Table of Contents
- 1 What is known about Einstein’s zigzag
- 2 What is gravitational lensing
- 3 How J1721+8842 was discovered
- 4 How Einstein’s zigzag can help solve the cosmological crisis
- 5 **How does the alignment of galaxies in the J1721 + 8842 system create the ”Einstein zigzag” effect, and why is this a rare occurrence?**
The James Webb Space Telescope helped scientists discover the first “Einstein zigzag”. This is one cosmic object, a quasar, repeated six times through a gravitational lens. The effect is named because the term “gravitational lensing” was first coined by Albert Einstein in 1915.
Why is this discovery important and who is its author? Channel 24, after examining the material Space.com.
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What is known about Einstein’s zigzag
The system, named J1721 + 8842, consists of a quasar – an extremely bright galactic nucleus – lensed by two galaxies. This is an amazing discovery, an example of the fascinating phenomenon of space-time curvature described in Albert Einstein’s theory of relativity.
Einstein’s first zigzag seen by humanity may help scientists to solve two of the biggest mysteries in cosmology. The first mystery concerns the nature of dark energy, or the force driving the accelerated expansion of the Universe, which makes up about 70% of cosmic energy and matter. The second is related to the difference that scientists find when they measure the expansion rate of the Universe, called the Hubble constant.
I am excited not only because this is an amazing natural phenomenon, but also because this system has incredible promise for measuring cosmological parameters. This lensing system has the ability to set limits on both the Hubble constant and the dark energy equation of state, which was not possible before.
– says Martin Millon, one of the authors of the discovery and a cosmologist at Stanford University.
What is gravitational lensing
According to the general theory of relativity, massive objects cause curvatures in the real fabric of space-time, which is combined into a single entity. The larger the size of an object, the greater the curvature – a kind of “teeth” it creates in space-time. This curvature is what causes gravity: larger objects have a stronger gravitational pull.
How gravitational lensing works / NASA, ESA & L. Calçada
Gravitational lensing occurs when light from a distant object passes through a large object that acts as a lens. It bends, bends around the big body in different directions. As a result, light coming from the same source can reach the telescope from different directions and at different times.
This creates the effect of one object appearing in several places in an image. This is how phenomena such as “Einstein rings”, “Einstein crosses” and, in the case of the quasar J1721 + 8842, “Einstein zigzag” arose.
How J1721+8842 was discovered
This particular quasar was first observed in 2017 by astronomer Cameron Lemon using the Pan-STARRS telescope at the Haleakala Observatory in Hawaii. At first, it was believed that the object was creating only four images.
However, due to the sensitivity of the James Webb Telescope, it was possible to discover that two galaxies were lensing this quasar at the same time, creating six images. In this case, the most distant galaxy is also lensed by the nearest one.
Gravitational lensing created by a single galaxy typically produces two to four images of the source, depending on their alignment. In this case, there is a special alignment of two galaxies and a distant quasar that creates a rare six-image arrangement.
Millon explained.
This arrangement is called “Einstein zigzag” because the path of the two images surrounds the first galaxy on one side and then is destroyed by the second galaxy on the other side, creating a zigzag pattern. This discovery not only shows the amazing beauty of space, but it also helps to study the basic laws of physics, such as the expansion of the Universe and the nature of dark energy.
The study’s lead author, Frédéric Dux, a scientist at the astrophysics laboratory at the École Polytechnique Fédérale de Lausanne, noted that this is the first time scientists have recorded such a perfect alignment of three different materials that together form a gravitational lens.
Usually, there are only two objects in a gravitational lens – for example, a galaxy that acts as a lens, and another galaxy behind it, whose light is bent by the front one. In fact, there are examples of lenses that occur as a result of the interaction of several galaxies at the same time, as occurs in galaxy clusters. But in such cases, there is a negative effect of various factors combined. A single galaxy acting as a perfect lens is extremely rare, as their alignment is usually not precise enough,
Duke explained.
However, the case of J1721+8842 was very special.
The nearest galaxy that forms this lens is located at such a distance that its light took 2.3 billion years to travel to Earth. And the light from a distant galaxy flew to us for 10 billion years.
Despite the great distance between the two galaxies, Dukes says that they form such a perfect alignment that they are both simultaneously drawing light from the source of the quasar, which is around is 11 billion light years away. In addition, the closer galaxy also gives light from the intermediate galaxy.
