Euclid Quick Data Release (Q1): XXIX. The Strong Lensing Discovery Engine D - Double-source-plane lens candidates

Euclid Collaboration; T. E. Collett; W. J. R. Enzi; C. Krawczyk; E. Gaztanaga; S. Nadathur; K. Naidoo

doi:10.1051/0004-6361/202554543

Euclid Quick Data Release (Q1): XXIX. The Strong Lensing Discovery Engine D - Double-source-plane lens candidates

Euclid Collaboration
, T. E. Collett
, W. J. R. Enzi
, C. Krawczyk
, E. Gaztanaga
, S. Nadathur
, K. Naidoo

Institute of Cosmology & Gravitation

Research output: Contribution to journal › Article › peer-review

Abstract

Strong gravitational-lensing systems with multiple source planes are powerful tools for probing the density profiles and dark matter substructure of galaxies. The ratio of the Einstein radii is related to the dark energy equation of state through the cosmological scaling factor β. Galaxy-scale double-source-plane lenses (DSPLs) are extremely rare, however. We report the discovery of four new galaxy-scale DSPL candidates in the Euclid Quick Release 1 (Q1) data. These systems were initially identified through a combination of machine-learning lens-finding models and subsequent visual inspection from citizens and experts. We applied the widel -used LensPop lens-forecasting model to predict that the full Euclid survey will discover 1700 DSPLs. This scales to 6 ± 3 DSPLs in 63 deg2, which is the area of Q1. The number of discoveries in this work is broadly consistent with this forecast. We present lens models for each DSPL and infer their β values. Our initial Q1 sample demonstrates that Euclid promises to discover these rare objects.

Original language	English
Article number	A29
Number of pages	15
Journal	Astronomy and Astrophysics
Volume	711
Early online date	30 Jun 2026
DOIs	https://doi.org/10.1051/0004-6361/202554543
Publication status	Published - 1 Jul 2026

Keywords

astro-ph.GA
Gravitational lensing: strong
Galaxies: halos
dark matter

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10.1051/0004-6361/202554543

Euclid Quick Data Release (Q1) XXIXFinal published version, 3.74 MBLicence: CC BY

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title = "Euclid Quick Data Release (Q1): XXIX. The Strong Lensing Discovery Engine D - Double-source-plane lens candidates",

abstract = "Strong gravitational-lensing systems with multiple source planes are powerful tools for probing the density profiles and dark matter substructure of galaxies. The ratio of the Einstein radii is related to the dark energy equation of state through the cosmological scaling factor β. Galaxy-scale double-source-plane lenses (DSPLs) are extremely rare, however. We report the discovery of four new galaxy-scale DSPL candidates in the Euclid Quick Release 1 (Q1) data. These systems were initially identified through a combination of machine-learning lens-finding models and subsequent visual inspection from citizens and experts. We applied the widel -used LensPop lens-forecasting model to predict that the full Euclid survey will discover 1700 DSPLs. This scales to 6 ± 3 DSPLs in 63 deg2, which is the area of Q1. The number of discoveries in this work is broadly consistent with this forecast. We present lens models for each DSPL and infer their β values. Our initial Q1 sample demonstrates that Euclid promises to discover these rare objects.",

keywords = "astro-ph.GA, Gravitational lensing: strong, Galaxies: halos, dark matter",

author = "\{Euclid Collaboration\} and Euclid Collaboration and T. Li and Collett, \{T. E.\} and M. Walmsley and Lines, \{N. E. P.\} and K. Rojas and Nightingale, \{J. W.\} and Enzi, \{W. J. R.\} and Moustakas, \{L. A.\} and C. Krawczyk and R. Gavazzi and G. Despali and P. Holloway and S. Schuldt and F. Courbin and Metcalf, \{R. B.\} and Ballard, \{D. J.\} and A. Verma and B. Cl{\'e}ment and H. Degaudenzi and A. Melo and Barroso, \{J. A. Acevedo\} and L. Leuzzi and A. Manj{\'o}n-Garc{\'i}a and R. Pearce-Casey and D. Sluse and C. Tortora and R. Massey and G. Mahler and A. More and N. Aghanim and B. Altieri and A. Amara and S. Andreon and N. Auricchio and H. Aussel and C. Baccigalupi and M. Baldi and A. Balestra and S. Bardelli and P. Battaglia and R. Bender and F. Bernardeau and S. Casas and Nichol, \{R. C.\} and Percival, \{W. J.\} and Schewtschenko, \{J. A.\} and E. Gaztanaga and S. Nadathur and K. Naidoo",

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doi = "10.1051/0004-6361/202554543",

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T1 - Euclid Quick Data Release (Q1): XXIX. The Strong Lensing Discovery Engine D - Double-source-plane lens candidates

AU - Euclid Collaboration

AU - Collaboration, Euclid

AU - Li, T.

