Candidate gravitationally lensed submillimeter galaxies in Herschel-ATLAS associated with WISE elliptical counterparts

¹ Departamento de Fisica, Universidad de Oviedo, C. Federico Garcia Lorca 18, 33007 Oviedo, Spain
² Instituto Universitario de Ciencias y Tecnologías Espaciales de Asturias (ICTEA), C. Independencia 13, 33004 Oviedo, Spain
³ SISSA, Via Bonomea 265, 34136 Trieste, Italy
⁴ IFPU – Institute for fundamental physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
⁵ Department of Space, Earth, & Environment, Chalmers University of Technology, Chalmersplatsen 4, Gothenburg, SE-412 96 Sweden
⁶ Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
⁷ Universidad de La Laguna, Departamento de Astrofísica, E-38206 La Laguna, Tenerife, Spain

^⋆ Corresponding author: canojuan@uniovi.es

Received: 15 May 2025
Accepted: 5 August 2025

Abstract

Aims. We present a new and independent methodology for identifying gravitational lens candidates using data from the H-ATLAS and AllWISE surveys. Unlike previous approaches, which are typically biased toward bright, strongly lensed submillimeter galaxies (SMGs), our method uncovers fainter systems with lower magnifications. This enables the identification and individual study of lensing events that would otherwise only be accessible through statistical weak lensing analyses.

Methods. Our approach focuses on high-redshift SMGs from H-ATLAS in the range 1.2 < z < 4.0, and searches for associated AllWISE sources within an angular distance of 18 arcsec. Candidate lenses are selected based on their WISE colors (0.5 < W2 − W3 < 1.5 mag), consistent with those of elliptical galaxies, and further filtered using J − W1 color and photometric redshift cuts to reduce stellar contamination. This conservative selection yields 68 new lens candidates. We then performed SED fitting with CIGALE across UV to submillimeter wavelengths to estimate the physical properties of both the lenses and the background SMGs, and to assess the lensing nature of these candidates.

Results. Despite the uncertainties, we were able to constrain key parameters such as stellar and dust masses, infrared luminosities, and star formation rates. In addition, the estimated magnifications for most candidates are modest, consistent with the weak lensing regime (μ ≃ 1 − 1.5), although a few sources may require more precise modeling. Future efforts could refine this methodology to recover potential candidates outside our selection, and high-resolution follow-up observations will be essential to confirm the lensing nature of these sources and to further investigate their physical properties.