This JWST image shows the galaxy cluster SMACS J0723.3−7327 with a large number of lensed background galaxies. The white bar at the bottom corresponds to 50 arcseconds, which is roughly the maximum size of Jupiter as seen from Earth. Credits: NASA, ESA, CSA and STScI
Using the first scientific image released by the James Webb Space Telescope (JWST) this month, an international team of scientists with a major contribution from the Technical University of Munich (TUM) has built an improved model for the mass distribution of the SMACS galaxy cluster J0723. .3−7327. Acting as a so-called gravitational lens, the foreground galaxy cluster produces multiple images of background galaxies and magnifies these images. One family of these multiple images belongs to a galaxy, which the model predicts is about 13 Gyrs away, meaning its light traveled about 13 billion years before reaching the telescope .
The first scientific image released by the James Webb Space Telescope (JWST) was of gravitational lensing, in particular of the galaxy cluster SMACS J0723.3−7327. Gravitational lensing, especially by galaxy clusters, magnifies the light of background galaxies and produces multiple images of them. Before JWST, 19 multiple images of six background sources were known in SMACS J0723.3−7327. The JWST data now revealed an additional 27 multiple images from ten other lensed sources.
“In this first step towards the road opened by JWST, we have used recent data from this new telescope, to model the lensing effect of SMACS0723 with great precision”, notes Gabriel Bartosch Caminha, TUM postdoctoral fellow, the Institute Max Planck Astrophysics (MPA) and the German Center for Cosmological Lenses (GCCL). The collaboration first used data from the Hubble Space Telescope (HST) and the Multiple Unit Spectroscopic Explorer (MUSE) to build a “pre-JWST” lens model, then refined it with infrared images upcoming newly available JWSTs. “The JWST image is absolutely stunning and beautiful, showing many more multilensed background sources, which allowed us to substantially refine our lensing mass model,” he adds.
In this image, the various multilensed background galaxies are numbered, with cyan colors indicating already known multiple imaging systems and green colors indicating new multilensed sources. The insets show magnified images of a very distant galaxy with some substructure indicated by the green arrows. Credits: NASA, ESA, CSA and STScI (MPA annotations)
One of the most accurate models available
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 was found to be probably at a surprising distance of 13 Gyrs (redshift > 7.5), meaning its light was emitted during the early stages of the universe. This galaxy is multiplied in three images and its luminosity is magnified by a factor of μ≈20 in total.
However, to study these primordial objects, it is critical to accurately describe the lensing effect of the foreground galaxy cluster. “Our accurate mass model forms the basis for the exploration of the JWST data,” emphasizes Sherry Suyu, professor of observational cosmology at TUM, leader of the Max Planck research group at MPA and visiting researcher at the Institute of Astronomy and Astrophysics of the Sinica Academy. “The spectacular JWST images show a wide variety of strongly lensed galaxies, which can be studied in detail thanks to our accurate model.”
The new model for the mass distribution of the foreground cluster is able to reproduce the positions of all multiple images with high accuracy, making the model one of the most accurate available. For follow-up studies of these sources, lensing models, including magnification maps and redshifts (i.e. distances) estimated from the model are made publicly available. “We are very excited about it,” adds Suyu. “We look forward to future JWST observations of other strongly lensed galaxy clusters. This will not only allow us to better constrain the mass distributions of galaxy clusters, but also study high-redshift galaxies.”
How the James Webb Space Telescope lets us see the universe’s first galaxies More information: GB Caminha et al, First JWST observations of a gravitational lens: new multi-imaging massive model with near-infrared observations of SMACS~J0723. 3−7327. arXiv:2207.07567v1 [astro-ph.GA]arxiv.org/abs/2207.07567 Provided by the Technical University of Munich
Citation: Improved model for the mass distribution of the galaxy cluster SMACS J0723.3−7327 based on the Webb Telescope image (2022 July 28) retrieved 2022 July 28 from
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