Discover ‘Einstein Zigzag’… Can we solve a cosmological mystery? [우주를 보다]

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The James Webb Space Telescope (JWST) found the first image of one quasar as six. The research team named this ‘Einstein Zigzag’. Provided by the Frederick Dux research team

The ‘Einstein Zigzag’ was captured by the James Webb Space Telescope (JWST), the largest existing space telescope. Here is an image showing six quasars (galactic nuclei) in one image, and this arrangement is the result of the ‘gravitational lensing’ effect first proposed by Albert Einstein in 1915. Scientists believe that the this found the greatest unsolved problem in cosmology.

Recorded as J1721+8842, the system consists of two galaxies with very bright quasars, widely separated but aligned. This example shows how curved spacetime is predicted by Einstein’s theory of gravity, general relativity, and J1721 + 8842 ZigZag has a power that normal gravitational lensing does not.

This Einstein zigzag is related to the nature of dark energy and the Hubble-Lemert constant (Hubble constant), which is considered the greatest mystery in cosmology.

Dark energy and the Hubble-Lemert constant are key elements in explaining the expanding universe. Dark energy is believed to drive expansion, accounting for nearly 70% of the total amount of energy and matter in the universe, but its identity is not clear. The Hubble constant is also a velocity law that can measure the expansion rate of the universe.

“This system is not only an amazing natural phenomenon, but also useful for measuring cosmological parameters,” said Martin Milone, a space researcher at Stanford University in the state.” he said

How the curvature of space-time creates a gravitational lens. Provided by NASA, ESA & L. Calçada

Circles, crosses, and zigzags created by gravitational lenses
The theory of general relativity states that objects with mass cause curvature (bending) in the structure of space and time itself, called ‘space-time’. in one four-dimensional continuum. Explain that it is integrated. The larger the size of an object, the greater the curvature that occurs in space and time. Gravity arises from this bending, so the larger the object, the greater the effect of gravity.

Gravitational lensing occurs when light from a background light source passes through a large lens object on its way to Earth and is bent according to its curvature. As they take different paths around the gravitational lens, they approach the mass of the lens at different speeds and are left with different sizes. This means that this light from the same background light source will reach the same telescope at different times.

Therefore, one background illumination can appear in several places in one image, and these objects can create arrays such as Einstein rings, Einstein crosses, or, as in this case, Einstein zigzags.

Of course, JWST is not the first telescope to discover this phenomenon. Lensed quasars, composed of luminous gas and dust surrounding a supermassive black hole, were captured in 2017 by Cameron Lemon using the Panoramic Survey Telescope and the Pan-STARRS telescope system at the Haliakala Observatory in Hawaii.

Typically, gravitational lensing produced by a single galaxy creates two to four images, depending on their alignment. The quasar was lensed four times, but due to its sensitivity, JWST produced six rare images of two distant quasars, which the research team named ‘Einstein Zigzag’.

“In two of the images, the optical path went through one galaxy and was bent by the other, creating a zigzag pattern,” explained Milon.

J1721+8842, observed as part of the Pan-STARRS project in 2017, appears to consist of four examples of lensed quasars. Presented by Pan-STARRS

Frederick Dux, lead researcher and scientist at EPFL’s Institute of Astrophysics, said it was the first time scientists had found such a perfect alignment between three different celestial bodies, creating a gravitational lens. .

Generally, gravitational lensing involves only two things. For example, a galaxy acts as a lens and another galaxy acts as a light source. No single galaxy acts as a perfect lens by itself. This is because the alignment is not sufficient.

In the case of the galaxy that created J1721 + 8842, one galaxy is so far away that light would travel 2.3 billion years to Earth, and the most distant galaxy would travel 10 billion years. Nevertheless, the two galaxies are in almost perfect alignment, playing a role in detecting light from a quasar light source about 11 billion light-years away, and the foreground galaxy a ‘process the light from the central galaxy with a lens, creating ‘Einstein. zigzag’.

“This is rare,” said Dux. “One in 50,000 lensed quasars are expected to have this configuration, and we are very fortunate to have made this discovery when only 300 lensed quasars are known.”

Einstein’s discovery of the zigzag will solve the mystery of cosmology

The research team explained that they are already working on an updated model of J1721 + 8842 to measure the Hubble constant.

Most lensed quasars can be used for this purpose, but since this quasar has two separate lenses, it will constrain the lensing model much better and further reduce uncertainty. in the Hubble constant, the researchers believe. “This is very exciting at a time when cosmology is in crisis due to what we call the Hubble pressure,” said Dux.

The Hubble tension says that if we measure the Hubble constant in the very early universe and extrapolate the evolution of this value over 13.8 billion years of cosmological history (using the models cosmological best), we can estimate the current age of the Hubble constant using When the values ​​should be the same, there is a big difference between the two results.

“Either way, there may be measurement errors, so we must continue to look for possible errors and improve measurements before declaring a definite emergency,” explained the research team.

Image of J1721+8842 with six background quasar appearances (AF). Provided by the Frederick Dux research team

This lens could also be used at the same time to constrain the equation of state of dark energy in the universe. “This is very interesting, because this size and the Hubble constant are usually decreasing, giving good access to the observational data even if you move the two lumps in different directions,” said the team. “Using this system, we can break this recession.”

You can use J1721 + 8842 to test both values ​​at the same time, which is generally not possible. A lot of theoretical work and technical infrastructure development is needed before the two values ​​that the research team wants to study can be measured in a ‘safe’ way to avoid biases and errors.

JWST was crucial in discovering the true nature of J1721 + 8842 as Einstein’s zigzag, but it may not be the best tool for finding more of these elusive configurations.

“Surveys of the Gaia sky, such as Panstars and Euclid or the future Vera Rubin Observatory (LSST), are suitable tools for this study,” said the research team, “We will continue to look for lensed quasars! Yes We expect to find more with LSST and the Euclid mission. “It depends on luck whether you stumble on another zigzag,” he said.

YesThe team’s research has been posted on the pre-publication site ‘ArXiv’.

Gwangsik Lee, Science Column joand999@naver.com

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