Euclid: A complete Einstein ring in NGC 6505

C. M. O'Riordan; L. J. Oldham; A. Nersesian; T. Li; T. E. Collett; D. Sluse; B. Altieri; B. Clément; K. G.C. Vasan; S. Rhoades; Y. Chen; T. Jones; C. Adami; R. Gavazzi; S. Vegetti; D. M. Powell; J. A. Acevedo Barroso; I. T. Andika; R. Bhatawdekar; A. R. Cooray; G. Despali; J. M. Diego; L. R. Ecker; A. Galan; P. Gómez-Alvarez; L. Leuzzi; M. Meneghetti; R. B. Metcalf; M. Schirmer; S. Serjeant; C. Tortora; M. Vaccari; G. Vernardos; M. Walmsley; A. Amara; S. Andreon; N. Auricchio; H. Aussel; C. Baccigalupi; M. Baldi; A. Balestra; S. Bardelli; A. Basset; P. Battaglia; R. Bender; D. Bonino; E. Branchini; M. Brescia; J. Brinchmann; A. Caillat; S. Camera; V. Capobianco; C. Carbone; J. Carretero; S. Casas; F. J. Castander; M. Castellano; G. Castignani; S. Cavuoti; A. Cimatti; C. Colodro-Conde; G. Congedo; C. J. Conselice; L. Conversi; Y. Copin; L. Corcione; F. Courbin; H. M. Courtois; M. Cropper; A. Da Silva; H. Degaudenzi; G. De Lucia; A. M. Di Giorgio; J. Dinis; F. Dubath; C. A.J. Duncan; X. Dupac; S. Dusini; M. Farina; S. Farrens; F. Faustini; S. Ferriol; N. Fourmanoit; M. Frailis; E. Franceschi; M. Fumana; S. Galeotta; W. Gillard; B. Gillis; C. Giocoli; B. R. Granett; A. Grazian; F. Grupp; L. Guzzo; S. V.H. Haugan; J. Hoar; H. Hoekstra; W. Holmes; I. Hook; F. Hormuth; A. Hornstrup; P. Hudelot; K. Jahnke; M. Jhabvala; B. Joachimi; E. Keihänen; S. Kermiche; A. Kiessling; M. Kilbinger; R. Kohley; B. Kubik; M. Kümmel; M. Kunz; H. Kurki-Suonio; O. Lahav; R. Laureijs; D. Le Mignant; S. Ligori; P. B. Lilje; V. Lindholm; I. Lloro; G. Mainetti; E. Maiorano; O. Mansutti; O. Marggraf; K. Markovic; M. Martinelli; N. Martinet; F. Marulli; R. Massey; E. Medinaceli; S. Mei; M. Melchior; Y. Mellier; E. Merlin; G. Meylan; M. Moresco; L. Moscardini; R. Nakajima; R. C. Nichol; S. M. Niemi; J. W. Nightingale; C. Padilla; S. Paltani; F. Pasian; K. Pedersen; W. J. Percival; V. Pettorino; S. Pires; G. Polenta; M. Poncet; L. A. Popa; L. Pozzetti; F. Raison; R. Rebolo; A. Renzi; J. Rhodes; G. Riccio; H. W. Rix; E. Romelli; M. Roncarelli; E. Rossetti; B. Rusholme; R. Saglia; Z. Sakr; A. G. Sánchez; D. Sapone; B. Sartoris; P. Schneider; T. Schrabback; A. Secroun; G. Seidel; S. Serrano; C. Sirignano; G. Sirri; L. Stanco; J. Steinwagner; P. Tallada-Crespí; I. Tereno; R. Toledo-Moreo; F. Torradeflot; I. Tutusaus; L. Valenziano; T. Vassallo; G. Verdoes Kleijn; A. Veropalumbo; Y. Wang; J. Weller; A. Zacchei; G. Zamorani; E. Zucca; C. Burigana; P. Casenove; A. Mora; V. Scottez; M. Viel; M. Jauzac; H. Dannerbauer

doi:10.1051/0004-6361/202453014

Euclid: A complete Einstein ring in NGC 6505

C. M. O'Riordan^*
, L. J. Oldham
, A. Nersesian
, T. Li
, T. E. Collett
, D. Sluse
, B. Altieri
, B. Clément
, K. G.C. Vasan
, S. Rhoades
, Y. Chen
, T. Jones
, C. Adami
, R. Gavazzi
, S. Vegetti
, D. M. Powell
, J. A. Acevedo Barroso
, I. T. Andika
, R. Bhatawdekar
, A. R. Cooray

