Strong-lensing Analysis of SPT-CL J2325−4111 and SPT-CL J0049−2440, Two Powerful Cosmic Telescopes ( R E > 40″) from the SPT Clusters Sample

Mahler, Guillaume; Sharon, Keren; Bayliss, Matthew; Bleem, Lindsey. E.; Brodwin, Mark; Floyd, Benjamin; Gassis, Raven; Gladders, Michael D.; Khullar, Gourav; Remolina González, Juan D.; Sarkar, Arnab

Abstract

We report the results from a study of two massive (M500c > 6.0 × 1014 M⊙) strong-lensing clusters selected from the South Pole Telescope cluster survey for their large Einstein radius (RE > 40″), SPT-CL J2325−4111 and SPT-CL J0049−2440. Ground-based and shallow Hubble Space Telescope (HST) imaging indicated extensive strong-lensing evidence in these fields, with giant arcs spanning 18″ and 31″, respectively, motivating further space-based imaging follow-up. Here, we present multiband HST imaging and ground-based Magellan spectroscopy of the fields, from which we compile detailed strong-lensing models. The lens models of SPT-CL J2325−4111 and SPT-CL J0049−2440 were optimized using nine and eight secure multiply imaged systems with a final image-plane rms of 0 .″ 63 and 0 .″ 73, respectively. From the lensing analysis, we measure a projected mass density within 500 kpc of M(<500 kpc) = (7.30 ± 0.07) × 1014 M⊙ and M(<500kpc)=7.12−0.19+0.16×1014 M⊙ for these two clusters, and subhalo mass ratios of 0.12 ± 0.01 and 0.21−0.05+0.07 , respectively. Both clusters produce a large area with high magnification (μ ≥ 3) for a source at z = 9, A|μ|≥3lens=4.93−0.04+0.03 arcmin2 and A|μ|≥3lens=3.64−0.10+0.14 arcmin2, respectively, placing them in the top tier of strong-lensing clusters. We conclude that these clusters are spectacular sightlines for further observations that will reduce the systematic uncertainties due to cosmic variance. This paper provides the community with two additional well-calibrated cosmic telescopes, as strong as the Frontier Fields and suitable for studies of the highly magnified background Universe.

Citation

Mahler, G., Sharon, K., Bayliss, M., Bleem, L. E., Brodwin, M., Floyd, B., Gassis, R., Gladders, M. D., Khullar, G., Remolina González, J. D., & Sarkar, A. (2025). Strong-lensing Analysis of SPT-CL J2325−4111 and SPT-CL J0049−2440, Two Powerful Cosmic Telescopes ( R E > 40″) from the SPT Clusters Sample. The Astrophysical Journal, 980(1), Article 48. https://doi.org/10.3847/1538-4357/ad9aa5

• Journal Article Type: Article
• Acceptance Date: Nov 24, 2024
• Online Publication Date: Feb 3, 2025
• Publication Date: Feb 10, 2025
• Deposit Date: Feb 10, 2025
• Publicly Available Date: Feb 10, 2025
• Journal: The Astrophysical Journal
• Electronic ISSN: 1538-4357
• Peer Reviewed: Peer Reviewed
• Volume: 980
• Issue: 1
• Article Number: 48
• DOI: https://doi.org/10.3847/1538-4357/ad9aa5
• Keywords: High-redshift galaxies, Galactic and extragalactic astronomy, Dark matter, Strong gravitational lensing, Galaxy clusters
• Public URL: https://durham-repository.worktribe.com/output/3474838