Using the first scientific image released by the James Webb Space Telescope (JWST) this month, an international team led by scientists from the Max Planck Institute for Astrophysics (MPA) and the Technical University of Munich (TUM) built an improved model of the galactic mass distribution cluster SMACS J0723.3−7327. They used dozens of multiple images of distant background galaxies revealed in the JWST image, some of which were too faint to be detected before. Acting as a so-called gravitational lens, the foreground galaxy cluster both creates multiple images of background galaxies and magnifies those images. One family of such multiple images belongs to a galaxy modeled at a distance of about 13 Gyr, ie. whose light traveled about 13 billion years before reaching the telescope.
The first science image released by the James Webb Space Telescope (JWST) was of gravitational lensing, specifically the galaxy cluster SMACS J0723.3−7327. Gravitational lensing, especially galaxy clusters, magnifies light from background galaxies and creates multiple images of them. Prior to JWST, 19 multiple images of six background sources were known in SMACS J0723.3−7327. The JWST data have now revealed 27 additional multiple images from ten other lensed sources.
“In this first step towards the path discovered by JWST, we used recent data from this brand new telescope to model the lensing effect of SMACS0723 with great accuracy,” points out Gabriel Bartosz Kamiña, a postdoctoral fellow at the Max Planck Institute for Astrophysics (MPA). , the Technical University of Munich and the German Center for Cosmological Lenses (GCCL). The collaboration first used data from the Hubble Space Telescope (HST) and the Multi Unit Spectroscopic Explorer (MUSE) to build a “pre-JWST” lens model and then refined it with newly available JWST near-infrared imaging. “The JWST image is absolutely stunning and beautiful, showing many more multi-lensing background sources, which allowed us to greatly refine our lensing mass model,” he adds.
Many of these new lensed sources do not yet have distance estimates, and the scientists used their mass model to predict how far away these lensed galaxies are most likely to be. One of them is found to be probably at the astonishing distance of 13 Gyr (redshift > 7.5), ie. its light was emitted during the early stages of the universe. This galaxy has been repeatedly objectified in three images and its brightness has been magnified in total by a factor of μ≈20.
However, to study these primary objects, it is essential to accurately describe the lensing effect of the foreground galaxy cluster. “Our accurate mass model forms the basis for studying the JWST data,” emphasizes Sherry Suyu, Professor of Observational Cosmology at TUM, Head of the Max Planck Research Group at the MPA and Visiting Scientist at the Institute for Astronomy and Astrophysics Academia Sinica. “JWST’s spectacular images show a wide variety of strong lensing galaxies that can be studied in detail thanks to our accurate model.”
The new foreground cluster mass distribution model is capable of reproducing the positions of all multiple images with high accuracy, making the model one of the most accurate available. For subsequent studies of these sources, the lensing models, including the magnification maps and redshifts (i.e., distances) calculated from the model, are publicly available. “We are very excited about this,” adds Suyu, “we look forward to future JWST observations of other strong lensing galaxy clusters. This will not only allow us to better constrain the mass distribution of galaxy clusters, but also to study high-redshift galaxies.
Title of the article
First JWST observations of gravitational lensing: Mass model of new near-infrared imaging multiples of SMACS~J0723.3−7327
Date of publication of the article
July 15, 2022
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