Euclid Early Release Observations -- Deep anatomy of nearby galaxies

Euclid Collaboration; L. K. Hunt; F. Annibali; J. -C. Cuillandre; A. M. N. Ferguson; P. Jablonka; S. S. Larsen; F. R. Marleau; E. Schinnerer; M. Schirmer; C. Stone; C. Tortora; T. Saifollahi; A. Lançon; M. Bolzonella; S. Gwyn; M. Kluge; R. Laureijs; D. Carollo; M. L. M. Collins; P. Dimauro; P. -A. Duc; D. Erkal; J. M. Howell; C. Nally; E. Saremi; R. Scaramella; V. Belokurov; C. J. Conselice; J. H. Knapen; A. W. McConnachie; I. McDonald; J. Miro Carretero; J. Roman; M. Sauvage; E. Sola; N. Aghanim; B. Altieri; S. Andreon; N. Auricchio; S. Awan; R. Azzollini; M. Baldi; A. Balestra; S. Bardelli; A. Basset; R. Bender; D. Bonino; E. Branchini; M. Brescia; J. Brinchmann; S. Camera; G. P. Candini; V. Capobianco; C. Carbone; J. Carretero; S. Casas; M. Castellano; S. Cavuoti; A. Cimatti; G. Congedo; L. Conversi; Y. Copin; L. Corcione; F. Courbin; H. M. Courtois; M. Cropper; A. Da Silva; H. Degaudenzi; A. M. Di Giorgio; J. Dinis; F. Dubath; X. Dupac; S. Dusini; M. Farina; S. Farrens; S. Ferriol; P. Fosalba; M. Frailis; E. Franceschi; M. Fumana; S. Galeotta; B. Garilli; W. Gillard; B. Gillis; C. Giocoli; P. Gómez-Alvarez; B. R. Granett; A. Grazian; F. Grupp; L. Guzzo; S. V. H. Haugan; J. Hoar; H. Hoekstra; M. S. Holliman; W. Holmes; I. Hook; F. Hormuth; A. Hornstrup; P. Hudelot; K. Jahnke; E. Keihänen; S. Kermiche; A. Kiessling; M. Kilbinger; T. Kitching; R. Kohley; B. Kubik; K. Kuijken; M. Kümmel; M. Kunz; H. Kurki-Suonio; O. Lahav; D. Le Mignant; P. B. Lilje; V. Lindholm; I. Lloro; E. Maiorano; O. Mansutti; O. Marggraf; K. Markovic; N. Martinet; F. Marulli; R. Massey; S. Maurogordato; H. J. McCracken; E. Medinaceli; S. Mei; Y. Mellier; M. Meneghetti; E. Merlin; G. Meylan; M. Moresco; L. Moscardini; E. Munari; 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; G. D. Racca; F. Raison; R. Rebolo; A. Refregier; A. Renzi; J. Rhodes; G. Riccio; E. Romelli; M. Roncarelli; E. Rossetti; R. Saglia; D. Sapone; B. Sartoris; P. Schneider; T. Schrabback; M. Scodeggio; A. Secroun; G. Seidel; S. Serrano; C. Sirignano; G. Sirri; J. Skottfelt; L. Stanco; P. Tallada-Crespí; D. Tavagnacco; A. N. Taylor; H. I. Teplitz; I. Tereno; R. Toledo-Moreo; F. Torradeflot; I. Tutusaus; E. A. Valentijn; L. Valenziano; T. Vassallo; G. Verdoes Kleijn; A. Veropalumbo; Y. Wang; J. Weller; O. R. Williams; G. Zamorani; E. Zucca; C. Burigana; G. De Lucia; K. George; V. Scottez; M. Miluzio; P. Simon; A. Mora; J. Martín-Fleitas; D. Scott

