James Webb Space Telescope Discovers One of the Oldest Galaxies in the Universe
The James Webb Space Telescope (JWST) continues to make groundbreaking discoveries since its launch in December 2021. The latest find is one of the oldest galaxies ever spotted in the universe, formed just 390 million years after the Big Bang. Named Maisie’s galaxy after the daughter of the astronomer who first observed it on her birthday, this discovery sheds light on the early stages of the universe. While Maisie’s galaxy is one of the four earliest confirmed galaxies, scientists are also evaluating around 10 others that may be from an even earlier era.
Determining the Age of a Galaxy
Estimating the age of a galaxy is a complex process that involves calculating the redshift, which measures the shift in color due to the galaxy’s motion away from Earth. In an expanding universe, a higher redshift indicates an older object. Initially, the age of Maisie’s galaxy was estimated based on photometry, which measures the brightness of light in images using wide frequency filters. However, to obtain a more accurate estimate, researchers used JWST’s spectroscopic instrument, NIRSpec (Near InfraRed Spectrograph), which splits an object’s light into narrow frequencies to analyze its chemical composition, heat output, brightness, and motion. Based on spectroscopic analysis, Maisie’s galaxy has a redshift of z=11.4.
Unexpected Discoveries and Challenges
During their research, scientists also studied another galaxy called CEERS-93316, which was initially thought to have formed just 250 million years after the Big Bang. However, further analysis revealed a more modest redshift of z=4.9, indicating that the galaxy formed approximately one billion years after the universe’s creation. The initial miscalculation occurred because the galaxy emitted an unusually high amount of light in specific frequency bands associated with oxygen and hydrogen, making it appear bluer than it actually was. This quirk of the photometric method is unique to objects with redshifts of about 4.9.
Implications of the Findings
Maisie’s galaxy not only appeared unnaturally blue but was also much brighter than current models predict for galaxies formed in the early universe. This finding challenges previous assumptions about the formation of massive galaxies in the early stages of the universe. According to Steven Finkelstein, the lead researcher from the University of Texas at Austin, this outcome was likely because of the extreme nature of the galaxy’s brightness and its high redshift. Understanding the formation of galaxies during the early universe provides valuable insights into the evolution of our cosmic environment.
The James Webb Space Telescope
The JWST, with a cost of $10 billion (£7.4 billion), was launched with the goal of peering back in time 13.5 billion years to a point just 100-200 million years after the Big Bang. Equipped with advanced instruments like NIRCam, NIRSpec, MIRI, and FGS/NIRISS, the telescope enables scientists to observe and analyze distant celestial objects in unprecedented detail. The discovery of Maisie’s galaxy has been published in the journal Nature, adding to the growing body of knowledge about the early universe.
The discovery of Maisie’s galaxy by the James Webb Space Telescope provides valuable insights into the early stages of the universe. By accurately estimating the galaxy’s age through redshift analysis, scientists can refine their understanding of cosmic evolution. The unexpected discoveries and challenges encountered during this research highlight the complexity of studying distant galaxies. As the JWST continues to explore the cosmos, it promises to unveil more secrets about our cosmic origins and the formation of celestial objects.