A new Einstein cross is found

The study, which has collect images from Hubble Space Telescope with spectroscopic lens, a phenomenon predicted by Albert Einstein's theory of General Relativity.In this case, the observed effect is due to the alteration caused by a galaxy that acts like a magnifying glass amplifying and distorting, in four separate images in the form of a cross, the light of another galaxy located 20,000 million light years away.

One of the most striking conclusions of Albert Einstein’s theory of general relativity is that the trajectory of light curves in the presence of matter. And now A new Einstein cross is found.

This effect can be observed in the case of light emitted by a distant galaxy, when its light passes close to another galaxy on its way to the observer.

 The phenomenon is known as gravitational lensing, because it is comparable to the deviation of light rays by the classic glass lenses.

 Similarly, gravitational lenses act like magnifying glasses that change the size, shape, and intensity of the image of the distant object.

One of the most noticeable conclusions of Albert Einstein’s theory of general relativity is that the path of light curves in the presence of the matter. 

This effect can be observed in the case of light emitted by a distant galaxy, when light passes close to another galaxy on its way to the observer.

 The phenomenon is known as gravitational lensing, because it is comparable to the deviation of light rays by the classic glass lenses. Similarly, gravitational lenses act like magnifying glasses that change the size, shape, and intensity of the image of the distant object.

Depending on the degree of alignment of the two sources, multiple images of the distant source can be observed, such as four separate images in the form of a cross (hence the name “Einstein’s cross”), rings, or arcs. 

It is in general extremely difficult to spot a gravitational lens, because the separation between the images produced by the lens is usually very small, requiring high-resolution images to see them. 

It was precisely analyzing Hubble Space Telescope high-resolution images that it was possible to locate an asterism that looked like a new example of Einstein cross.

However, spotting four points of light in the shape of a cross positioned around a galaxy does not assure us that it is a lens, so we must show that the 4 images belong to the same object.

 To do this spectroscopic observations are needed. 

For this reason, a team of Italian scientists led by Daniela Bettoni of the Padova Observatory and Riccardo Scarpa of the IAC, decided to observe spectroscopically with GTC the supposed lens. 

According to Scarpa, 

The result could not have been better. The atmosphere was very clean and with minimum turbulence (seeing), which allowed us to clearly separate the emission of three of the four images. 

The spectrum immediately gave us the answer we were looking for, the same emission line due to ionized hydrogen appeared in all three spectra at the same wavelength. There could be no doubt that it was actually the same source of light“.

A new Einstein cross is found, named J2211-0350 according to its coordinates on the sky. 

The object acting as a lens turns out to be an elliptical galaxy located at a distance of approximately 7 billion light years (z = 0.556), while the source is at least 20 billion light years away (z = 3.03).

 “Normally the source is a quasar, it was with great surprise that we realized the source in this case was another galaxy, in fact a galaxy with very intense emission lines which indicates it is a young object still forming large amounts of stars“, explain Bettoni. 

Quite an achievement for GTC, considering only another lens of this type was known.

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