doi:10.1051/0004-6361/202450781

Euclid Early Release Observations -- Deep anatomy of nearby galaxies

Euclid Collaboration, L. K. Hunt^*, F. Annibali, J. -C. Cuillandre, A. M. N. Ferguson, P. Jablonka, S. S. Larsen, F. R. Marleau, E. Schinnerer, M. Schirmer, C. Stone, C. Tortora, T. Saifollahi, A. Lançon, M. Bolzonella, S. Gwyn, M. Kluge, R. Laureijs, D. Carollo, M. L. M. CollinsP. Dimauro, P. -A. Duc, D. Erkal, J. M. Howell, C. Nally, E. Saremi, R. Scaramella, V. Belokurov, C. J. Conselice, J. H. Knapen, A. W. McConnachie, I. McDonald, J. Miro Carretero, J. Roman, M. Sauvage, E. Sola, N. Aghanim, B. Altieri, S. Andreon, N. Auricchio, S. Awan, R. Azzollini, M. Baldi, A. Balestra, S. Bardelli, A. Basset, R. Bender, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, G. P. Candini, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, S. Cavuoti, A. Cimatti, G. Congedo, L. Conversi, Y. Copin, L. Corcione, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, A. M. Di Giorgio, J. Dinis, F. Dubath, X. Dupac, S. Dusini, M. Farina, S. Farrens, S. Ferriol, P. Fosalba, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, B. Garilli, W. Gillard, B. Gillis, C. Giocoli, P. Gómez-Alvarez, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, J. Hoar, H. Hoekstra, M. S. Holliman, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, T. Kitching, R. Kohley, B. Kubik, K. Kuijken, M. Kümmel, M. Kunz, H. Kurki-Suonio, O. Lahav, D. Le Mignant, P. B. Lilje, V. Lindholm, I. Lloro, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, S. Maurogordato, H. J. McCracken, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, M. Moresco, L. Moscardini, E. Munari, 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, G. D. Racca, F. Raison, R. Rebolo, A. Refregier, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, E. Rossetti, R. Saglia, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, M. Scodeggio, A. Secroun, G. Seidel, S. Serrano, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, P. Tallada-Crespí, D. Tavagnacco, A. N. Taylor, H. I. Teplitz, I. Tereno, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, E. A. Valentijn, L. Valenziano, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, O. R. Williams, G. Zamorani, E. Zucca, C. Burigana, G. De Lucia, K. George, V. Scottez, M. Miluzio, P. Simon, A. Mora, J. Martín-Fleitas, D. Scott

^*Corresponding author for this work

School of Physics and Astronomy

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

Abstract

Euclid is poised to make significant advances in the study of nearby galaxies in the Local Universe. Here we present a first look at six galaxies observed for the Nearby Galaxy Showcase as part of the Euclid Early Release Observations acquired between August and November, 2023. These targets, three dwarf galaxies (Holmberg II, IC 10, and NGC 6822) and three spirals (IC 342, NGC 2403, and NGC 6744), range in distance from about 0.5 Mpc to 8.8 Mpc. We first assess the surface brightness depths in the stacked Euclid images, and confirm previous estimates in 100 arcsec2 regions for Visible Camera (VIS) of 1σ limits of 30.5 mag arcsec-2, but find deeper than previous estimates for Near-Infrared Spectrometer and Photometer (NISP) with 1σ = 29.2-29.4mag arcsec-2. By combining Euclid HE, YE, and IE into RGB images, we illustrate the large field of view (FoV) covered by a single reference observing sequence (ROS), together with exquisite detail on scales of <1-4 parsecs in these nearby galaxies. Our analysis of radial surface brightness and color profiles demonstrates that the photometric calibration of Euclid is consistent with what is expected for galaxy colors according to stellar synthesis models. We perform standard source-selection techniques for stellar photometry, and find approximately 1.3 million stars across the six galaxy fields. After subtracting foreground stars and background galaxies, and applying a color and magnitude selection, we extract stellar populations of different ages for the six galaxies. The resolved stellar photometry obtained with Euclid allows us to constrain the star-formation histories of these galaxies, which we do by disentangling the distributions of young stars and asymptotic giant branch and red giant branch stellar populations. We finally examine two galaxies individually for surrounding systems of dwarf galaxy satellites and globular cluster populations. Our analysis of the ensemble of dwarf satellites around NGC 6744 recovers all the previously known dwarf satellites within the Euclid FoV, and also confirms the satellite nature of a previously identified candidate, dw1909m6341, a nucleated dwarf spheroidal at the end of a spiral arm. Our new census of the globular clusters around NGC 2403 yields nine new star-cluster candidates, eight of which exhibit colors indicative of evolved stellar populations. In summary, our first investigation of six “showcase” galaxies demonstrates that Euclid is a powerful probe of stellar structure and stellar populations in nearby galaxies, and will provide vastly improved statistics on dwarf satellite systems and extragalactic globular clusters in the local Universe, among many other exciting results.

