J/A+A/711/A10 Euclid (Q1). Census of dwarf galaxies (Euclid Coll., 2026)
Euclid: Quick Data Release (Q1). A census of dwarf galaxies across a range of
distances and environments,
Euclid Collaboration, Marleau F.R., Habas R., Carollo D., Tortora C.,
Duc P.-A., Sola E., Saifollahi T., Fugenschuh M., Walmsley M., Zoller R.,
Ferre-Mateu A., Cantiello M., Urbano M., Saremi E., Ragusa R., Laureijs R.,
Hilker M., Muller O., Poulain M., Peletier R.F., Sprenger S.J., Marchal O.,
Aghanim N., Altieri B., Amara A., Andreon S., Auricchio N., Aussel H.,
Baccigalupi C., Baldi M., Balestra A., Bardelli S., Basset A., Battaglia P.,
Bender R., Biviano A., Bonchi A., Bonino D., Branchini E., Brescia M.,
Brinchmann J., Camera S., Canas-Herrera G., Capobianco V., Carbone C.,
Carretero J., Casas S., Castellano M., Castignani G., Cavuoti S.,
Chambers K.C., Cimatti A., Colodro-Conde C., Congedo G., Conselice C.J.,
Conversi L., Copin Y., Corcione L., Courbin F., Courtois H.M., Cropper M.,
Cuillandre J.-C., Da Silva A., Degaudenzi H., De Lucia G., Di Giorgio A.M.,
Dolding C., Dole H., Dubath F., Dupac X., Dusini S., Escoffier S.,
Fabricius M., Farina M., Faustini F., Ferriol S., Fosalba P., Fotopoulou S.,
Frailis M., Franceschi E., Franzetti P., Fumana M., Galeotta S., George K.,
Gillis B., Giocoli C., Granett B.R., Grazian A., Grupp F., Gwyn S.,
Haugan S.V.H., Hoar J., Hoekstra H., Holmes W., Hormuth F., Hornstrup A.,
Hudelot P., Jahnke K., Jhabvala M., Joachimi B., Keihanen E., Kermiche S.,
Kiessling A., Kubik B., Kummel M., Kunz M., Kurki-Suonio H., Lahav O.,
Le Boulc'h Q., Le Brun A.M.C., Le Mignant D., Ligori S., Lilje P.B.,
Lindholm V., Lloro I., Mainetti G., Maino D., Maiorano E., Mansutti O.,
Marcin S., Marggraf O., Martinelli M., Martinet N., Marulli F., Massey R.,
Maurogordato S., McCracken H.J., Medinaceli E., Mei S., Melchior M.,
Mellier Y., Meneghetti M., Merlin E., Meylan G., Mora A., Moresco M.,
Moscardini L., Nakajima R., Neissner 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., Romelli E., Roncarelli M., Rossetti E.,
Rusholme B., Saglia R., Sakr Z., Sanchez A.G., Sapone D., Sartoris B.,
Sauvage M., Schewtschenko J.A., Schirmer M., Schneider P., Scodeggio M.,
Secroun A., Seidel G., Seiffert M., Serrano S., Simon P., Sirignano C.,
Sirri G., Skottfelt J., Stanco L., Steinwagner J., Tallada-Crespi P.,
Tavagnacco D., Taylor A.N., Teplitz H.I., Tereno I., Toft S., Toledo-Moreo R.,
Torradeflot F., Tutusaus I., Valenziano L., Valiviita J., Vassallo T.,
Verdoes Kleijn G., Veropalumbo A., Wang Y., Weller J., Zacchei A.,
Zamorani G., Zerbi F.M., Zucca E., Ballardini M., Bolzonella M., Burigana C.,
Cabanac R., Cappi A., Di Ferdinando D., Escartin Vigo J.A., Gabarra L.,
Huertas-Company M., Martin-Fleitas J., Matthew S., Mauri N., Metcalf R.B.,
Pontinen M., Scottez V., Sereno M., Tenti M., Viel M., Wiesmann M., Akrami Y.,
Andika I.T., Anselmi S., Archidiacono M., Atrio-Barandela F., Bertacca D.,
Bethermin M., Blanchard A., Borgani S., Brown M.L., Bruton S., Buitrago F.,
Calabro A., Camacho Quevedo B., Caro F., Carvalho C.S., Castro T., Cogato F.,
Conseil S., Cooray A.R., Davini S., De Paolis F., Desprez G., Diaz-Sanchez A.,
Di Domizio S., Diego J.M., Dimauro P., Enia A., Franco A., Ganga K.,
Garcia-Bellido J., Gasparetto T., Gaztanaga E., Gianotti F., Gozaliasl G.,
Guidi M., Gutierrez C.M., Hall A., Hernandez-Monteagudo C., Hildebrandt H.,