Quasar J1721+8842 / Observations by Frederic Dux
“This is a very rare phenomenon. We estimate that only one in 50 thousand lensed quasars could have such an arrangement… And because we only know about 300 such quasars, we were very lucky to find this one! It’s quite possible that we won’t find the same one again,” says Dukes.
How Einstein’s zigzag can help solve the cosmological crisis
Frederic Dux shared that his team is already working on updated models of the J1721 + 8842 system to measure the Hubble constant.
Most lens quasars can be used for this, but the fact that this system has two different lenses greatly improves the accuracy of the model and thus reduces the uncertainty in the value of the Hubble constant. This is very important at a time when cosmology is facing a crisis due to the so-called Hubble compression.
– explained the scientist.
The Hubble strain arises because measurements of the Hubble constant in the early universe and extrapolation of its evolution out to 13.8 billion years must match measurements in the local Universe . However, these two meanings are very different.
“Of course, differences can be due to measurement errors. Therefore, before we declare an emergency, we must look for possible errors and improve the procedure,” said Dukes.
This particular zigzag could help to reduce measurement uncertainty and bring closer to Hubble constant values obtained by different methods. Additionally, the J1721+8842 system may help refine the equation of state for the dark energy of the Universe.
This is important because this quantity and the Hubble constant are usually resolved together, creating what is known as degeneracy. This means that the two factors can be changed in different directions as long as they stay within the bounds of the data. But thanks to this system, we may be able to separate these boundaries,
– he noted to the scientist.
According to the scientist, this will be a breakthrough, because the correct determination of these two values at the same time is a task that is usually impossible to implement.. Although work in this direction is already underway, important theoretical preparation and technical infrastructure development are needed to avoid mistakes.
In addition, J1721 + 8842 allows us to study a more distant galaxy, which also acts as both a lens and a light source. Thanks to this, scientists can accurately determine its mass, study the history of star formation and the distribution of matter. “This is the first real opportunity to answer such questions for a galaxy at such a large distance,” Dukes concluded.
Although the James Webb Telescope played a key role in discovering the true nature of J1721 + 8842, it is not the best tool for finding such systems.
“JWST provides very deep views of small areas of the sky at the Vera Rubin Observatory that are best suited for tasks like this. Bye bye”.
**How does the alignment of galaxies in the J1721 + 8842 system create the ”Einstein zigzag” effect, and why is this a rare occurrence?**
## Diving Deep into Einstein’s Zigzag: Discussion Questions
This article reveals a fascinating discovery: a quasar exhibiting a rare “Einstein zigzag” phenomenon due to the alignment of two galaxies acting as gravitational lenses. This discovery has profound implications for understanding the universe.
Here are some open-ended questions to stimulate discussion and explore different perspectives:
**Understanding Gravitational Lensing**
1. **The article mentions that “a single galaxy acting as a perfect lens is extremely rare.” Why is this the case, and what makes the alignment of galaxies in the J1721+8842 system so unique?**
2. **How does the concept of gravitational lensing challenge our traditional understanding of light and gravity? What does it reveal about the nature of space-time?**
3. **Imagine you had to explain gravitational lensing to someone with no scientific background. What analogy or metaphor would you use to make this complex concept relatable?**
**Cosmology and the Hubble Constant**
4. **What is the “Hubble tension,” and why is it causing a crisis in cosmology? How might the J1721+8842 system help resolve this tension?**
5. **The article mentions that the discovery ”could help refine the equation of state for the dark energy of the Universe.” Why is understanding dark energy so crucial to our understanding of the universe’s history and future?**
6. **What are the limitations of using gravitational lens systems to measure the Hubble constant? What other methods are currently being used, and how do they compare?**
**Exploring the Universe through J1721+8842**
7. **Besides clarifying the Hubble constant and dark energy, what other valuable scientific insights can be gained by studying J1721+8842?**
8. **What are the potential implications of being able to study the more distant galaxy within the J1721 + 8842 system? What new questions could it raise about galaxy formation and evolution?**
9. **The article mentions that the Vera Rubin Observatory is better suited for discovering such systems. What are the advantages of ground-based telescopes like Vera Rubin compared to space-based telescopes like James Webb?**
10. **Where do you see this discovery leading? What future observations or experiments could build upon this finding?**
This breakdown encourages discussion on the scientific principles behind the discovery, its cosmological implications, and the potential for future research.