G. Despali, J. M. Diego, L. R. Ecker, A. Galan, P. Gómez-Alvarez, L. Leuzzi, M. Meneghetti, R. B. Metcalf, M. Schirmer, S. Serjeant, C. Tortora, M. Vaccari, G. Vernardos, M. Walmsley, A. Amara, S. Andreon, N. Auricchio, H. Aussel, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, A. Basset, P. Battaglia, R. Bender, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, A. Caillat, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, F. J. Castander, M. Castellano, G. Castignani, S. Cavuoti, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, L. Corcione, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, A. M. Di Giorgio, J. Dinis, F. Dubath, C. A.J. Duncan, X. Dupac, S. Dusini, M. Farina, S. Farrens, F. Faustini, S. Ferriol, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, W. Gillard, B. Gillis, C. Giocoli, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V.H. Haugan, J. Hoar, H. Hoekstra, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, R. Kohley, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, O. Lahav, R. Laureijs, D. Le Mignant, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, M. Martinelli, N. Martinet, F. Marulli, R. Massey, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, E. Merlin, G. Meylan, M. Moresco, L. Moscardini, R. Nakajima, R. C. Nichol, S. M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, H. W. Rix, E. Romelli, M. Roncarelli, E. Rossetti, B. Rusholme, R. Saglia, Z. Sakr, A. G. Sánchez, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, C. Sirignano, G. Sirri, L. Stanco, J. Steinwagner, P. Tallada-Crespí, I. Tereno, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, E. Zucca, C. Burigana, P. Casenove, A. Mora, V. Scottez, M. Viel, M. Jauzac, H. Dannerbauer

^*Corresponding author for this work

Max Planck Institute for Astrophysics
University of Portsmouth
Ghent University
European Space Astronomy Centre
Swiss Federal Institute of Technology Lausanne
University of California at Davis
CNRS
Institut d’Astrophysique de Paris
Technical University of Munich
University of California at Irvine
National Institute for Nuclear Physics
CSIC-UC - Institute of Physics of Cantabria
Max Planck Institute for Extraterrestrial Physics
University of Bologna
Max Planck Institute for Astronomy
Open University Milton Keynes
Osservatorio Astronomico di Capodimonte
Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
City University of New York
University of Toronto
University of Surrey
Osservatorio Astronomico di Brera
Université Paris-Saclay
University of Trieste
Astronomical Observatory of Padua
Centre national d'études spatiales
National Institute for Astrophysics
University of Genoa
University of Naples Federico II
University of Porto
University of Turin
Port d’Informació Científica
CSIC - Institute of Space Sciences
Osservatorio Astronomico Roma
Instituto de Astrofísica de Canarias
University of Edinburgh
University of Manchester
Universite Claude Bernard Lyon 1
University of Barcelona
Institut national de physique nucléaire et de physique des particules
University College London
University of Lisbon
University of Geneva
Osservatorio Astronomico di Trieste
Italian Space Agency
Ludwig Maximilian University of Munich
University of Milan
University of Oslo
Leiden University
California Institute of Technology
Lancaster University
Felix Hormuth Engineering
NASA Goddard Space Flight Center
University of Helsinki
University of Groningen
Netherlands Institute for Radio Astronomy
University of Bonn
Durham University
Université Paris 7
University of Applied Sciences Northwestern Switzerland
ESTEC
Newcastle University
Institute for High Energy Physics
University of Copenhagen
University of Waterloo
Institute of Space Science
University of La Laguna
University of Padua
Heidelberg University
Universidad de Chile
University of Innsbruck
Institute of Space Studies of Catalonia
Technical University of Cartagena
CIEMAT
Université Paul Sabatier Toulouse III
European Space Agency - ESA
Université catholique de Lille
International School for Advanced Studies

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (I_E = 18.1 lensed, I_E = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by Euclid. We present deep imaging data of the lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the Keck Cosmic Web Imager (KCWI). The Euclid imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of z = 0.406. Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of σ_∗ = 303 ± 15 km s^-1. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of 2.″5, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, R_eff ∼ 12.″3. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of f_DM = (11.1_-3.5^+5.4)% and a stellar initial mass-function (IMF) mismatch parameter of α_IMF = 1.26_-0.08^+0.05, indicating a heavier-than-Chabrier IMF in the centre of the galaxy.

