COOL-LAMPS. IX. A Rare Duo of Quasars Each Lensed by a Single Massive Galaxy Cluster

@article{solhaug2026coollamps,
  title = {{COOL-LAMPS. IX. A Rare Duo of Quasars Each Lensed by a Single Massive Galaxy Cluster}},
  author = {Erik Solhaug and Michael D. Gladders and Andi M. Kisare and Simon D. Mork and Kunwanhui Niu and Matthew B. Bayliss and Aidan P. Cloonan and Håkon Dahle and Isaiah R. Escapa and Michael K. Florian and Josh Garza and Gourav Khullar and Guillaume Mahler and Natalie Malagon and Kate Napier and Allison Noble and Jane R. Rigby and T. Emil Rivera-Thorsen and Riley Rosener and Keren Sharon and Antony A. Stark and Jamar Sullivan and Marie Tagliavia and Raul Teixeira and Kabelo Tsiane and Grace C. Wagner and Brian Welch and Yifan “Megan” Zhao},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/ae9d70},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9d70},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - COOL-LAMPS. IX. A Rare Duo of Quasars Each Lensed by a Single Massive Galaxy Cluster
AU  - Erik Solhaug
AU  - Michael D. Gladders
AU  - Andi M. Kisare
AU  - Simon D. Mork
AU  - Kunwanhui Niu
AU  - Matthew B. Bayliss
AU  - Aidan P. Cloonan
AU  - Håkon Dahle
AU  - Isaiah R. Escapa
AU  - Michael K. Florian
AU  - Josh Garza
AU  - Gourav Khullar
AU  - Guillaume Mahler
AU  - Natalie Malagon
AU  - Kate Napier
AU  - Allison Noble
AU  - Jane R. Rigby
AU  - T. Emil Rivera-Thorsen
AU  - Riley Rosener
AU  - Keren Sharon
AU  - Antony A. Stark
AU  - Jamar Sullivan
AU  - Marie Tagliavia
AU  - Raul Teixeira
AU  - Kabelo Tsiane
AU  - Grace C. Wagner
AU  - Brian Welch
AU  - Yifan “Megan” Zhao
PY  - 2026
DA  - 2026/10/14
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae9d70
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/ae9d70
AB  - Wide-separation lensed quasars (WSLQs) are rare systems that arise from the chance alignment of two objects: a galaxy cluster and a background quasar. After two decades, only seven WSLQs have been found. Here, we report the discovery of COOL J1153+0755 by the COOL-LAMPS collaboration in DECaLS imaging and its confirmation with follow-up observations with the Magellan Telescopes and the Nordic Optical Telescope. This system features two multiply imaged quasars each lensed into four images by the same z = 0.4301 cluster: a classic broad-line Type I quasar at z = 1.524 (COOL J1153A) and a dust-obscured Type II quasar at z = 1.939 (COOL J1153B), with maximum image separations of 25 . ″ 6 and 26 . ″ 0 , respectively. We construct a lens model to estimate a projected cluster mass of M ( < 500 kpc) ∼ 3.3 × 10 ¹⁴ M ⊙ and relative time delays between the three brightest images of each quasar of Δ t A3, A1 ∼ 800, Δ t A2, A1 ∼ 1200, Δ t B1, B3 ∼ 800, and Δ t B2, B3 ∼ 1000 days. COOL J1153A resides in a dense environment with three nearby galaxies, two of which are also strongly lensed. We identified COOL J1153+0755 without making a morphological cut in the DECaLS catalog; none of its multiple images are classified as point sources in those data, implying that morphology-based selection would miss such systems. COOL J1153+0755 expands the WSLQ sample from seven to eight systems (nine individual quasars), adding two powerful laboratories for probing black hole-galaxy coevolution at Cosmic Noon and for time-delay cosmography constraints on the Hubble constant, H ₀ .
SN  - 0004-637X
SN  - 1538-4357
ER  -