James webb deep field

The James Webb Deep Field, released on July 11, 2022, shows thousands of galaxies in a tiny patch of sky, revealing unprecedented details of the early universe.

About this subject

The James Webb Space Telescope (JWST) Deep Field, released on July 11, 2022, is the deepest and sharpest infrared image ever taken. It captures the galaxy cluster SMACS 0723, located about 4.6 billion light-years from Earth. Due to gravitational lensing, the light from even more distant galaxies is magnified and distorted, allowing astronomers to observe objects that existed just 600 million years after the Big Bang.

The image was produced in only 12.5 hours of exposure, a remarkable achievement compared to the weeks required by the Hubble Space Telescope for similar deep fields. Webb uses its 6.5-meter mirror and infrared instruments to penetrate cosmic dust clouds, revealing stars and galaxies invisible in visible light. The photographed region is equivalent to a grain of sand held at arm's length, yet it contains thousands of galaxies of varying ages, sizes, and colors.

Astronomers have already identified hundreds of high-redshift galaxy candidates, some with z > 8, corresponding to less than 700 million years after the Big Bang. These data are helping to understand the formation of the first galaxies, the evolution of supermassive black holes, and the reionization of the universe. The success of Webb's deep field paved the way for the JWST Advanced Deep Extragalactic Survey (JADES), which has already observed hundreds of thousands of galaxies in larger sky areas.

A technical curiosity: the colors of the galaxies in the image are not arbitrarily enhanced. Each Webb infrared filter is mapped to a visible color, allowing astronomers to estimate distances and compositions. The reddest galaxies are the oldest and most distant, while blue ones are closer and rich in star formation. This image marked a milestone in modern astrophysics, surpassing the famous Hubble Ultra Deep Field in sensitivity and resolution.

Frequently Asked Questions

What is the James Webb Deep Field?

It is the first deep-field image from the James Webb Space Telescope, showing galaxy cluster SMACS 0723 with thousands of background galaxies, some over 13 billion light-years away.

How is Webb's deep field different from Hubble's?

Webb observes in infrared, allowing it to see older galaxies obscured by dust. It has much higher resolution and sensitivity, and captured the image in only 12.5 hours compared to weeks for Hubble.

What is gravitational lensing and how does it appear in the image?

Gravitational lensing happens when the gravity of a massive object like SMACS 0723 distorts and magnifies light from objects behind it. In the image, it appears as arcs and stretched shapes of distant galaxies.