AU - Collett, T. E.

AU - Walmsley, M.

AU - Lines, N. E. P.

AU - Rojas, K.

AU - Nightingale, J. W.

AU - Enzi, W. J. R.

AU - Moustakas, L. A.

AU - Krawczyk, C.

AU - Gavazzi, R.

AU - Despali, G.

AU - Holloway, P.

AU - Schuldt, S.

AU - Courbin, F.

AU - Metcalf, R. B.

AU - Ballard, D. J.

AU - Verma, A.

AU - Clément, B.

AU - Degaudenzi, H.

AU - Melo, A.

AU - Barroso, J. A. Acevedo

AU - Leuzzi, L.

AU - Manjón-García, A.

AU - Pearce-Casey, R.

AU - Sluse, D.

AU - Tortora, C.

AU - Massey, R.

AU - Mahler, G.

AU - More, A.

AU - Aghanim, N.

AU - Altieri, B.

AU - Amara, A.

AU - Andreon, S.

AU - Auricchio, N.

AU - Aussel, H.

AU - Baccigalupi, C.

AU - Baldi, M.

AU - Balestra, A.

AU - Bardelli, S.

AU - Battaglia, P.

AU - Bender, R.

AU - Bernardeau, F.

AU - Casas, S.

AU - Nichol, R. C.

AU - Percival, W. J.

AU - Schewtschenko, J. A.

AU - Gaztanaga, E.

AU - Nadathur, S.

AU - Naidoo, K.

N1 - DOI not yet working - navigating to a 'forbidden' message on the journal website 10.1051/0004-6361/202554543 Paper submitted as part of the A&A Special Issue `Euclid Quick Data Release (Q1), 16 pages, 11 figures

PY - 2026/7/1

Y1 - 2026/7/1

N2 - Strong gravitational-lensing systems with multiple source planes are powerful tools for probing the density profiles and dark matter substructure of galaxies. The ratio of the Einstein radii is related to the dark energy equation of state through the cosmological scaling factor β. Galaxy-scale double-source-plane lenses (DSPLs) are extremely rare, however. We report the discovery of four new galaxy-scale DSPL candidates in the Euclid Quick Release 1 (Q1) data. These systems were initially identified through a combination of machine-learning lens-finding models and subsequent visual inspection from citizens and experts. We applied the widel -used LensPop lens-forecasting model to predict that the full Euclid survey will discover 1700 DSPLs. This scales to 6 ± 3 DSPLs in 63 deg2, which is the area of Q1. The number of discoveries in this work is broadly consistent with this forecast. We present lens models for each DSPL and infer their β values. Our initial Q1 sample demonstrates that Euclid promises to discover these rare objects.

AB - Strong gravitational-lensing systems with multiple source planes are powerful tools for probing the density profiles and dark matter substructure of galaxies. The ratio of the Einstein radii is related to the dark energy equation of state through the cosmological scaling factor β. Galaxy-scale double-source-plane lenses (DSPLs) are extremely rare, however. We report the discovery of four new galaxy-scale DSPL candidates in the Euclid Quick Release 1 (Q1) data. These systems were initially identified through a combination of machine-learning lens-finding models and subsequent visual inspection from citizens and experts. We applied the widel -used LensPop lens-forecasting model to predict that the full Euclid survey will discover 1700 DSPLs. This scales to 6 ± 3 DSPLs in 63 deg2, which is the area of Q1. The number of discoveries in this work is broadly consistent with this forecast. We present lens models for each DSPL and infer their β values. Our initial Q1 sample demonstrates that Euclid promises to discover these rare objects.

KW - astro-ph.GA

KW - Gravitational lensing: strong

KW - Galaxies: halos

KW - dark matter

U2 - 10.1051/0004-6361/202554543

DO - 10.1051/0004-6361/202554543

M3 - Article

SN - 0004-6361

VL - 711

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A29

ER -

Euclid Quick Data Release (Q1): XXIX. The Strong Lensing Discovery Engine D - Double-source-plane lens candidates

Abstract

Keywords

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