Original language	English
Article number	A9
Pages (from-to)	1-35
Number of pages	35
Journal	Astronomy and Astrophysics
Volume	697
Early online date	30 Apr 2025
DOIs	https://doi.org/10.1051/0004-6361/202450781
Publication status	Published - 1 May 2025

Keywords / Materials (for Non-textual outputs)

Galaxies: dwarf
Galaxies: irregular
Galaxies: spiral
Galaxies: starburst
Galaxies: stellar content

Access to Document

10.1051/0004-6361/202450781Licence: Creative Commons: Attribution (CC-BY)

https://arxiv.org/abs/2405.13499Licence: Creative Commons: Attribution (CC-BY)

The Archaeological Record in Local Galaxy Stellar Halos
Ferguson, A. (Principal Investigator)
Science and Technology Facilities Council
1/04/24 → 31/03/27
Project: Research

Cite this

Euclid Collaboration, Hunt, L. K., Annibali, F., Cuillandre, J. .-C., Ferguson, A. M. N., Jablonka, P., Larsen, S. S., Marleau, F. R., Schinnerer, E., Schirmer, M., Stone, C., Tortora, C., Saifollahi, T., Lançon, A., Bolzonella, M., Gwyn, S., Kluge, M., Laureijs, R., Carollo, D., ... Scott, D. (2025). Euclid Early Release Observations -- Deep anatomy of nearby galaxies. Astronomy and Astrophysics, 697, 1-35. Article A9. https://doi.org/10.1051/0004-6361/202450781

@article{8a86aeee1c5f46feb4e63cee0ecec22e,

title = "Euclid Early Release Observations -- Deep anatomy of nearby galaxies",

abstract = "Euclid is poised to make significant advances in the study of nearby galaxies in the Local Universe. Here we present a first look at six galaxies observed for the Nearby Galaxy Showcase as part of the Euclid Early Release Observations acquired between August and November, 2023. These targets, three dwarf galaxies (Holmberg II, IC 10, and NGC 6822) and three spirals (IC 342, NGC 2403, and NGC 6744), range in distance from about 0.5 Mpc to 8.8 Mpc. We first assess the surface brightness depths in the stacked Euclid images, and confirm previous estimates in 100 arcsec2 regions for Visible Camera (VIS) of 1σ limits of 30.5 mag arcsec-2, but find deeper than previous estimates for Near-Infrared Spectrometer and Photometer (NISP) with 1σ = 29.2-29.4mag arcsec-2. By combining Euclid HE, YE, and IE into RGB images, we illustrate the large field of view (FoV) covered by a single reference observing sequence (ROS), together with exquisite detail on scales of <1-4 parsecs in these nearby galaxies. Our analysis of radial surface brightness and color profiles demonstrates that the photometric calibration of Euclid is consistent with what is expected for galaxy colors according to stellar synthesis models. We perform standard source-selection techniques for stellar photometry, and find approximately 1.3 million stars across the six galaxy fields. After subtracting foreground stars and background galaxies, and applying a color and magnitude selection, we extract stellar populations of different ages for the six galaxies. The resolved stellar photometry obtained with Euclid allows us to constrain the star-formation histories of these galaxies, which we do by disentangling the distributions of young stars and asymptotic giant branch and red giant branch stellar populations. We finally examine two galaxies individually for surrounding systems of dwarf galaxy satellites and globular cluster populations. Our analysis of the ensemble of dwarf satellites around NGC 6744 recovers all the previously known dwarf satellites within the Euclid FoV, and also confirms the satellite nature of a previously identified candidate, dw1909m6341, a nucleated dwarf spheroidal at the end of a spiral arm. Our new census of the globular clusters around NGC 2403 yields nine new star-cluster candidates, eight of which exhibit colors indicative of evolved stellar populations. In summary, our first investigation of six “showcase” galaxies demonstrates that Euclid is a powerful probe of stellar structure and stellar populations in nearby galaxies, and will provide vastly improved statistics on dwarf satellite systems and extragalactic globular clusters in the local Universe, among many other exciting results.",

keywords = "Galaxies: dwarf, Galaxies: irregular, Galaxies: spiral, Galaxies: starburst, Galaxies: stellar content",