Kajava J.J.E., Kang Y., Kansal V., Karagiannis D., Kiiveri K.,
Kirkpatrick C.C., Kruk S., Legrand L., Lepori F., Leroy G., Lesci G.F.,
Lesgourgues J., Liaudat T.I., Liu S.J., Macias-Perez J., Mannucci F.,
Maoli R., Martins C.J.A.P., Maurin L., Miluzio M., Monaco P., Moretti C.,
Morgante G., Navarro-Alsina A., Nicastro L., Paterson K., Patrizii L.,
Potter D., Quai S., Radovich M., Rocci P.-F., Sacquegna S., Sahlen M.,
Sanders D.B., Sarpa E., Schultheis M., Sciotti D., Sellentin E., Tanidis K.,
Tao C., Testera G., Teyssier R., Tosi S., Troja A., Tucci M., Venhola A.,
Vergani D., Verza G., Scott D.
<Astron. Astrophys. 711, A10 (2026)>
=2026A&A...711A..10E 2026A&A...711A..10E (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, dwarf ; Photometry, infrared ; Stars, masses
Keywords: galaxies: dwarf - galaxies: evolution -
galaxies: fundamental parameters - galaxies: general -
galaxies: nuclei - galaxies: star clusters: general
Abstract:
The Euclid Q1 fields were selected for calibration purposes in
cosmology and are therefore relatively devoid of nearby galaxies.
However, this is precisely what makes them interesting fields in which
to search for dwarf galaxies in local density environments. We take
advantage of the unprecedented depth, spatial resolution, and field of
view of the Euclid Quick Release (Q1) to build a census of dwarf
galaxies in these regions. We have identified dwarf galaxies in a
representative sample of 25 contiguous tiles in the Euclid Deep Field
North (EDF-N), covering a total area of 14.25 square degrees. The
dwarf galaxy candidates were identified using a semi-automatic
detection method, based on properties measured by the Euclid pipeline
and released as part of the catalogue produced by the MERge Processing
Function (MER PF) pipeline. A selection cut in surface brightness and
magnitude was used to produce an initial dwarf candidate catalogue,
followed by a cut in morphology (removing background spirals) and
IE-HE colour (removing red ellipticals). This catalogue was then
visually classified to produce a final sample of dwarf candidates,
including their morphology, number of nuclei, globular cluster (GC)
richness, and presence of a blue compact centre. We identified 2674
dwarf candidates, corresponding to 188 dwarfs per square degree. The
visual classification of the dwarfs reveals a slightly uneven
morphological mix of 58% ellipticals and 42% irregulars, with very few
potentially GC-rich (1.0%) and nucleated (4.0%) candidates but a
noticeable fraction (6.9%) of dwarfs with blue compact centres. The
distance distribution of 388 (15%) of the dwarf candidates with
spectroscopic redshifts peaks at about 400Mpc. Their stellar mass
distribution confirms our selection effectively identifies dwarfs
while minimising contamination. The most prominent dwarf overdensities
are dominated by dEs, while dIs are more evenly distributed across the
field of view. This work highlights Euclid's remarkable ability to
detect and characterise dwarf galaxies across diverse masses,
distances, and environments.
Description: Table A.1 lists the entire sample of dwarf galaxy
candidates with their morphological and visual properties, ordered by
increasing RA.
Table A.2 lists the Photometric and structural properties of the dwarf
galaxy candidates ordered by increasing RA.
