Hubble, Gaia produce the most accurate measure of the rate of expansion of the universe

July 12 (UPI) – Combining the observations of the two most powerful space telescopes into orbit, scientists have reached the most accurate measurement of the Hubble constant, the rate of expansion of the # 39; universe.

confirms the tension between the explosion rate in the early and late Universe, researchers report.

Astronomers can measure the expansion of the universe by measuring the redshift of a galaxy, a change in the wavelength of light due to a change in speed. object. By measuring the redshift of galaxies using the Hubble telescope, scientists have established the Hubble constant.

But research on the cosmic microwave background, the oldest radiation of the universe, can also be used to predict the rate of expansion. The hyperbole signature maps of the Big Bang, as measured by the Planck Observatory, suggest a different rate of expansion than the Hubble constant.

Up to now, some scientists suggest that the tensions between the two measurements could be the result of an error or inaccuracy. "With the addition of these new data from the Gaia and Hubble Space Telescope, we now have a serious voltage with Cosmic Microwave Background data," George Efstathiou, a researcher at the Kavli Institute of Cosmology.

Efstathiou helped Planck's investigation of the ancient universe, but did not participate in the latest research involving Hubble and Gaia.

"The tension seems to have become a total incompatibility between us," said Adam Riess, astrophysicist at the Space Telescope Science Institute and at Johns Hopkins University. "At this point, it is clear that this is not simply a rough mistake in a measurement. "

To calculate the Hubble constant, scientists must accurately measure the distance between two galaxies.The redshift of the galaxy can then be compared to its distance to Earth, revealing its remoteness Over time, scientists can characterize the expansion of the universe.

The latest measurements from Gaia and Hubble have allowed scientists to obtain extremely accurate distance measurements. Scientists measure the distance of galaxies using pulsating stars called cepheid variables.The pulses of cepheids are dictated by their intrinsic luminosity. comparing the intrinsic brightness of the star to its apparent brightness measured by telescopes, scientists can calculate their distance from the Earth.

Hubble and Gaia data have helped astronomers calibrate Cepheid distances inside and outside the Milky Way. The stellar markers helped the researchers to obtain the most accurate Hubble constant measurement to date.

Scientists have detailed their new measure this week in the Astrophysical Journal