Euclid: Galaxy morphology and photometry from bulge-disc decomposition of Early Release Observations

The background galaxies in Euclid Early Release Observations images of the Perseus cluster make up a remarkable sample in its combination of 0.57 deg$^2$ area, 25.3 and 23.2 AB mag depth, as well as 0.1" and 0.3" angular resolutions, in optical and near-IR bands, respectively. Towards characterising the history of the Hubble sequence, we perform a morphological analysis of 2445 and 12,786 galaxies with $I_E < 21$ and $I_E < 23$, respectively. We use single-Sérsic profiles and the sums of a Sérsic bulge and an exponential disc to model these galaxies with SourceXtractor++ and analyse their parameters in order to assess their consistencies and discrepancies. The fitted galaxies to $I_E < 21$ span the various Hubble types with ubiquitous bulge and disc components, and a bulge-to-total light ratio B/T taking all values from 0 to 1. The effective radius of the single-Sérsic profile is an intermediate estimate of galaxy size, between the bulge and disc effective radii, depending on B/T. The axis ratio of the single-Sérsic profile is higher than the disc axis ratio, increasingly so with B/T. The model impacts the photometry with -0.08 to 0.01 mag median systematic $I_E$ offsets between single-Sérsic and bulge+disc total magnitudes, and a 0.05 to 0.15 mag dispersion, from low to high B/T. We measure a median 0.3 mag bulge-disk colour difference in rest-frame $M_g - M_i$ that originates from the disc-dominated galaxies, whereas bulge-dominated galaxies have similar median colours of their components. Remarkably, we also measure redder-inside disc colour gradients, based on 5 to 10% systematic variations of disc effective radii between the optical and near-IR bands. This analysis demonstrates the usefulness and limitations of single-Sérsic profile modelling, and the power of bulge-disc decomposition for reliably characterising the morphology of lenticulars and spirals in Euclid images.

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ArXiv.org
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2025-02-21
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Astronomy and Astrophysical Research
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Euclid: Galaxy morphology and photometry from bulge-disc decomposition of Early Release Observations

S. Farrens, M. Martinelli, Will J. Percival, F. Pasian et al.
ArXiv.org
Astronomy and Astrophysical Research
article

Euclid: Galaxy morphology and photometry from bulge-disc decomposition of Early Release Observations

S. Farrens, M. Martinelli, Will J. Percival, F. Pasian, D. Le Mignant, M. Brescia, N. Martinet, I Tereno, G de Lucia, D Sapone, M. Bolzonella, M Kümmel, C. Giocoli, E Rossetti, K George, Carmencita David Padilla, Y. Copin, Maureen Cropper, S. Bardelli, F Faustini, Philipp Schneider, Alberto Basset, G Castignani, A.M Di Giorgio, K Jahnke, T. Schrabback, T. Saifollahi, P Gómez-Álvarez, B Altieri, S. Cavuoti, A. Kiessling, S. V. H. Haugan, T. Vassallo, S. Dusini, R. Laureijs, R. Toledo-Moreo, J. Hoar, M. Moresco, G Seidel, M. Baes, L Moscardini, L Stanco, C. Colodro-Conde, F Grupp, N Auricchio, J. Carretero, A. Caillat, F.R Marleau, B Gillis, E. Romelli, Christopher J. Conselice, I. Tutusaus, O. Mansutti, B Sartoris, F. Marulli, R Saglia, P. Tallada-Crespí, J. Väliviita, A. Bonchi, G. Mainetti, N. R. Napolitano, J Brinchmann, K. Pedersen, E. Maiorano, C Baccigalupi, S Casas, Jenny G. Sorce, A. Hornstrup, E Sefusatti, C. Tortora, M. Giulietti, I Damjanov, D Scott, E. Medinaceli, A. Balestra, F. Hormuth, M. Farina, S. Camera, M Jhabvala, R. Nakajima, H Kurki-Suonio, M. Castellano, M Fumana, Angelos Nersesian, G Zamorani, A. Zacchei, Shuqi Mei, S. Galeotta, J. Weller, A Amara, E. Franceschi, L Quilley, Yang Wang, Konrad H. Kuijken, I Lloro, M. Schirmer, V Capobianco, K. Markovič, A Secroun, Z. Sakr, M. Kilbinger, D. Bonino, V. Lindholm, R. Rébolo, G. Verdoes Kleijn, S. Pires, E. Keihänen, E Branchini, A da Silva, M. Melchior, M. Frailis, Jean‐Charles Cuillandre, P. Bergamini, V. de Lapparent, R Massey, E Zucca, P. Hudelot, Gary E. Riccio, S. Kermiche, M Baldi, G Sirri, F Dubath, P. B. Lilje, G Meylan, A Veropalumbo, O Marggraf, P Battaglia, C. Burigana, J. Dinis, L. Pozzetti, R. C. Nichol, S Andreon, M Urbano, M Kunz, F Torradeflot, A. Cimatti, Y. Mellier, S. Paltani, S Serrano, L. Popa, V. Pettorino, A Renzi, G Congedo, E. Merlin, G Polenta, H. Degaudenzi, A. Ealet, A.N Taylor, N. Aghanim, X. Dupac, L Conversi, D Maino, M. Poncet, Jason Rhodes, B. Kubik, M. D. Seiffert, H.M Courtois, S. Fotopoulou, A Mora, L Valenziano, W. N. Holmes, Boris Häußler, C Neissner, A Biviano, S.-M Niemi, F Raison, S. Ferriol, S Ligori, C.A.J Duncan
article en

