traditional measurements of a permanent hub taken from "remote" observations of the cosmic microwave background (CMB) – residual radiation from the Big Bang when the universe began 13.8 billion years
Recently, many groups have started using different iki and to study the different parts of the universe, in order to obtain constant Hubble and found that the value obtained from the "local" to "long" observations, it does not agree.
"That's the cosmology crisis," says Fasnacht. "While the Hubble constant is constant throughout space at some point, it is not constant over time. So when we compare Hubble constants coming from different techniques, we compare the early universe (using long-range observations) against. the late, more modern part of the universe (using local, close observations). "
This suggests that there is either a problem with CMB measurements, which the team believes is unlikely, or the standard cosmology model needs to be altered in some way, using new physics to correct inconsistencies.
Using the Keck Observatory AO System with the Keck II Near Infrared Camera Instrument (NIRC2) of the Keck II Telescope Instrument, Chen and his team obtained local measurements of three well-known quasar systems: PG1115 + 080, HE0435-1223 and RXJ1131-1231. [19659Quasarsareextremelybrightactivegalaxiesoftenwithmassivejetspoweredbyasupermassiveblackholeravenou
Although quasars are often very far away, astronomers are able to detect them through gravitational lensing, a phenomenon that acts as a magnifying glass on When a sufficiently massive galaxy closer to Earth hits the path of light from a very distant quasar, the galaxy can act as a lens; its gravitational field distorts the space itself, bending the background quasar light into multiple images and making it look extremely bright.
Sometimes the brightness of a quasar flickers, and since each image corresponds to a slightly different path length from a quasar to a telescope, the vibrations appear at a slightly different time for each image – they do not all arrive on Earth at the same time.
With HE0435-1223, PG1115 + 080 and RXJ1131-1231, the team carefully measures these time delays that are inversely proportional to the value of the Hubble constant. This allows astronomers to decode light from these distant quasars and to gather information about how much the universe has expanded at the time the light was on its way to Earth.
"One of the most important ingredients when using gravity lenses to measure the Hubble constant is sensitive and high resolution," Chen said. "So far, the best Hubble Constant lens-based measurements, all involved, using HST data. When we dug up, we found two things. First, we had consistent values from previous measurements that were based on HST data, proving that AO data may provide a powerful alternative to HST data in the future. Second, we have found that combining AO and HST data produces a more accurate result. "
Chen and his team, as well as many other groups around the globe are doing more research and observation nal to continue to explore. Now that Chen's team has proven that the Keck Observatory's AO system is as powerful as HST, astronomers can add this methodology to their code of techniques for measuring the Hubble constant.
"We can now try this method with more leased quasar systems to improve the accuracy of our Hubble Constant measurement. Maybe this will lead us to a more complete cosmological model of the universe," Fasnacht says.
Astronomers measure the expansion of the universe, get hints of "new physics" (Update)
Geoff C-F Chen et al. SHARP view of H0LiCOW: H0 of three gravity lenses with time delays with adaptive optical images, Monthly Notices of the Royal Astronomical Society (2019). Doi: 10.1093 / mnras / stz2547
W. M. Keck Observatory
Cosmology Crisis: New data suggests universe is expanding faster than estimated (2019, October 23)
retrieved 23 October 2019
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