author = "{Euclid Collaboration} and Hunt, {L. K.} and F. Annibali and Cuillandre, {J. -C.} and Ferguson, {A. M. N.} and P. Jablonka and Larsen, {S. S.} and Marleau, {F. R.} and E. Schinnerer and M. Schirmer and C. Stone and C. Tortora and T. Saifollahi and A. Lan{\c c}on and M. Bolzonella and S. Gwyn and M. Kluge and R. Laureijs and D. Carollo and Collins, {M. L. M.} and P. Dimauro and Duc, {P. -A.} and D. Erkal and Howell, {J. M.} and C. Nally and E. Saremi and R. Scaramella and V. Belokurov and Conselice, {C. J.} and Knapen, {J. H.} and McConnachie, {A. W.} and I. McDonald and Carretero, {J. Miro} and J. Roman and M. Sauvage and E. Sola and N. Aghanim and B. Altieri and S. Andreon and N. Auricchio and S. Awan and R. Azzollini and M. Baldi and A. Balestra and S. Bardelli and A. Basset and R. Bender and D. Bonino and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and Candini, {G. P.} and V. Capobianco and C. Carbone and J. Carretero and S. Casas and M. Castellano and S. Cavuoti and A. Cimatti and G. Congedo and L. Conversi and Y. Copin and L. Corcione and F. Courbin and Courtois, {H. M.} and M. Cropper and Silva, {A. Da} and H. Degaudenzi and Giorgio, {A. M. Di} and J. Dinis and F. Dubath and X. Dupac and S. Dusini and M. Farina and S. Farrens and S. Ferriol and P. Fosalba and M. Frailis and E. Franceschi and M. Fumana and S. Galeotta and B. Garilli and W. Gillard and B. Gillis and C. Giocoli and P. G{\'o}mez-Alvarez 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 Holliman, {M. S.} and W. Holmes and I. Hook and F. Hormuth and A. Hornstrup and P. Hudelot and K. Jahnke and E. Keih{\"a}nen and S. Kermiche and A. Kiessling and M. Kilbinger and T. Kitching and R. Kohley and B. Kubik and K. Kuijken and M. K{\"u}mmel and M. Kunz and H. Kurki-Suonio and O. Lahav and Mignant, {D. Le} and Lilje, {P. B.} and V. Lindholm and I. Lloro and E. Maiorano and O. Mansutti and O. Marggraf and K. Markovic and N. Martinet and F. Marulli and R. Massey and S. Maurogordato and McCracken, {H. J.} and E. Medinaceli and S. Mei and Y. Mellier and M. Meneghetti and E. Merlin and G. Meylan and M. Moresco and L. Moscardini and E. Munari 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 Racca, {G. D.} and F. Raison and R. Rebolo and A. Refregier and A. Renzi and J. Rhodes and G. Riccio and E. Romelli and M. Roncarelli and E. Rossetti and R. Saglia and D. Sapone and B. Sartoris and P. Schneider and T. Schrabback and M. Scodeggio and A. Secroun and G. Seidel and S. Serrano and C. Sirignano and G. Sirri and J. Skottfelt and L. Stanco and P. Tallada-Cresp{\'i} and D. Tavagnacco and Taylor, {A. N.} and Teplitz, {H. I.} and I. Tereno and R. Toledo-Moreo and F. Torradeflot and I. Tutusaus and Valentijn, {E. A.} and L. Valenziano and T. Vassallo and Kleijn, {G. Verdoes} and A. Veropalumbo and Y. Wang and J. Weller and Williams, {O. R.} and G. Zamorani and E. Zucca and C. Burigana and Lucia, {G. De} and K. George and V. Scottez and M. Miluzio and P. Simon and A. Mora and J. Mart{\'i}n-Fleitas and D. Scott",

note = "36 pages; 20 figures in main text; 4 Appendices. Submitted to A&A, as part of the A&A special issue `Euclid on Sky', which contains Euclid key reference papers and first results from the Euclid Early Release Observations",

