object

jwst red sources

Mysterious red astronomical objects observed by JWST, often involving gravitational lensing or obscured galaxies.
123 related articles

Description

JWST red sources are a class of astronomical objects that appear strikingly red in infrared observations by the James Webb Space Telescope. They are often extremely distant galaxies whose light has been stretched (redshifted) by the expansion of the universe, or galaxies heavily obscured by dust that absorbs blue light and lets red light through. Some of these sources are also magnified by gravitational lensing, where a massive foreground object bends and amplifies the light from a background galaxy, making them visible despite their faintness.

History

The first JWST deep-field images in 2022 revealed an unexpected population of compact, red sources, nicknamed 'little red dots.' Their nature is still debated, with some being candidate massive galaxies in the early universe and others possibly obscured active galactic nuclei.

How it works

The redness arises from two main mechanisms: cosmological redshift, where the expansion of space stretches light to longer wavelengths, and dust extinction, where small particles preferentially scatter and absorb shorter wavelengths. Gravitational lensing can further distort and brighten these sources, sometimes producing multiple images or arcs. JWST's infrared sensitivity allows it to detect these faint, red objects that were invisible to earlier telescopes like Hubble in visible light.

In practice

Studying these sources helps astronomers understand galaxy formation and evolution in the early universe, and tests models of dark matter distribution through gravitational lensing.

Fun fact

Some JWST red sources are so distant that their light has been traveling for over 13 billion years, meaning we see them as they were when the universe was less than 5% of its current age.

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