Original language	English
Article number	A145
Journal	Astronomy and Astrophysics
Volume	694
Number of pages	13
ISSN	0004-6361
DOIs	https://doi.org/10.1051/0004-6361/202453014
Publication status	Published - 2025

Keywords

Galaxies: individual: NGC 6505
Gravitational lensing: strong
Surveys

Access to Document

10.1051/0004-6361/202453014Licence: CC BY

FulltextFinal published version, 11.7 MBLicence: CC BY

OpenUrl availability

Check availability in DTU Findit

Cite this

O'Riordan, C. M., Oldham, L. J., Nersesian, A., Li, T., Collett, T. E., Sluse, D., Altieri, B., Clément, B., Vasan, K. G. C., Rhoades, S., Chen, Y., Jones, T., Adami, C., Gavazzi, R., Vegetti, S., Powell, D. M., Acevedo Barroso, J. A., Andika, I. T., Bhatawdekar, R., ... Dannerbauer, H. (2025). Euclid: A complete Einstein ring in NGC 6505. Astronomy and Astrophysics, 694, Article A145. https://doi.org/10.1051/0004-6361/202453014

@article{20031706d2eb4ba3a9cdad1868fb52c3,

title = "Euclid: A complete Einstein ring in NGC 6505",

abstract = "We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (IE = 18.1 lensed, IE = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by Euclid. We present deep imaging data of the lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the Keck Cosmic Web Imager (KCWI). The Euclid imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of z = 0.406. Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of σ∗ = 303 ± 15 km s-1. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of 2.″5, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, Reff ∼ 12.″3. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of fDM = (11.1-3.5+5.4)\% and a stellar initial mass-function (IMF) mismatch parameter of αIMF = 1.26-0.08+0.05, indicating a heavier-than-Chabrier IMF in the centre of the galaxy.",

keywords = "Galaxies: individual: NGC 6505, Gravitational lensing: strong, Surveys",

author = "O'Riordan, \{C. M.\} and Oldham, \{L. J.\} and A. Nersesian and T. Li and Collett, \{T. E.\} and D. Sluse and B. Altieri and B. Cl{\'e}ment and Vasan, \{K. G.C.\} and S. Rhoades and Y. Chen and T. Jones and C. Adami and R. Gavazzi and S. Vegetti and Powell, \{D. M.\} and \{Acevedo Barroso\}, \{J. A.\} and Andika, \{I. T.\} and R. Bhatawdekar and Cooray, \{A. R.\} and G. Despali and Diego, \{J. M.\} and Ecker, \{L. R.\} and A. Galan and P. G{\'o}mez-Alvarez and L. Leuzzi and M. Meneghetti and Metcalf, \{R. B.\} and M. Schirmer and S. Serjeant and C. Tortora and M. Vaccari and G. Vernardos and M. Walmsley 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 A. Basset and P. Battaglia and R. Bender and D. Bonino and E. Branchini and M. Brescia and J. Brinchmann and A. Caillat and S. Camera and V. Capobianco and C. Carbone and J. Carretero and S. Casas and Castander, \{F. J.\} and M. Castellano and G. Castignani and S. Cavuoti and A. Cimatti and C. Colodro-Conde and G. Congedo and Conselice, \{C. J.\} and L. Conversi and Y. Copin and L. Corcione and F. Courbin and Courtois, \{H. M.\} and M. Cropper and \{Da Silva\}, A. and H. Degaudenzi and \{De Lucia\}, G. and \{Di Giorgio\}, \{A. M.\} and J. Dinis and F. Dubath and Duncan, \{C. A.J.\} and X. Dupac and S. Dusini and M. Farina and S. Farrens and F. Faustini and S. Ferriol and N. Fourmanoit and M. Frailis and E. Franceschi and M. Fumana and S. Galeotta and W. Gillard and B. Gillis and C. Giocoli and Granett, \{B. R.\} and A. Grazian and F. Grupp and L. Guzzo and Haugan, \{S. V.H.\} and J. Hoar and H. Hoekstra and W. Holmes and I. Hook and F. Hormuth and A. Hornstrup and P. Hudelot and K. Jahnke and M. Jhabvala and B. Joachimi and E. Keih{\"a}nen and S. Kermiche and A. Kiessling and M. Kilbinger and R. Kohley and B. Kubik and M. K{\"u}mmel and M. Kunz and H. Kurki-Suonio and O. Lahav and R. Laureijs and \{Le Mignant\}, D. and S. Ligori and Lilje, \{P. B.\} and V. Lindholm and I. Lloro and G. Mainetti and E. Maiorano and O. Mansutti and O. Marggraf and K. Markovic and M. Martinelli and N. Martinet and F. Marulli and R. Massey and E. Medinaceli and S. Mei and M. Melchior and Y. Mellier and E. Merlin and G. Meylan and M. Moresco and L. Moscardini and R. Nakajima and Nichol, \{R. C.\} and Niemi, \{S. M.\} and Nightingale, \{J. W.\} and C. Padilla and S. Paltani and F. Pasian and K. Pedersen and Percival, \{W. J.\} and V. Pettorino and S. Pires and G. Polenta and M. Poncet and Popa, \{L. A.\} and L. Pozzetti and F. Raison and R. Rebolo and A. Renzi and J. Rhodes and G. Riccio and Rix, \{H. W.\} and E. Romelli and M. Roncarelli and E. Rossetti and B. Rusholme and R. Saglia and Z. Sakr and S{\'a}nchez, \{A. G.\} and D. Sapone and B. Sartoris and P. Schneider and T. Schrabback and A. Secroun and G. Seidel and S. Serrano and C. Sirignano and G. Sirri and L. Stanco and J. Steinwagner and P. Tallada-Cresp{\'i} and I. Tereno and R. Toledo-Moreo and F. Torradeflot and I. Tutusaus and L. Valenziano and T. Vassallo and \{Verdoes Kleijn\}, G. and A. Veropalumbo and Y. Wang and J. Weller and A. Zacchei and G. Zamorani and E. Zucca and C. Burigana and P. Casenove and A. Mora and V. Scottez and M. Viel and M. Jauzac and H. Dannerbauer",

