The celestial mystery began as a luminous enigma on Earth-bound telescopes before vanishing entirely in Hubble Space Telescope imagery. Now, the elusive apparition has materialized once more as a subtle yet discernible galaxy in the captivating gaze of the James Webb Space Telescope (JWST).
Researchers from the COSMOS-Web collaboration have pinpointed this ethereal entity as AzTECC71, unmasking it as a dusty star-forming galaxy. In simpler terms, it’s a galaxy in the throes of prolific star creation, concealed behind a dusty curtain that challenges visibility, originating nearly 1 billion years post-Big Bang. Previously believed to be exceptionally rare in the early cosmos, the rediscovery of AzTECC71, along with a dozen other potential candidates awaiting detailed exploration in COSMOS-Web data, implies they may be three to 10 times more prevalent than initially anticipated.
Describing the find, Jed McKinney, a postdoctoral researcher at The University of Texas at Austin, exclaimed, “This thing is a real behemoth. Despite its unassuming appearance, it’s birthing hundreds of new stars annually. The sheer excitement lies in the fact that even an entity of such extremes is barely visible in the most refined imaging from our latest telescope. It potentially signifies an entire population of galaxies that has eluded our detection.”
Should this deduction stand scrutiny, it proposes that the early universe was considerably dustier than our prior understanding. The team has documented its revelations in a publication in The Astrophysical Journal.
Led by Caitlin Casey, an associate professor at UT Austin, the COSMOS-Web initiative stands as the premier JWST research endeavor, aspiring to chart the cosmos by mapping around 1 million galaxies in a sky segment equivalent to three full moons. Focused on unraveling the earliest structures of the universe, the project involves a dedicated team of over 50 researchers. Awarded 250 hours of observing time in JWST’s inaugural year, the team received the initial data batch in December 2022, with ongoing influx anticipated through January 2024.
In the cosmic quest, dusty star-forming galaxies present a challenge in optical light visibility due to their light absorption by dust, subsequently re-emitted at longer wavelengths. Termed “Hubble-dark galaxies” before JWST, these elusive entities have eluded comprehensive study. Jed McKinney, a postdoctoral researcher at UT Austin, emphasized the historical bias in understanding galaxy evolution, limited to optical perspectives with Hubble, showcasing less obscured, dust-free galaxies.
The emergence of AzTECC71, initially detected as a vague dust emission blob by the James Clerk Maxwell Telescope in Hawaii, showcases the power of multi-telescope collaboration. Following identification by the COSMOS-Web team using data from the ALMA telescope in Chile, the JWST observations at a wavelength of 4.44 microns revealed the faint galaxy’s existence in the same location. Notably, at shorter wavelengths below 2.7 microns, it remained invisible.
As the team delves into unveiling more of these JWST-faint galaxies, McKinney highlighted the groundbreaking capabilities of JWST. “With JWST, we can, for the first time, study the optical and infrared properties of this heavily dust-obscured, hidden population of galaxies,” he stated. The telescope’s sensitivity enables it not only to peer into the farthest cosmic realms but also to penetrate the densest dusty veils.
The estimated redshift of the observed galaxy is approximately 6, placing it around 900 million years post-Big Bang. The study, featuring authors from UT Austin, includes McKinney, Casey, Olivia Cooper (a National Science Foundation graduate research fellow), Arianna Long (a NASA Hubble fellow), Hollis Akins, and Maximilien Franco. Their collective efforts promise to unveil more secrets of the universe, hidden within the cosmic tapestry.
Source: University of Texas at Austin