KiDS J1447-0149: The first spatially resolved spectroscopy of a relic galaxy beyond the local universe. An old high-dispersion core embedded in a compact rotating stellar structure

@misc{hartke2026kids,
  title = {{KiDS J1447-0149: The first spatially resolved spectroscopy of a relic galaxy beyond the local universe. An old high-dispersion core embedded in a compact rotating stellar structure}},
  author = {Johanna Hartke and Chiara Spiniello and Michele Cappellari and Davide Bevacqua and Enrico Congiu and Anna Ferré-Mateu and Adriano Poci and Claudia Pulsoni and Magda Arnaboldi and Giuseppe D'Ago and Michalina Maksymowicz-Maciata and Paolo Saracco and Diana Scognamiglio and David A. Simon and Crescenzo Tortora and Petri Väisänen},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.21658},
  eprint = {2609.21658},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.21658},
}

TY  - UNPB
TI  - KiDS J1447-0149: The first spatially resolved spectroscopy of a relic galaxy beyond the local universe. An old high-dispersion core embedded in a compact rotating stellar structure
AU  - Johanna Hartke
AU  - Chiara Spiniello
AU  - Michele Cappellari
AU  - Davide Bevacqua
AU  - Enrico Congiu
AU  - Anna Ferré-Mateu
AU  - Adriano Poci
AU  - Claudia Pulsoni
AU  - Magda Arnaboldi
AU  - Giuseppe D'Ago
AU  - Michalina Maksymowicz-Maciata
AU  - Paolo Saracco
AU  - Diana Scognamiglio
AU  - David A. Simon
AU  - Crescenzo Tortora
AU  - Petri Väisänen
PY  - 2026
DA  - 2026/09/18
PB  - arXiv
DO  - 10.48550/arxiv.2609.21658
UR  - https://arxiv.org/abs/2609.21658
AB  - Relic galaxies are the descendants of high-redshift compact quiescent systems. We present the first spatially resolved spectroscopic study of J1447-0149, a massive relic at z=0.21, observed with MUSE+AO. We characterize its kinematics and stellar population properties to probe its spatially resolved mass assembly history. We measured stellar kinematics with sub-kpc bin sizes, covering ∼ 1.4 effective radii. We then used a coarser three-bin configuration informed by the kinematics to recover the higher-order velocity moments, [α/Fe], stellar age and metallicity. We reconstructed the star formation history and computed the degree of relicness (DoR). MUSE data reveal a velocity gradient, showing that J1447-0149 is not purely pressure supported. The velocity-dispersion field displays a central peak, reaching σ_⋆=233±13 km s^−1, substantially larger than previous seeing-limited measurements (σ_⋆ =187 ± 9 km s^−1). The h_3--V_⋆ anti-correlation and mildly positive h_4 values support a composite structure, with a rotating stellar component surrounding a compact dynamically hot core. This central, dispersion-dominated region is also the oldest and most metal-rich component. Its SFH rises rapidly, with the stellar mass assembled within ∼2 Gyr after the Big Bang, and reaches DoR=0.9^+0.1_−0.2. The two outer bins have a DoR value of DoR=0.8±0.2, consistent with the central bin, but possibly indicating slightly longer formation times. Spatially resolved spectroscopy has been crucial to confirm the relic nature of J1447-0149, linking resolved morphology, kinematics, and stellar populations to constrain the early assembly of its central spheroid and surrounding disk.
ER  -