Table A.3. lists the aperture magnitudes and extinction corrections
(EC) of the dwarf galaxy candidates for the Euclid I_E, Y_E, J_E and
H_E photometric bands. The dwarf galaxy candidates are ordered by
increasing RA or equivalently Euclid ID.
Table A.4. lists the stellar mass estimates obtained via the reference
SED fitting setup and all available photometric bands assuming z=0.1
or z=0.05 respectively. The dwarf galaxy candidates are ordered by
increasing RA or equivalently Euclid ID.
Table A.5. lists the stellar mass estimates obtained via the reference
SED fitting setup and all available photometric bands for dwarf galaxy
candidates with spectroscopic redshifts available. The dwarf galaxy
candidates are ordered by increasing RA or equivalently Euclid ID.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 59 2674 Entire sample of dwarf galaxy candidates
table2.dat 87 2674 Photometric and structural properties of the
dwarf galaxy candidates
table3.dat 128 2640 Aperture magnitudes and extinction corrections
(EC) of the dwarf galaxy candidates
table4.dat 71 2635 Stellar mass estimates assuming z=0.1 or z=0.05
table5.dat 86 388 Stellar mass estimates with spectroscopic
redshifts available
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See also:
J/A+A/711/A10 : Euclid (Q1). Census of dwarf galaxies (Euclid Coll., 2026)
J/A+A/711/A16 : X-ray point-like sources of Euclid (Q1) (Euclid Coll.+, 2026)
J/A+A/711/A37 : Ultracool dwarfs in Euclid Deep Fields (Zerjal+, 2026)
J/A+A/711/A38 : Euclid Q1. Photometric studies of known transients
(Duffy+, 2026)
J/A+A/711/A39 : Euclid Q1. Secondary nuclei in ET galaxies (Fabricius+, 2026)
J/A+A/711/A20 : Galaxies of Euclid (Q1) (Euclid Coll.+, 2026)
J/A+A/711/A24 : Euclid Q1. Little red dots properties (Euclid Coll., 2026)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID ? Euclid identifier of the object
21- 30 F10.6 deg RAdeg Right ascension (J2000) of the dwarf galaxy
candidate
32- 40 F9.6 deg DEdeg Declination (J2000) of the dwarf galaxy
candidate
42- 43 A2 --- Morph Morphological type of the dwarf galaxy
candidate
45- 47 A3 --- GC-rich Yes if dwarf galaxy candidate is GC-rich,
No otherwise
49- 51 A3 --- Nucleated Yes if dwarf galaxy candidate is nucleated,
No otherwise
53- 55 A3 --- Disturbed Yes if dwarf galaxy candidate has a
disturbed Morphology, No otherwise
57- 59 A3 --- Blue-cored Yes if dwarf galaxy candidate is
blue-cored, No otherwise
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID ? Euclid identifier of the object
21- 30 F10.6 deg RAdeg Right ascension (J2000) of the
dwarf galaxy candidate
32- 40 F9.6 deg DEdeg Declination (J2000) of the
dwarf galaxy candidate
42- 47 F6.2 mag IEmag ? Magnitude in Euclid I_E band
49- 53 F5.2 mag e_IEmag ? Magnitude uncertainty in Euclid I_E band
55- 61 F7.2 arcsec+2 Area ? Segmentation area of the
dwarf galaxy candidate
63- 67 F5.2 --- ell ? Ellipticity of the dwarf galaxy candidate
69- 74 F6.2 deg PA []? Position angle of the
dwarf galaxy candidate
76- 81 F6.2 mag/arcsec2 SB ? Surface brightness of the
dwarf galaxy candidate
83- 87 F5.2 mag/arcsec2 e_SB ? Surface brightness uncertainty
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID Euclid identifier of the object (1)
20 A1 --- n_ID [*] Note (1)
22- 27 F6.2 mag IEmag Magnitude in Euclid I_E band
29- 33 F5.2 mag e_IEmag Magnitude uncertainty in Euclid I_E band
