Astronomers have made a stunning discovery of an “Einstein cross,” a rare phenomenon that magnifies and splits light from a background galaxy using the gravitational lensing effect predicted by Albert Einstein in 1915. The image captures the light from a quasar, a young galaxy with a supermassive black hole at its core, bending and splaying out into a halo around a foreground elliptical galaxy. This unique arrangement provides valuable insights into the universe and offers a glimpse into distant galaxies and massive objects.
The observed Einstein cross consists of four smudges of blue light haloed around the orange foreground galaxy. The foreground elliptical galaxy, located around 6 billion light-years away from Earth, acts as a gravitational lens, warping and quadrisection a bright beam of light from a background galaxy situated approximately 11 billion light-years from our planet. This phenomenon was first predicted by Einstein’s theory of general relativity, which describes how massive objects warp the fabric of space-time.
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Einstein’s theory revealed that gravity is not a force but rather the curvature and distortion of space-time in the presence of matter and energy. As light travels through highly curved regions of space-time, such as around enormous galaxies, it follows a curved path, bending around the galaxy and forming a halo. The appearance of the halo depends on the strength of the galaxy’s gravity and the perspective of the observer. In this instance, Earth, the lensing galaxy, and the quasar have aligned perfectly to create an Einstein ring, duplicating and arranging the quasar’s light along the ring.
The gravitational lens responsible for the Einstein cross was discovered in 2021 using the Dark Energy Spectroscopic Instrument at the Kitt Peak National Observatory in Arizona. Astronomers conducted further analyses with the Multi-Unit Spectroscopic Explorer at the Very Large Telescope in Chile, confirming that they had indeed found an Einstein cross. These findings were recently accepted for publication in The Astrophysical Journal Letters.
Einstein rings are not only appreciated for their captivating images; they play a crucial role in magnifying light and enhancing details in distant galaxies. Reconstructing the pre-bent forms of light smears around these rings provides valuable insights into the properties and structures of very distant galaxies. Additionally, studying the light warping around Einstein rings allows astronomers to gauge the masses of galaxies and black holes, acting as cosmic scales. Moreover, the lensing effect enables scientists to detect otherwise dark objects such as black holes or wandering exoplanets.
The discovery of the Einstein cross is a significant milestone for astronomers, offering a rare and captivating view of gravitational lensing in action. Through this phenomenon, astronomers can gain deeper insights into distant galaxies, measure the masses of celestial objects, and even uncover hidden celestial bodies. The Einstein cross serves as a testament to the power of Einstein’s theory of general relativity and its enduring impact on our understanding of the universe.
