Dissecting ultra-diffuse galaxies in the field
Abstract
Context. Ultra-diffuse galaxies (UDGs) in the field are faint, diffuse systems that remain poorly represented in the literature due to the need for spectroscopic confirmation and the difficulty of obtaining high S/N emission line measurements. Aims. We present a spectroscopic study of 17 blue UDG candidates in the field using optical emission lines to confirm their diffuse nature and properties. Methods. We derived spectroscopic redshifts(zspec) for our field UDG candidates. We then computed their effective radii (reff) and central surface brightnesses (μ0,g). We measured the Hα and Hβ emission line fluxes in the 17 spectra and derived star-formation rates (SFR) from the line-luminosity relation. We performed forced photometry on our sample to obtain photometric fluxes and applied an aperture correction on the Hα integrated fluxes, propagating the correction to the derived SFRs. We then computed stellar masses (M*) using colour relations and estimated dust attenuation and corrected the SFRs accordingly. Two sources were further examined as potential giant low surface-brightness galaxies(GLSBGs). Results. We identify nine confirmed UDGs, eight other low surface-brightness galaxies (LSBGs), including one GLSBG. The zspec of our field UDGs span a range of $0.015-0.037$, their reff spans $1.69-4.99$ kpc and μ0,g between 24.05−24.98 mag arcsec−2. Galaxies exhibit low to moderate dust content, with an average V-band attenuation of 0.29 mag. The spectroscopically confirmed UDGs presented in this work, after the aperture correction performed, lie along the star-forming main sequence. Conclusions. Our results indicate that blue field UDGs are characterised by heterogeneous dust attenuation and occupy the same region of the star formation-stellar mass plane as dwarf LSBGs.
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BibTeX
@misc{vanzanella2026dissecting,
title = {{Dissecting ultra-diffuse galaxies in the field}},
author = {A. Vanzanella and K. Malek and Junais and E. Bernaud and A. Gargiulo and H. Thuruthipilly and K. Lisiecki and A. Pollo and M. Scodeggio and P. M. Weilbacher and S. Boissier and P. Franzetti and G. Lorenzon and A. Nanni and C. Adami and R. Gavazzi and O. Ilbert and S. Pal and N. Principi Cavaterra},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.28109},
eprint = {2608.28109},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.28109},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Dissecting ultra-diffuse galaxies in the field
AU - A. Vanzanella
AU - K. Malek
AU - Junais
AU - E. Bernaud
AU - A. Gargiulo
AU - H. Thuruthipilly
AU - K. Lisiecki
AU - A. Pollo
AU - M. Scodeggio
AU - P. M. Weilbacher
AU - S. Boissier
AU - P. Franzetti
AU - G. Lorenzon
AU - A. Nanni
AU - C. Adami
AU - R. Gavazzi
AU - O. Ilbert
AU - S. Pal
AU - N. Principi Cavaterra
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2608.28109
UR - https://arxiv.org/abs/2608.28109
AB - Context. Ultra-diffuse galaxies (UDGs) in the field are faint, diffuse systems that remain poorly represented in the literature due to the need for spectroscopic confirmation and the difficulty of obtaining high S/N emission line measurements. Aims. We present a spectroscopic study of 17 blue UDG candidates in the field using optical emission lines to confirm their diffuse nature and properties. Methods. We derived spectroscopic redshifts(z_spec) for our field UDG candidates. We then computed their effective radii (r_eff) and central surface brightnesses (μ_0,g). We measured the Hα and Hβ emission line fluxes in the 17 spectra and derived star-formation rates (SFR) from the line-luminosity relation. We performed forced photometry on our sample to obtain photometric fluxes and applied an aperture correction on the Hα integrated fluxes, propagating the correction to the derived SFRs. We then computed stellar masses (M_*) using colour relations and estimated dust attenuation and corrected the SFRs accordingly. Two sources were further examined as potential giant low surface-brightness galaxies(GLSBGs). Results. We identify nine confirmed UDGs, eight other low surface-brightness galaxies (LSBGs), including one GLSBG. The z_spec of our field UDGs span a range of $0.015-0.037$, their r_eff spans $1.69-4.99$ kpc and μ_0,g between 24.05−24.98 mag arcsec^−2. Galaxies exhibit low to moderate dust content, with an average V-band attenuation of 0.29 mag. The spectroscopically confirmed UDGs presented in this work, after the aperture correction performed, lie along the star-forming main sequence. Conclusions. Our results indicate that blue field UDGs are characterised by heterogeneous dust attenuation and occupy the same region of the star formation-stellar mass plane as dwarf LSBGs.
ER -