year = "2025",

month = may,

day = "1",

doi = "10.1051/0004-6361/202450781",

language = "English",

volume = "697",

pages = "1--35",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Euclid Collaboration, Hunt, LK, Annibali, F, Cuillandre, J-C, Ferguson, AMN, Jablonka, P, Larsen, SS, Marleau, FR, Schinnerer, E, Schirmer, M, Stone, C, Tortora, C, Saifollahi, T, Lançon, A, Bolzonella, M, Gwyn, S, Kluge, M, Laureijs, R, Carollo, D, Collins, MLM, Dimauro, P, Duc, P-A, Erkal, D, Howell, JM, Nally, C, Saremi, E, Scaramella, R, Belokurov, V, Conselice, CJ, Knapen, JH, McConnachie, AW, McDonald, I, Carretero, JM, Roman, J, Sauvage, M, Sola, E, Aghanim, N, Altieri, B, Andreon, S, Auricchio, N, Awan, S, Azzollini, R, Baldi, M, Balestra, A, Bardelli, S, Basset, A, Bender, R, Bonino, D, Branchini, E, Brescia, M, Brinchmann, J, Camera, S, Candini, GP, Capobianco, V, Carbone, C, Carretero, J, Casas, S, Castellano, M, Cavuoti, S, Cimatti, A, Congedo, G, Conversi, L, Copin, Y, Corcione, L, Courbin, F, Courtois, HM, Cropper, M, Silva, AD, Degaudenzi, H, Giorgio, AMD, Dinis, J, Dubath, F, Dupac, X, Dusini, S, Farina, M, Farrens, S, Ferriol, S, Fosalba, P, Frailis, M, Franceschi, E, Fumana, M, Galeotta, S, Garilli, B, Gillard, W, Gillis, B, Giocoli, C, Gómez-Alvarez, P, Granett, BR, Grazian, A, Grupp, F, Guzzo, L, Haugan, SVH, Hoar, J, Hoekstra, H, Holliman, MS, Holmes, W, Hook, I, Hormuth, F, Hornstrup, A, Hudelot, P, Jahnke, K, Keihänen, E, Kermiche, S, Kiessling, A, Kilbinger, M, Kitching, T, Kohley, R, Kubik, B, Kuijken, K, Kümmel, M, Kunz, M, Kurki-Suonio, H, Lahav, O, Mignant, DL, Lilje, PB, Lindholm, V, Lloro, I, Maiorano, E, Mansutti, O, Marggraf, O, Markovic, K, Martinet, N, Marulli, F, Massey, R, Maurogordato, S, McCracken, HJ, Medinaceli, E, Mei, S, Mellier, Y, Meneghetti, M, Merlin, E, Meylan, G, Moresco, M, Moscardini, L, Munari, E, Nakajima, R, Nichol, RC, Niemi, S-M, Nightingale, JW, Padilla, C, Paltani, S, Pasian, F, Pedersen, K, Percival, WJ, Pettorino, V, Pires, S, Polenta, G, Poncet, M, Popa, LA, Pozzetti, L, Racca, GD, Raison, F, Rebolo, R, Refregier, A, Renzi, A, Rhodes, J, Riccio, G, Romelli, E, Roncarelli, M, Rossetti, E, Saglia, R, Sapone, D, Sartoris, B, Schneider, P, Schrabback, T, Scodeggio, M, Secroun, A, Seidel, G, Serrano, S, Sirignano, C, Sirri, G, Skottfelt, J, Stanco, L, Tallada-Crespí, P, Tavagnacco, D, Taylor, AN, Teplitz, HI, Tereno, I, Toledo-Moreo, R, Torradeflot, F, Tutusaus, I, Valentijn, EA, Valenziano, L, Vassallo, T, Kleijn, GV, Veropalumbo, A, Wang, Y, Weller, J, Williams, OR, Zamorani, G, Zucca, E, Burigana, C, Lucia, GD, George, K, Scottez, V, Miluzio, M, Simon, P, Mora, A, Martín-Fleitas, J & Scott, D 2025, 'Euclid Early Release Observations -- Deep anatomy of nearby galaxies', Astronomy and Astrophysics, vol. 697, A9, pp. 1-35. https://doi.org/10.1051/0004-6361/202450781

TY - JOUR

T1 - Euclid Early Release Observations -- Deep anatomy of nearby galaxies

AU - Euclid Collaboration

AU - Hunt, L. K.

AU - Annibali, F.

AU - Cuillandre, J. -C.

AU - Ferguson, A. M. N.

AU - Jablonka, P.

AU - Larsen, S. S.

AU - Marleau, F. R.

AU - Schinnerer, E.

AU - Schirmer, M.

AU - Stone, C.

AU - Tortora, C.

AU - Saifollahi, T.

AU - Lançon, A.

AU - Bolzonella, M.

AU - Gwyn, S.

AU - Kluge, M.

AU - Laureijs, R.

AU - Carollo, D.

