Two extremely bright galaxies were captured in GLASS-JWST program. These galaxies existed approximately 450 and 350 million years after the Big Bang (with a redshift of approximately 10.5 and 12.5, respectively), and sizes are approximately 500 parsecs and 170 parsecs, respectively. Figure 2: Size– luminosity relationships of galaxies observed in 5 wavelength bands with fixed slope owing to restricted data. One study, led by Kavli IPMU JSPS Fellow Lilan Yang, and consisting of Project Researcher Xuheng Ding, utilized multiband NIRCAM imaging data from the GLASS-JWST program to measure galaxy size and luminosity to figure out the morphology and the size-luminosity relation from rest-frame optical to UV.
The scientists discovered the first rest-frame optical size-luminosity relation of galaxies at a redshift larger than 7, or approximately 800 million years after the Big Bang, allowing them to study the size as a function of wavelength.
Figure 2: Size– luminosity relationships of galaxies observed in 5 wavelength bands with repaired slope owing to limited information. One study, led by Kavli IPMU JSPS Fellow Lilan Yang, and including Project Researcher Xuheng Ding, utilized multiband NIRCAM imaging data from the GLASS-JWST program to determine galaxy size and luminosity to figure out the morphology and the size-luminosity relation from rest-frame optical to UV.
” Its the first time that we can study the galaxys homes in rest-frame optical at a redshift bigger than 7 with JWST, and the size-luminosity is very important for determining the shape of luminosity function which suggests the primary sources responsible for the cosmic reionization, i.e., many faint galaxies or relatively less bright galaxies.
” The initial wavelength of light will shift to a longer wavelength when it takes a trip from the early universe to us. Thus, the rest-frame wavelength is utilized to clarify their intrinsic wavelength, rather than the observed wavelength.
Previously, with Hubble Space Telescope, we know the properties of galaxies just in the rest-frame UV band. Now, with JWST, we can determine longer wavelength than UV,” said first author Yang.
The scientists found the first rest-frame optical size-luminosity relation of galaxies at a redshift larger than 7, or approximately 800 million years after the Big Bang, enabling them to study the size as a function of wavelength. They discovered the typical size at the reference luminosity is roughly 450-600 parsecs and reduced slightly from rest-frame optical to UV. Was this expected?
” The answer is we do not understand what to expect. Previous simulation research studies offer a variety of predictions,” stated Yang.
When enabling the slope to vary, the team likewise found the slope of the size– luminosity relationship was rather steeper in the shortest wavelength band.
” That would suggest greater surface brightness density at shorter wavelength, thus less observational incompleteness correction when estimating luminosity function, however the result is not definitive. We do not desire to over-interpret here,” stated Yang.
Reference: “Early Results from GLASS-JWST. V: The First Rest-frame Optical Size– Luminosity Relation of Galaxies at z > > 7” by L. Yang, T. Morishita, N. Leethochawalit, M. Castellano, A. Calabrò, T. Treu, A. Bonchi, A. Fontana, C. Mason, E. Merlin, D. Paris, M. Trenti, G. Roberts-Borsani, M. Bradac, E. Vanzella, B. Vulcani, D. Marchesini, X. Ding, T. Nanayakkara, S. Birrer, K. Glazebrook, T. Jones, K. Boyett, P. Santini, V. Strait and X. Wang, 18 October 2022, The Astrophysical Journal Letters.DOI: 10.3847/ 2041-8213/ ac8803.
Figure 1. 2 exceptionally intense galaxies were caught in GLASS-JWST program. These galaxies existed roughly 450 and 350 million years after the Big Bang (with a redshift of around 10.5 and 12.5, respectively), and sizes are roughly 500 parsecs and 170 parsecs, respectively. Credit: NASA, ESA, CSA, Tommaso Treu (UCLA).
An international group of researchers, including those from the Kavli Institute for the Physics and Mathematics of deep space (Kavli IPMU), have released a brand-new research study in The Astrophysical Journal Letters that examines the relationship in between the size and luminosity of a few of the earliest galaxies in deep space, as captured by the just recently released James Webb Space Telescope (JWST)– less than a billion years after the Big Bang.
The findings become part of the Grim Lens-Amplified Survey from Space (GLASS) Early-Release Science Program, led by Professor Tommaso Treu from the University of California, Los Angeles. The programs aim is to study the early universe when the very first stars and galaxies ignited, resulting in the ionization of neutral gas and the development of light, called the date of reionization.
Details of reionization have stayed unidentified due to the fact that telescopes till today have not been capable of observing galaxies in this duration of the universes history in information. Finding out more about the date of reionization would help scientists understand how galaxies and stars have actually evolved to develop todays universe as we see it.
By Kavli Institute for the Physics and Mathematics of the Universe
February 24, 2023
