The extragalactic science of the KMOS VVVX-GalCen spectroscopic survey II: Discovery of a galaxy cluster at z = 0.089 behind the Galactic plane

@misc{schmidt2026extragalactic,
  title = {{The extragalactic science of the KMOS VVVX-GalCen spectroscopic survey II: Discovery of a galaxy cluster at z = 0.089 behind the Galactic plane}},
  author = {E. O. Schmidt and C. Valotto and C. Villalon and L. D. Baravalle and J. L. Nilo-Castellón and M. V. Alonso and M. Soto and M. Gómez and D. Minniti and W. Weidmann and D. Mast and C. Obasi and D. Alvarez Rocha and S. Federle and R. K. Saito and V. D. Ivanov and M. G. Navarro and Z. Guo and A. Pichel and I. Petralia and V. Fermiano and A. Luna and M. Lad and J. Osses and R. Pignata and V. Valdivia Rojas and P. Marchant Cortes and E. G. Rivera and G. Ferrero and N. Masetti and J. Borissova and J. G. Fernández-Trincado and C. Cáceres and F. Nogueras-Lara and D. Galdeano and F. Fortuni},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.38811},
  eprint = {2610.38811},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.38811},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - The extragalactic science of the KMOS VVVX-GalCen spectroscopic survey II: Discovery of a galaxy cluster at z = 0.089 behind the Galactic plane
AU  - E. O. Schmidt
AU  - C. Valotto
AU  - C. Villalon
AU  - L. D. Baravalle
AU  - J. L. Nilo-Castellón
AU  - M. V. Alonso
AU  - M. Soto
AU  - M. Gómez
AU  - D. Minniti
AU  - W. Weidmann
AU  - D. Mast
AU  - C. Obasi
AU  - D. Alvarez Rocha
AU  - S. Federle
AU  - R. K. Saito
AU  - V. D. Ivanov
AU  - M. G. Navarro
AU  - Z. Guo
AU  - A. Pichel
AU  - I. Petralia
AU  - V. Fermiano
AU  - A. Luna
AU  - M. Lad
AU  - J. Osses
AU  - R. Pignata
AU  - V. Valdivia Rojas
AU  - P. Marchant Cortes
AU  - E. G. Rivera
AU  - G. Ferrero
AU  - N. Masetti
AU  - J. Borissova
AU  - J. G. Fernández-Trincado
AU  - C. Cáceres
AU  - F. Nogueras-Lara
AU  - D. Galdeano
AU  - F. Fortuni
PY  - 2026
DA  - 2026/10/28
PB  - arXiv
DO  - 10.48550/arxiv.2610.38811
UR  - https://arxiv.org/abs/2610.38811
AB  - The Zone of Avoidance (ZoA) continues to represent the most significant incompleteness in the extragalactic census of the Local Universe. It is evident that photometric surveys alone are insufficient to establish whether the galaxy overdensities detected therein are physical systems or projections along the line of sight. We present the first spectroscopic results of the extragalactic science area of the KMOS VVVX-GalCen Spectroscopic Survey, demonstrating how near-infrared (NIR) spectroscopy can reveal and dynamically characterise galaxy clusters hidden by the Milky Way. A photometric overdensity of 19 galaxy candidates was identified in the VVV NIRGC III catalogue, centred at (l,b)=(274.05^∘,+2.85^∘) with a mean interstellar extinction of A_K_s=0.2 mag; 16 of these candidates were observed with VLT/KMOS in the HK grating and yielded spectra with reliable cross-correlation radial velocities. A total of 14 galaxies form a compact structure with a mean redshift of ⟨ z ⟩ = 0.089 ± 0.001, which corresponds to a mean radial velocity ⟨ cz ⟩ = 26660 ± 170 km/s, while two are foreground galaxies. The rest-frame line-of-sight velocity dispersion is σ_v = 560^+110_−120 km/s, implying an indicative dynamical mass of M_200 = 1.9^+0.7_−1.1 × 10^14 M_⊙ (based on members within the cluster core ∼ 0.4 r_200) and placing the system in the poor-cluster regime. Of these 14 cluster members, 13 also lie within the 2σ scatter of the fitted near-IR red sequence. The other two galaxies are foreground objects that lie outside this range.
ER  -