AU - Collins, M. L. M.

AU - Dimauro, P.

AU - Duc, P. -A.

AU - Erkal, D.

AU - Howell, J. M.

AU - Nally, C.

AU - Saremi, E.

AU - Scaramella, R.

AU - Belokurov, V.

AU - Conselice, C. J.

AU - Knapen, J. H.

AU - McConnachie, A. W.

AU - McDonald, I.

AU - Carretero, J. Miro

AU - Roman, J.

AU - Sauvage, M.

AU - Sola, E.

AU - Aghanim, N.

AU - Altieri, B.

AU - Andreon, S.

AU - Auricchio, N.

AU - Awan, S.

AU - Azzollini, R.

AU - Baldi, M.

AU - Balestra, A.

AU - Bardelli, S.

AU - Basset, A.

AU - Bender, R.

AU - Bonino, D.

AU - Branchini, E.

AU - Brescia, M.

AU - Brinchmann, J.

AU - Camera, S.

AU - Candini, G. P.

AU - Capobianco, V.

AU - Carbone, C.

AU - Carretero, J.

AU - Casas, S.

AU - Castellano, M.

AU - Cavuoti, S.

AU - Cimatti, A.

AU - Congedo, G.

AU - Conversi, L.

AU - Copin, Y.

AU - Corcione, L.

AU - Courbin, F.

AU - Courtois, H. M.

AU - Cropper, M.

AU - Silva, A. Da

AU - Degaudenzi, H.

AU - Giorgio, A. M. Di

AU - Dinis, J.

AU - Dubath, F.

AU - Dupac, X.

AU - Dusini, S.

AU - Farina, M.

AU - Farrens, S.

AU - Ferriol, S.

AU - Fosalba, P.

AU - Frailis, M.

AU - Franceschi, E.

AU - Fumana, M.

AU - Galeotta, S.

AU - Garilli, B.

AU - Gillard, W.

AU - Gillis, B.

AU - Giocoli, C.

AU - Gómez-Alvarez, P.

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 - Holliman, M. S.

AU - Holmes, W.

AU - Hook, I.

AU - Hormuth, F.

AU - Hornstrup, A.

AU - Hudelot, P.

AU - Jahnke, K.

AU - Keihänen, E.

AU - Kermiche, S.

AU - Kiessling, A.

AU - Kilbinger, M.

AU - Kitching, T.

AU - Kohley, R.

AU - Kubik, B.

AU - Kuijken, K.

AU - Kümmel, M.

AU - Kunz, M.

AU - Kurki-Suonio, H.

AU - Lahav, O.

AU - Mignant, D. Le

AU - Lilje, P. B.

AU - Lindholm, V.

AU - Lloro, I.

AU - Maiorano, E.

AU - Mansutti, O.

AU - Marggraf, O.

AU - Markovic, K.

AU - Martinet, N.

AU - Marulli, F.

AU - Massey, R.

AU - Maurogordato, S.

AU - McCracken, H. J.

AU - Medinaceli, E.

AU - Mei, S.

AU - Mellier, Y.

AU - Meneghetti, M.

AU - Merlin, E.

AU - Meylan, G.

AU - Moresco, M.

AU - Moscardini, L.

AU - Munari, E.

AU - Nakajima, R.

AU - Nichol, R. C.

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N1 - 36 pages; 20 figures in main text; 4 Appendices. Submitted to A&A, as part of the A&A special issue `Euclid on Sky', which contains Euclid key reference papers and first results from the Euclid Early Release Observations

