MATLAS-42, A Globular Cluster-Rich Ultra-Diffuse Galaxy That Diverges from the "Failed Galaxy'' Formation Pathway
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| author | Gannon, Jonah S. Forbes, Duncan A. Marleau, Francine R. Ferré-Mateu, Anna Romanowsky, Aaron J. Buzzo, Maria Luisa Brodie, Jean P. |
| author_facet | Gannon, Jonah S. Forbes, Duncan A. Marleau, Francine R. Ferré-Mateu, Anna Romanowsky, Aaron J. Buzzo, Maria Luisa Brodie, Jean P. |
| contents | To date, there has been significant interest in globular cluster (GC)-rich ultra-diffuse galaxies (UDGs) and the evidence that they have formed via an unexpected, ``failed galaxy'' formation pathway. The majority of the evidence for ``failed galaxy'' UDGs originates from spectroscopic observations targeting passive GC-rich UDGs, with a focus on those residing in galaxy clusters. In this work, we study the gas-rich, GC-rich group UDG MATLAS-42 and derive its stellar population properties using the Keck Cosmic Web Imager. We measure a redshift for the galaxy ($V_{\rm R, \star}=2433\pm8$~km s$^{-1}$), confirming the previous assumptions that it is both part of the NGC~502 group and has an associated HI-reservoir ($V_{\rm R,HI}=2423\pm 15$~km s$^{-1}$). We measure integrated stellar populations and find the galaxy to be both young (mass-weighted age $=3.2^{+2.6}_{-1.5}$Gyr) and of average-to-low metallicity ($[M/H]=-1.19^{+0.42}_{-0.30}$ dex). When considering these properties in the context of the galaxy's formation, we note it likely does not follow the ``failed galaxy'' formation pathway commonly attributed to GC-rich, cluster UDGs, as it has experienced recent star formation. At most it started failed, however, it has recently rejuvenated its star formation. Finally, we build a toy model of the passive evolution of this galaxy, finding that its relative GC-richness (i.e., $M_{\rm GC}/M_\star$) will likely decrease with time as GCs slowly evaporate/disrupt to contribute to the stellar mass of the galaxy. Due to this, we hypothesise that it is likely not a low redshift analogue of the progenitor to a ``failed galaxy'' UDGs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_18046 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | MATLAS-42, A Globular Cluster-Rich Ultra-Diffuse Galaxy That Diverges from the "Failed Galaxy'' Formation Pathway Gannon, Jonah S. Forbes, Duncan A. Marleau, Francine R. Ferré-Mateu, Anna Romanowsky, Aaron J. Buzzo, Maria Luisa Brodie, Jean P. Astrophysics of Galaxies To date, there has been significant interest in globular cluster (GC)-rich ultra-diffuse galaxies (UDGs) and the evidence that they have formed via an unexpected, ``failed galaxy'' formation pathway. The majority of the evidence for ``failed galaxy'' UDGs originates from spectroscopic observations targeting passive GC-rich UDGs, with a focus on those residing in galaxy clusters. In this work, we study the gas-rich, GC-rich group UDG MATLAS-42 and derive its stellar population properties using the Keck Cosmic Web Imager. We measure a redshift for the galaxy ($V_{\rm R, \star}=2433\pm8$~km s$^{-1}$), confirming the previous assumptions that it is both part of the NGC~502 group and has an associated HI-reservoir ($V_{\rm R,HI}=2423\pm 15$~km s$^{-1}$). We measure integrated stellar populations and find the galaxy to be both young (mass-weighted age $=3.2^{+2.6}_{-1.5}$Gyr) and of average-to-low metallicity ($[M/H]=-1.19^{+0.42}_{-0.30}$ dex). When considering these properties in the context of the galaxy's formation, we note it likely does not follow the ``failed galaxy'' formation pathway commonly attributed to GC-rich, cluster UDGs, as it has experienced recent star formation. At most it started failed, however, it has recently rejuvenated its star formation. Finally, we build a toy model of the passive evolution of this galaxy, finding that its relative GC-richness (i.e., $M_{\rm GC}/M_\star$) will likely decrease with time as GCs slowly evaporate/disrupt to contribute to the stellar mass of the galaxy. Due to this, we hypothesise that it is likely not a low redshift analogue of the progenitor to a ``failed galaxy'' UDGs. |
| title | MATLAS-42, A Globular Cluster-Rich Ultra-Diffuse Galaxy That Diverges from the "Failed Galaxy'' Formation Pathway |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2602.18046 |