2025A&A...694A.145O

Query : 2025A&A...694A.145O

2025A&A...694A.145O - Astronomy and Astrophysics, volume 694A145 (2025/2-1)

Euclid: A complete Einstein ring in NGC 6505.

O'RIORDAN C.M., OLDHAM L.J., NERSESIAN A., LI T., COLLETT T.E., SLUSE D., ALTIERI B., CLEMENT 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., COORAY A.R., DESPALI G., DIEGO J.M., ECKER L.R., GALAN A., GOMEZ-ALVAREZ P., LEUZZI L., MENEGHETTI M., METCALF R.B., 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 F.J., CASTELLANO M., CASTIGNANI G., CAVUOTI S., CIMATTI A., COLODRO-CONDE C., CONGEDO G., CONSELICE C.J., CONVERSI L., COPIN Y., CORCIONE L., COURBIN F., COURTOIS H.M., CROPPER M., DA SILVA A., DEGAUDENZI H., DE LUCIA G., DI GIORGIO A.M., DINIS J., DUBATH F., DUNCAN C.A.J., 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 B.R., GRAZIAN A., GRUPP F., GUZZO L., HAUGAN S.V.H., HOAR J., HOEKSTRA H., HOLMES W., HOOK I., HORMUTH F., HORNSTRUP A., HUDELOT P., JAHNKE K., JHABVALA M., JOACHIMI B., KEIHANEN E., KERMICHE S., KIESSLING A., KILBINGER M., KOHLEY R., KUBIK B., KUMMEL M., KUNZ M., KURKI-SUONIO H., LAHAV O., LAUREIJS R., LE MIGNANT D., LIGORI S., LILJE P.B., 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 R.C., NIEMI S.-M., NIGHTINGALE J.W., PADILLA C., PALTANI S., PASIAN F., PEDERSEN K., PERCIVAL W.J., PETTORINO V., PIRES S., POLENTA G., PONCET M., POPA L.A., POZZETTI L., RAISON F., REBOLO R., RENZI A., RHODES J., RICCIO G., RIX H.-W., ROMELLI E., RONCARELLI M., ROSSETTI E., RUSHOLME B., SAGLIA R., SAKR Z., SANCHEZ A.G., SAPONE D., SARTORIS B., SCHNEIDER P., SCHRABBACK T., SECROUN A., SEIDEL G., SERRANO S., SIRIGNANO C., SIRRI G., STANCO L., STEINWAGNER J., TALLADA-CRESPI 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. and DANNERBAUER H.

Abstract (from CDS):

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{{{\overset{\prime\prime}{.}}}}5 $, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, $ R_{\mathrm{eff}}\sim 12{{{\overset{\prime\prime}{.}}}}3 $. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of $ {f_{\mathrm{DM}}} = (11.1_{-3.5}^{+5.4})\% $ and a stellar initial mass-function (IMF) mismatch parameter of $ {\alpha_{\mathrm{IMF}}} = 1.26_{-0.08}^{+0.05} $, indicating a heavier-than-Chabrier IMF in the centre of the galaxy.

Abstract Copyright: © The Authors 2025

Journal keyword(s): gravitational lensing: strong - surveys - galaxies: individual: NGC 6505

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 LEDA 1016399 G 01 41 42.3185073600 -07 35 28.540160448   15.23   13.79   ~ 17 0
2 LEDA 3092574 G 04 03 50.249 -02 39 27.54   16.54   15.08   ~ 19 0
3 MCG-06-30-020 BiC 13 43 33.2178202056 -38 10 33.460160808   13.89   12.47 12.66 ~ 57 2
4 NGC 6505 GiG 17 51 07.405 +65 31 50.80   15.4       ~ 18 0
5 ESO 286-22 GiG 21 00 28.6805291280 -42 25 23.539053180   15.01   13.91   ~ 25 0
6 Z 378-15 AGN 22 40 30.23447 +03 21 30.6290           ~ 636 0

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