Soon after the start of the NASA/ESA/CSA James Webb Space Telescope’s science operations, astronomers noticed something unexpected in the data: red objects that appear small on the sky, located in the distant, young universe. Come to be known as “little red dots” (LRDs), this intriguing class of objects is not well understood at present, sparking new questions and prompting new theories about the processes that occurred in the early universe.
A team of astronomers sifted through James Webb Space Telescope data from multiple surveys to compile one of the largest samples of “little red dots” (LRDs) to date. The team started with the Cosmic Evolution Early Release Science (CEERS) survey before widening their scope to other extragalactic legacy fields, including the JWST Advanced Deep Extragalactic Survey (JADES) and the Next Generation Deep Extragalactic Exploratory Public (NGDEEP) survey.
From their sample, they found that these mysterious red objects that appear small on the sky emerge in large numbers around 600 million years after the big bang and undergo a rapid decline in quantity around 1.5 billion years after the big bang. Spectroscopic data of some of the LRDs in their sample, provided by the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES), suggests that many are accreting black holes. However, further study of these intriguing objects is required.
[Image description: Six Webb images of little red dots are combined in a two-row mosaic. Each little red dot is centered within a square frame and lies against the black background of space. Each dot has a yellow-white circular core surrounded by a red, fuzzy ring. White text in the top left corner of each box lists the source’s name from the Webb surveys, and its redshift. From left to right, the top row reads CEERS 14448, z = 4.75; NGDEEP 4321, z = 8.92; and PRIMER-COS 10539, z = 7.48. The bottom row reads CEERS 20320, z = 5.27; JADES 9186, z = 4.99; and PRIMER-UDS 17818, z = 6.40.]