note = "Publisher Copyright: {\textcopyright} The Authors 2025.",

year = "2025",

doi = "10.1051/0004-6361/202453014",

language = "English",

volume = "694",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

O'Riordan, CM, Oldham, LJ, Nersesian, A, Li, T, Collett, TE, Sluse, D, Altieri, B, Clément, B, Vasan, KGC, Rhoades, S, Chen, Y, Jones, T, Adami, C, Gavazzi, R, Vegetti, S, Powell, DM, Acevedo Barroso, JA, Andika, IT, Bhatawdekar, R, Cooray, AR, Despali, G, Diego, JM, Ecker, LR, Galan, A, Gómez-Alvarez, P, Leuzzi, L, Meneghetti, M, Metcalf, RB, Schirmer, M, Serjeant, S, Tortora, C, Vaccari, M, Vernardos, G, Walmsley, M, Amara, A, Andreon, S, Auricchio, N, Aussel, H, Baccigalupi, C, Baldi, M, Balestra, A, Bardelli, S, Basset, A, Battaglia, P, Bender, R, Bonino, D, Branchini, E, Brescia, M, Brinchmann, J, Caillat, A, Camera, S, Capobianco, V, Carbone, C, Carretero, J, Casas, S, Castander, FJ, Castellano, M, Castignani, G, Cavuoti, S, Cimatti, A, Colodro-Conde, C, Congedo, G, Conselice, CJ, Conversi, L, Copin, Y, Corcione, L, Courbin, F, Courtois, HM, Cropper, M, Da Silva, A, Degaudenzi, H, De Lucia, G, Di Giorgio, AM, Dinis, J, Dubath, F, Duncan, CAJ, Dupac, X, Dusini, S, Farina, M, Farrens, S, Faustini, F, Ferriol, S, Fourmanoit, N, Frailis, M, Franceschi, E, Fumana, M, Galeotta, S, Gillard, W, Gillis, B, Giocoli, C, Granett, BR, Grazian, A, Grupp, F, Guzzo, L, Haugan, SVH, Hoar, J, Hoekstra, H, Holmes, W, Hook, I, Hormuth, F, Hornstrup, A, Hudelot, P, Jahnke, K, Jhabvala, M, Joachimi, B, Keihänen, E, Kermiche, S, Kiessling, A, Kilbinger, M, Kohley, R, Kubik, B, Kümmel, M, Kunz, M, Kurki-Suonio, H, Lahav, O, Laureijs, R, Le Mignant, D, Ligori, S, Lilje, PB, Lindholm, V, Lloro, I, Mainetti, G, Maiorano, E, Mansutti, O, Marggraf, O, Markovic, K, Martinelli, M, Martinet, N, Marulli, F, Massey, R, Medinaceli, E, Mei, S, Melchior, M, Mellier, Y, Merlin, E, Meylan, G, Moresco, M, Moscardini, L, Nakajima, R, Nichol, RC, Niemi, SM, Nightingale, JW, Padilla, C, Paltani, S, Pasian, F, Pedersen, K, Percival, WJ, Pettorino, V, Pires, S, Polenta, G, Poncet, M, Popa, LA, Pozzetti, L, Raison, F, Rebolo, R, Renzi, A, Rhodes, J, Riccio, G, Rix, HW, Romelli, E, Roncarelli, M, Rossetti, E, Rusholme, B, Saglia, R, Sakr, Z, Sánchez, AG, Sapone, D, Sartoris, B, Schneider, P, Schrabback, T, Secroun, A, Seidel, G, Serrano, S, Sirignano, C, Sirri, G, Stanco, L, Steinwagner, J, Tallada-Crespí, P, Tereno, I, Toledo-Moreo, R, Torradeflot, F, Tutusaus, I, Valenziano, L, Vassallo, T, Verdoes Kleijn, G, Veropalumbo, A, Wang, Y, Weller, J, Zacchei, A, Zamorani, G, Zucca, E, Burigana, C, Casenove, P, Mora, A, Scottez, V, Viel, M, Jauzac, M & Dannerbauer, H 2025, 'Euclid: A complete Einstein ring in NGC 6505', Astronomy and Astrophysics, vol. 694, A145. https://doi.org/10.1051/0004-6361/202453014