35- 40 F6.3 mag EC(IE) Extinction correction for Euclid I_E band
42- 47 F6.3 mag e_EC(IE) Extinction correction uncertainty for
Euclid I_E band
49- 54 F6.2 mag YEmag ? Magnitude in Euclid Y_E band
56- 60 F5.2 mag e_YEmag Magnitude uncertainty in Euclid Y_E band
62- 67 F6.3 mag EC(YE) Extinction correction for Euclid Y_E band
69- 74 F6.3 mag e_EC(YE) Extinction correction uncertainty for
Euclid Y_E band
76- 81 F6.2 mag JEmag ? Magnitude in Euclid J_E band
83- 87 F5.2 mag e_JEmag Magnitude uncertainty in Euclid J_E band
89- 94 F6.3 mag EC(JE) Extinction correction for Euclid J_E band
96-101 F6.3 mag e_EC(JE) Extinction correction uncertainty for
Euclid J_E band
103-108 F6.2 mag HEmag ? Magnitude in Euclid H_E band
110-114 F5.2 mag e_HEmag Magnitude uncertainty in Euclid H_E band
116-121 F6.3 mag EC(HE) Extinction correction for Euclid H_E band
123-128 F6.3 mag e_EC(HE) Extinction correction uncertainty for
Euclid H_E band
--------------------------------------------------------------------------------
Note (1): * denotes the dwarf candidates for which the colour information is
affected by image defects.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID Euclid identifier of the object
21- 30 F10.6 deg RAdeg Right ascension (J2000) of the
dwarf galaxy candidate
32- 40 F9.6 deg DEdeg Declination (J2000) of the
dwarf galaxy candidate
42- 46 F5.2 [Msun] logM*z0.1 Stellar mass estimate assuming z=0.1
48- 51 F4.2 [Msun] e_logM*z0.1 Lower uncertainty bound for the stellar mass
estimate assuming z=0.1
53- 56 F4.2 [Msun] E_logM*z0.1 Upper uncertainty bound for the stellar mass
estimate assuming z=0.1
58- 61 F4.2 [Msun] logM*z0.05 Stellar mass estimate assuming z=0.05
63- 66 F4.2 [Msun] e_logM*z0.05 Lower uncertainty bound for the stellar mass
estimate assuming z=0.05
68- 71 F4.2 [Msun] E_logM*z0.05 Upper uncertainty bound for the stellar mass
estimate assuming z=0.05
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID Euclid identifier of the object
21- 30 F10.6 deg RAdeg Right ascension (J2000) of the
dwarf galaxy candidate
32- 40 F9.6 deg DEdeg Declination(J2000) of the
dwarf galaxy candidate
42- 46 F5.2 [Msun] logM*zspAll Stellar mass estimate assuming z=z_spec
using all bands
48- 51 F4.2 [Msun] e_logM*zspAll Lower uncertainty bound for the stellar
mass estimate assuming z=z_spec
using all bands
53- 56 F4.2 [Msun] E_logM*zspAll Upper uncertainty bound for the stellar
mass estimate assuming z=z_spec
using all bands
58- 61 F4.2 [Msun] logM*zspE Stellar mass estimate assuming z=z_spec
using only Euclid bands
63- 66 F4.2 [Msun] e_logM*zspE Lower uncertainty bound for the stellar mass
estimate assuming z=z_spec
using only Euclid bands
68- 71 F4.2 [Msun] E_logM*zspE Upper uncertainty bound for the stellar mass
estimate assuming z=z_spec
using only Euclid bands
73- 76 F4.2 [Msun] logM*zspSB Stellar mass estimate assuming z=z_spec
using single burst model (all bands)
78- 81 F4.2 [Msun] e_logM*zspSB Lower uncertainty bound for the stellar mass
estimate assuming z=z_spec
using single burst model (all bands)
83- 86 F4.2 [Msun] E_logM*zspSB Upper uncertainty bound for the stellar mass
estimate assuming z=z_spec
using single burst model (all bands)
--------------------------------------------------------------------------------
Acknowledgements:
Francine Marleau, francine.marleau(at)uibk.ac.at
(End) Patricia Vannier [CDS] 04-Sep-2025