Webb's data confirms Maisie's Galaxy as oldest ever observed

The presence of this distant galaxy in the early universe was confirmed by Webb's latest spectroscopic examination. 
Mrigakshi Dixit
Spectroscopic observations reveal that Maisie’s galaxy was detected 390 million years after the Big Bang.
Spectroscopic observations reveal that Maisie’s galaxy was detected 390 million years after the Big Bang.

NASA/STScI/CEERS/TACC/The University of Texas at Austin/S. Finkelstein/M. Bagley  

A red blob spotted in the backdrop of a deep field image taken by the James Webb Space Telescope last year has now been identified as one of the universe's earliest galaxies.

Maisie's Galaxy dates to around 390 million years after the Big Bang (for comparison, the universe is approximately 13.77 billion years old). 

The galaxy was discovered in June 2022 during observations undertaken by the Cosmic Evolution Early Release Science Survey (CEERS).

Webb's spectroscopic examination

The presence of this distant galaxy in the early universe was confirmed by Webb's latest spectroscopic examination. 

“The exciting thing about Maisie’s Galaxy is that it was one of the first distant galaxies identified by JWST, and of that set, it’s the first to actually be spectroscopically confirmed,” said  Steven Finkelstein, a professor of astronomy at the University of Texas, Austin, and the principal investigator of CEERS, in an official release.

The galaxy was named after Finkelstein's daughter as it was discovered on her birthday.

The determination of a galaxy's distance from Earth, utilizing light emitted by it, is heavily dependent on the principle of redshift. Redshift arises when the wavelength of light is stretched, leading the light to move towards the red segment of the spectrum.

Within the context of the expanding universe, celestial entities have a tendency to move away from us. Consequently, when an object is in rapid motion away from Earth, light must traverse a greater distance to reach our planet. This phenomenon leads to the elongation of the light's wavelength, causing a shift toward the red end of the spectrum.

New redshift data

However, the researchers initially measured the redshift of this galaxy using a different method known as photometry, which measures the brightness of light in images using different frequency filters. 

This method measured redshift (marked by the letter z) to be around 12, corresponding to the galaxy forming roughly 366 million years after the Big Bang.

Further analysis with the JWST's spectroscopic instrument, NIRSpec, revealed a redshift of z=11.4 — 390 million years after the Big Bang. 

While this discovery doesn't align precisely with astronomers' initial estimations, it still stands as one of the four earliest galaxies that have been confirmed.

Last month, the Space Telescope Science Institute unveiled a stunning 3D visualization depicting the CEERS deep field, which concludes with a glimpse of Maisie's galaxy. 

The purpose of CEERS is to image a vast swath of space and collect data with Webb's equipment in order to better comprehend the characteristics and evolution of the first galaxies that emerged in the early chaotic universe.

The findings were published in the journal Nature.

Study Abstract:

During the first 500 million years of cosmic history, the first stars and galaxies formed, seeding the Universe with heavy elements and eventually reionizing the intergalactic medium (1; 2; 3). Observations with JWST have uncovered a surprisingly high abundance of candidates for early star-forming galaxies, with distances (redshifts, 𝑧z), estimated from multi-band photometry, as large as 𝑧≈16z≈16, far beyond pre-JWST limits (4; 5; 6; 7; 8; 9). While generally robust, such photometric redshifts can suffer from degeneracies and occasionally catastrophic errors. Spectroscopic measurement is required to validate these sources and to reliably quantify physical properties that can constrain galaxy formation models and cosmology (10). Here we present JWST spectroscopy that confirms redshifts for two very luminous galaxies with 𝑧>11z>11, but also demonstrates that another candidate with suggested 𝑧≈16z≈16 instead has 𝑧=4.9z=4.9, with an unusual combination of nebular line emission and dust reddening that mimics the colors expected for much more distant objects. These results reinforce evidence for the early, rapid formation of remarkably luminous galaxies, while also highlighting the necessity of spectroscopic verification. The large abundance of bright, early galaxies may indicate shortcomings in current galaxy formation models, or deviation from physical properties (such as the stellar initial mass function) that are generally believed to hold at later times.

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