PY - 2025/5/1

Y1 - 2025/5/1

N2 - Euclid is poised to make significant advances in the study of nearby galaxies in the Local Universe. Here we present a first look at six galaxies observed for the Nearby Galaxy Showcase as part of the Euclid Early Release Observations acquired between August and November, 2023. These targets, three dwarf galaxies (Holmberg II, IC 10, and NGC 6822) and three spirals (IC 342, NGC 2403, and NGC 6744), range in distance from about 0.5 Mpc to 8.8 Mpc. We first assess the surface brightness depths in the stacked Euclid images, and confirm previous estimates in 100 arcsec2 regions for Visible Camera (VIS) of 1σ limits of 30.5 mag arcsec-2, but find deeper than previous estimates for Near-Infrared Spectrometer and Photometer (NISP) with 1σ = 29.2-29.4mag arcsec-2. By combining Euclid HE, YE, and IE into RGB images, we illustrate the large field of view (FoV) covered by a single reference observing sequence (ROS), together with exquisite detail on scales of <1-4 parsecs in these nearby galaxies. Our analysis of radial surface brightness and color profiles demonstrates that the photometric calibration of Euclid is consistent with what is expected for galaxy colors according to stellar synthesis models. We perform standard source-selection techniques for stellar photometry, and find approximately 1.3 million stars across the six galaxy fields. After subtracting foreground stars and background galaxies, and applying a color and magnitude selection, we extract stellar populations of different ages for the six galaxies. The resolved stellar photometry obtained with Euclid allows us to constrain the star-formation histories of these galaxies, which we do by disentangling the distributions of young stars and asymptotic giant branch and red giant branch stellar populations. We finally examine two galaxies individually for surrounding systems of dwarf galaxy satellites and globular cluster populations. Our analysis of the ensemble of dwarf satellites around NGC 6744 recovers all the previously known dwarf satellites within the Euclid FoV, and also confirms the satellite nature of a previously identified candidate, dw1909m6341, a nucleated dwarf spheroidal at the end of a spiral arm. Our new census of the globular clusters around NGC 2403 yields nine new star-cluster candidates, eight of which exhibit colors indicative of evolved stellar populations. In summary, our first investigation of six “showcase” galaxies demonstrates that Euclid is a powerful probe of stellar structure and stellar populations in nearby galaxies, and will provide vastly improved statistics on dwarf satellite systems and extragalactic globular clusters in the local Universe, among many other exciting results.

AB - Euclid is poised to make significant advances in the study of nearby galaxies in the Local Universe. Here we present a first look at six galaxies observed for the Nearby Galaxy Showcase as part of the Euclid Early Release Observations acquired between August and November, 2023. These targets, three dwarf galaxies (Holmberg II, IC 10, and NGC 6822) and three spirals (IC 342, NGC 2403, and NGC 6744), range in distance from about 0.5 Mpc to 8.8 Mpc. We first assess the surface brightness depths in the stacked Euclid images, and confirm previous estimates in 100 arcsec2 regions for Visible Camera (VIS) of 1σ limits of 30.5 mag arcsec-2, but find deeper than previous estimates for Near-Infrared Spectrometer and Photometer (NISP) with 1σ = 29.2-29.4mag arcsec-2. By combining Euclid HE, YE, and IE into RGB images, we illustrate the large field of view (FoV) covered by a single reference observing sequence (ROS), together with exquisite detail on scales of <1-4 parsecs in these nearby galaxies. Our analysis of radial surface brightness and color profiles demonstrates that the photometric calibration of Euclid is consistent with what is expected for galaxy colors according to stellar synthesis models. We perform standard source-selection techniques for stellar photometry, and find approximately 1.3 million stars across the six galaxy fields. After subtracting foreground stars and background galaxies, and applying a color and magnitude selection, we extract stellar populations of different ages for the six galaxies. The resolved stellar photometry obtained with Euclid allows us to constrain the star-formation histories of these galaxies, which we do by disentangling the distributions of young stars and asymptotic giant branch and red giant branch stellar populations. We finally examine two galaxies individually for surrounding systems of dwarf galaxy satellites and globular cluster populations. Our analysis of the ensemble of dwarf satellites around NGC 6744 recovers all the previously known dwarf satellites within the Euclid FoV, and also confirms the satellite nature of a previously identified candidate, dw1909m6341, a nucleated dwarf spheroidal at the end of a spiral arm. Our new census of the globular clusters around NGC 2403 yields nine new star-cluster candidates, eight of which exhibit colors indicative of evolved stellar populations. In summary, our first investigation of six “showcase” galaxies demonstrates that Euclid is a powerful probe of stellar structure and stellar populations in nearby galaxies, and will provide vastly improved statistics on dwarf satellite systems and extragalactic globular clusters in the local Universe, among many other exciting results.

KW - Galaxies: dwarf

KW - Galaxies: irregular

KW - Galaxies: spiral

KW - Galaxies: starburst

KW - Galaxies: stellar content

U2 - 10.1051/0004-6361/202450781

DO - 10.1051/0004-6361/202450781

M3 - Article

SN - 0004-6361

VL - 697

SP - 1

EP - 35

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A9

ER -

Euclid Early Release Observations -- Deep anatomy of nearby galaxies

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