Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra I cluster: III. Untangling UDG 32 from the stripped filaments of NGC 3314A with multi-wavelength data
Journal article, 2025
Context. UDG 32 is an ultra-diffuse galaxy (UDG) candidate in the Hydra I cluster that was discovered in the extended network of stellar filaments of the jellyfish galaxy NGC 3314A. This jellyfish galaxy is affected by ram pressure stripping and it is hypothesised that UDG 32 may have formed from this stripped material. Aims. The aim of this paper is to address whether UDG 32 can be associated with the stripped material of NGC 3314A and to constrain its formation scenario in relation to its environment. Methods. We use new integral-field spectroscopic data from the MUSE large programme 'LEWIS'in conjunction with deep multi-band photometry to constrain the kinematics of UDG 32 via spectral fitting and its stellar population properties with spectral energy distribution fitting. Results. The new MUSE data allow us to reveal that the stripped material from NGC 3314A, traced by emission lines such as Hα, extends much further from its parent galaxy than previously known, completely overlapping with UDG 32 in projection, and with ram pressure induced star formation. We determine the line-of-sight velocity of UDG 32 to be vLOS = 3080 ± 120 km s-1 and confirm that UDG 32 is part of the same kinematic structure as NGC 3314A, the Hydra I cluster south-east subgroup. By fitting the UV and optical spectral energy distribution obtained from deep multi-band photometry, we constrain the stellar population properties of UDG 32. We determine its mass-weighted age to be 7.7-2.8+2.9 Gyr and its metallicity to be [M/H] = 0.07-0.32+0.19 dex. We confirm the presence of two globular clusters (GCs) in the MUSE field of view, bound to the Hydra I cluster rather than to UDG 32, making them part of the Hydra I intracluster GC population. Conclusions. The metal-rich and intermediate-age nature of UDG 32 points towards its formation from pre-enriched material in the south-east group of the Hydra I cluster that was liberated from a more massive galaxy via tidal or ram-pressure stripping, but we cannot establish a direct link to the ram-pressure stripped material from NGC 3314A.
Galaxies: individual: UDG 32
Galaxies: clusters: individual: Hydra I
Galaxies: formation
Galaxies: individual: NGC 3314A
Author
J. Hartke
University of Turku
Tuorla Observatory
E. Iodice
Osservatorio Astronomico di Capodimonte
Marco Gullieuszik
Istituto nazionale di astrofisica (INAF)
M. Mirabile
European Southern Observatory (ESO)
Istituto nazionale di astrofisica (INAF)
Gran Sasso Science Institute (GSSI)
C. Buttitta
Osservatorio Astronomico di Capodimonte
G. Doll
Osservatorio Astronomico di Capodimonte
University of Naples Federico II
G. D'ago
University of Cambridge
C. C. De La Casa
Spanish National Research Council (CSIC)
Kelley Michelle Hess
Netherlands Institute for Radio Astronomy (ASTRON)
Chalmers, Space, Earth and Environment, Onsala Space Observatory
R. Kotulla
University of Wisconsin
B. M. Poggianti
Istituto nazionale di astrofisica (INAF)
M. Arnaboldi
European Southern Observatory (ESO)
M. Cantiello
Istituto nazionale di astrofisica (INAF)
E. M. Corsini
Istituto nazionale di astrofisica (INAF)
University of Padua
J. Falcón-Barroso
Instituto de Astrofísica de Canarias
University of La Laguna
D. A. Forbes
Swinburne University of Technology
M. Hilker
European Southern Observatory (ESO)
S. Mieske
European Southern Observatory Santiago
M. Rejkuba
European Southern Observatory (ESO)
M. Spavone
Osservatorio Astronomico di Capodimonte
C. Spiniello
Osservatorio Astronomico di Capodimonte
University of Oxford
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 695 A91Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202452975