TY - JOUR

T1 - Euclid: A complete Einstein ring in NGC 6505

AU - O'Riordan, C. M.

AU - Oldham, L. J.

AU - Nersesian, A.

AU - Li, T.

AU - Collett, T. E.

AU - Sluse, D.

AU - Altieri, B.

AU - Clément, B.

AU - Vasan, K. G.C.

AU - Rhoades, S.

AU - Chen, Y.

AU - Jones, T.

AU - Adami, C.

AU - Gavazzi, R.

AU - Vegetti, S.

AU - Powell, D. M.

AU - Acevedo Barroso, J. A.

AU - Andika, I. T.

AU - Bhatawdekar, R.

AU - Cooray, A. R.

AU - Despali, G.

AU - Diego, J. M.

AU - Ecker, L. R.

AU - Galan, A.

AU - Gómez-Alvarez, P.

AU - Leuzzi, L.

AU - Meneghetti, M.

AU - Metcalf, R. B.

AU - Schirmer, M.

AU - Serjeant, S.

AU - Tortora, C.

AU - Vaccari, M.

AU - Vernardos, G.

AU - Walmsley, M.

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 - Basset, A.

AU - Battaglia, P.

AU - Bender, R.

AU - Bonino, D.

AU - Branchini, E.

AU - Brescia, M.

AU - Brinchmann, J.

AU - Caillat, A.

AU - Camera, S.

AU - Capobianco, V.

AU - Carbone, C.

AU - Carretero, J.

AU - Casas, S.

AU - Castander, F. J.

AU - Castellano, M.

AU - Castignani, G.

AU - Cavuoti, S.

AU - Cimatti, A.

AU - Colodro-Conde, C.

AU - Congedo, G.

AU - Conselice, C. J.

AU - Conversi, L.

AU - Copin, Y.

AU - Corcione, L.

AU - Courbin, F.

AU - Courtois, H. M.

AU - Cropper, M.

AU - Da Silva, A.

AU - Degaudenzi, H.

AU - De Lucia, G.

AU - Di Giorgio, A. M.

AU - Dinis, J.

AU - Dubath, F.

AU - Duncan, C. A.J.

AU - Dupac, X.

AU - Dusini, S.

AU - Farina, M.

AU - Farrens, S.

AU - Faustini, F.

AU - Ferriol, S.

AU - Fourmanoit, N.

AU - Frailis, M.

AU - Franceschi, E.

AU - Fumana, M.

AU - Galeotta, S.

AU - Gillard, W.

AU - Gillis, B.

AU - Giocoli, C.

AU - Granett, B. R.

AU - Grazian, A.

AU - Grupp, F.

AU - Guzzo, L.

AU - Haugan, S. V.H.

AU - Hoar, J.

AU - Hoekstra, H.

AU - Holmes, W.

AU - Hook, I.

AU - Hormuth, F.

AU - Hornstrup, A.

AU - Hudelot, P.