Abstract

The background galaxies in Euclid Early Release Observations images of the Perseus cluster make up a remarkable sample in its combination of 0.57 deg$^2$ area, 25.3 and 23.2 AB mag depth, as well as 0.1" and 0.3" angular resolutions, in optical and near-IR bands, respectively. Towards characterising the history of the Hubble sequence, we perform a morphological analysis of 2445 and 12,786 galaxies with $I_E < 21$ and $I_E < 23$, respectively. We use single-Sérsic profiles and the sums of a Sérsic bulge and an exponential disc to model these galaxies with SourceXtractor++ and analyse their parameters in order to assess their consistencies and discrepancies. The fitted galaxies to $I_E < 21$ span the various Hubble types with ubiquitous bulge and disc components, and a bulge-to-total light ratio B/T taking all values from 0 to 1. The effective radius of the single-Sérsic profile is an intermediate estimate of galaxy size, between the bulge and disc effective radii, depending on B/T. The axis ratio of the single-Sérsic profile is higher than the disc axis ratio, increasingly so with B/T. The model impacts the photometry with -0.08 to 0.01 mag median systematic $I_E$ offsets between single-Sérsic and bulge+disc total magnitudes, and a 0.05 to 0.15 mag dispersion, from low to high B/T. We measure a median 0.3 mag bulge-disk colour difference in rest-frame $M_g - M_i$ that originates from the disc-dominated galaxies, whereas bulge-dominated galaxies have similar median colours of their components. Remarkably, we also measure redder-inside disc colour gradients, based on 5 to 10% systematic variations of disc effective radii between the optical and near-IR bands. This analysis demonstrates the usefulness and limitations of single-Sérsic profile modelling, and the power of bulge-disc decomposition for reliably characterising the morphology of lenticulars and spirals in Euclid images.

ArXiv.org
Université Paris Cité (FR), Université de Lille (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Centre National d'Études Spatiales (FR), Institut d'Astrophysique de Paris (FR), European Space Agency (FR), Laboratoire AstroParticule et Cosmologie (FR), Observatoire astronomique de Strasbourg (FR), Astrophysique, Instrumentation et Modélisation (FR), Centre de Recherche Astrophysique de Lyon (FR), Centre de physique des particules de Marseille (FR), Laboratoire d’Astrophysique de Marseille (FR), Institut d'Astrophysique Spatiale (FR), Château Gombert (FR), CEA Paris-Saclay (FR), Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules (FR), Institute of Nuclear Physics of Lyon (FR), Institut de Recherche en Astrophysique et Planétologie (FR), Institut de Physique des 2 Infinis de Lyon (FR)
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