For the first time, researchers using the James Webb Space Telescope (JWST) have confirmed a phenomenon known as the “Einstein zig-zag.” A rare cosmic event, it occurs when light from one object is duplicated six times due to the warping of space-time caused by two massive galaxies. This discovery could resolve critical issues in cosmology, particularly concerning the mysteries of dark energy and the expansion of the universe.
The Einstein zig-zag: A huge breakthrough in cosmology
This cosmic zig-zag phenomenon, seen in the quasar designated J1721+8842, was initially discovered in 2018 with a quartet of identical bright points. These lights were thought to represent a single quasar replicated through gravitational lensing—a visual effect predicted by Albert Einstein in 1915. Einstein theorized that large objects bend the fabric of space-time, causing light from distant sources to follow different paths.
In a study conducted in 2022, astronomers revealed two additional faint points of light alongside the original quartet, indicating the potential existence of a binary quasar. However, this hypothesis was refuted in an analysis published on November 8, 2023. Instead, the analysis proposed that all six points come from a single quasar, as lensed by two galaxies.
Researchers dubbed the unique configuration as the “Einstein zig-zag,” as light from the quasar appears to zig-zag as it navigates around the lensing galaxies.
The core of the Einstein zig-zag phenomenon lies in the concept of gravitational lensing. According to general relativity, large objects create a curvature in space-time; this can bend the path of light traveling nearby. Resultantly, the light from the same object may reach observers at different times, thus creating multiple images of that object, such as Einstein rings, crosses, and, in this situation, a zig-zag.
The significance of J1721+8842 in studying cosmic phenomena
The discovery of J1721+8842 is substantial. The two galaxies lensing the quasar are separated by enormous distances—one whose light has journeyed to Earth for 2.3 billion years, and the other for 10 billion years. The odds of two galaxies being perfectly aligned to produce this effect are about one in 50,000, which makes J1721+8842 an extraordinary find.
Martin Millon, a cosmologist at Stanford University and a member of the discovery team, has shared his enthusiasm about the findings: “This lens system offers the potential to place stringent constraints on both the Hubble constant and the dark energy equation of state, something that is generally not possible.”
Impacts on cosmological measurements and the Hubble tension crisis
The implications of this discovery for cosmology are profound. The “Hubble tension,” a discrepancy between measurements of the universe’s expansion rate, poses quite a challenge. By utilizing the Einstein zig-zag’s lensing configuration, researchers hope to measure the Hubble constant with greater accuracy, thus resolving this crisis.
“Additionally, this lens can also be used simultaneously to constrain the equation of the state of dark energy of the universe,” notes research lead author Frédéric Dux. “This quantity, and the Hubble constant, are typically degenerate, meaning we can ‘move both knobs’ in different directions and still fit the observational data well.”
Although the JWST has been instrumental in uncovering the nature of this cosmic zig-zag, Dux suggests that future wide-field surveys may prove more effective in discovering additional examples. Partnerships with the likes of the Vera Rubin Observatory are anticipated to yield evidence of more lensed quasars.
As researchers continue their efforts, the discovery of the Einstein zig-zag unravels exciting possibilities in cosmology. This rare phenomenon both enhances our understanding of gravitational lensing and promises to illuminate the mysteries surrounding dark energy. With each new scientific finding, we edge closer to understanding our universe.