AU - Jahnke, K.

AU - Jhabvala, M.

AU - Joachimi, B.

AU - Keihänen, E.

AU - Kermiche, S.

AU - Kiessling, A.

AU - Kilbinger, M.

AU - Kohley, R.

AU - Kubik, B.

AU - Kümmel, M.

AU - Kunz, M.

AU - Kurki-Suonio, H.

AU - Lahav, O.

AU - Laureijs, R.

AU - Le Mignant, D.

AU - Ligori, S.

AU - Lilje, P. B.

AU - Lindholm, V.

AU - Lloro, I.

AU - Mainetti, G.

AU - Maiorano, E.

AU - Mansutti, O.

AU - Marggraf, O.

AU - Markovic, K.

AU - Martinelli, M.

AU - Martinet, N.

AU - Marulli, F.

AU - Massey, R.

AU - Medinaceli, E.

AU - Mei, S.

AU - Melchior, M.

AU - Mellier, Y.

AU - Merlin, E.

AU - Meylan, G.

AU - Moresco, M.

AU - Moscardini, L.

AU - Nakajima, R.

AU - Nichol, R. C.

AU - Niemi, S. M.

AU - Nightingale, J. W.

AU - Padilla, C.

AU - Paltani, S.

AU - Pasian, F.

AU - Pedersen, K.

AU - Percival, W. J.

AU - Pettorino, V.

AU - Pires, S.

AU - Polenta, G.

AU - Poncet, M.

AU - Popa, L. A.

AU - Pozzetti, L.

AU - Raison, F.

AU - Rebolo, R.

AU - Renzi, A.

AU - Rhodes, J.

AU - Riccio, G.

AU - Rix, H. W.

AU - Romelli, E.

AU - Roncarelli, M.

AU - Rossetti, E.

AU - Rusholme, B.

AU - Saglia, R.

AU - Sakr, Z.

AU - Sánchez, A. G.

AU - Sapone, D.

AU - Sartoris, B.

AU - Schneider, P.

AU - Schrabback, T.

AU - Secroun, A.

AU - Seidel, G.

AU - Serrano, S.

AU - Sirignano, C.

AU - Sirri, G.

AU - Stanco, L.

AU - Steinwagner, J.

AU - Tallada-Crespí, P.

AU - Tereno, I.

AU - Toledo-Moreo, R.

AU - Torradeflot, F.

AU - Tutusaus, I.

AU - Valenziano, L.

AU - Vassallo, T.

AU - Verdoes Kleijn, G.

AU - Veropalumbo, A.

AU - Wang, Y.

AU - Weller, J.

AU - Zacchei, A.

AU - Zamorani, G.

AU - Zucca, E.

AU - Burigana, C.

AU - Casenove, P.

AU - Mora, A.

AU - Scottez, V.

AU - Viel, M.

AU - Jauzac, M.

AU - Dannerbauer, H.

PY - 2025

Y1 - 2025

N2 - We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (IE = 18.1 lensed, IE = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by Euclid. We present deep imaging data of the lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the Keck Cosmic Web Imager (KCWI). The Euclid imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of z = 0.406. Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of σ∗ = 303 ± 15 km s-1. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of 2.″5, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, Reff ∼ 12.″3. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of fDM = (11.1-3.5+5.4)% and a stellar initial mass-function (IMF) mismatch parameter of αIMF = 1.26-0.08+0.05, indicating a heavier-than-Chabrier IMF in the centre of the galaxy.

AB - We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (IE = 18.1 lensed, IE = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by Euclid. We present deep imaging data of the lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the Keck Cosmic Web Imager (KCWI). The Euclid imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of z = 0.406. Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of σ∗ = 303 ± 15 km s-1. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of 2.″5, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, Reff ∼ 12.″3. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of fDM = (11.1-3.5+5.4)% and a stellar initial mass-function (IMF) mismatch parameter of αIMF = 1.26-0.08+0.05, indicating a heavier-than-Chabrier IMF in the centre of the galaxy.

KW - Galaxies: individual: NGC 6505

KW - Gravitational lensing: strong

KW - Surveys

U2 - 10.1051/0004-6361/202453014

DO - 10.1051/0004-6361/202453014

M3 - Journal article

AN - SCOPUS:85218115642

SN - 0004-6361

VL - 694

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A145

ER -

Euclid: A complete Einstein ring in NGC 6505

Abstract

Keywords

Access to Document

OpenUrl availability

Fingerprint

Cite this