Looking into space like ‘peeking into house of mirrors’

LONDON - A new study has said that gravitational lensing may be even more necessary than originally thought when looking at distant galaxies.

Gravitational lensing occurs when light from a distant object is distorted by a massive object that is in the foreground.

Astronomers have begun applying this concept in a new way to determine the number of very distant galaxies and to measure dark matter in the universe.

When light from a very distant object passes a galaxy much closer to us, it can detour around the foreground object. According to Einstein’s theory, gravity causes light to bend.

Typically, the light bends around the object in one of two, or four different routes, thus magnifying the light from the more distant galaxy directly behind it.

This natural telescope, called a gravitational lens, provides a larger and brighter — though also distorted — view of the distant galaxy, which according to Rogier Windhorst, a professor at the School of Earth and Space Exploration in Arizona State University’s College of Liberal Arts and Sciences, is like looking through a glass coke bottle at a light on a balcony and noticing how it is distorted as it passes through the bottle.

The study indicates that gravitational lensing is likely to dominate the observed properties of very early galaxies, those that are at most 650-480 million years old.

“We show that gravitational lensing by foreground galaxies will lead to a higher number of galaxies to be counted at redshifts z>8-10. This number may be boosted significantly, by as much as an order of magnitude. If there existed only three galaxies above the detection threshold at redshifts z>10 in the Hubble field-of-view without the presence of lensing, the bias from gravitational lensing may make as many as 10-30 of them visible in the Hubble images,” explained Windhorst.

“In this sense, the very distant universe is like a house of mirrors that you visit at the State Fair-there may be fewer direct lines-of-sight to a very distant object, and their images may reach us more often via a gravitationally-bent path. What you see is not what you’ve got!” he said.

“This work clearly shows that we now need JWST-and its superb infrared resolution, dynamic range, and sensitivity-more than ever to disentangle the First Light forest from the foreground trees. We will also need a next generation of object finding algorithms, since the current software is simply not designed to find these rare background objects behind such dense foregrounds. It’s like finding a few ‘nano-needles’ in the mother-of-all-haystacks.”

The letter is published in Nature on Jan. 13. (ANI)