LEGGOS: A Shocking Lack of Evidence for Shocks at sub-kiloparsec Scales at 2 < z < 4

@misc{cleri2026leggos,
  title = {{LEGGOS: A Shocking Lack of Evidence for Shocks at sub-kiloparsec Scales at 2 < z < 4}},
  author = {Nikko J. Cleri and Taylor A. Hutchison and Brian Welch and Gourav Khullar and Matthew B. Bayliss and Håkon Dahle and Michael Florian and Michael D. Gladders and Connor Luettgenau and Rion Oh and Jane R. Rigby and T. Emil Rivera-Thorsen and Julissa Sarmiento and Keren Sharon},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.07850},
  eprint = {2609.07850},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.07850},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - LEGGOS: A Shocking Lack of Evidence for Shocks at sub-kiloparsec Scales at 2 < z < 4
AU  - Nikko J. Cleri
AU  - Taylor A. Hutchison
AU  - Brian Welch
AU  - Gourav Khullar
AU  - Matthew B. Bayliss
AU  - Håkon Dahle
AU  - Michael Florian
AU  - Michael D. Gladders
AU  - Connor Luettgenau
AU  - Rion Oh
AU  - Jane R. Rigby
AU  - T. Emil Rivera-Thorsen
AU  - Julissa Sarmiento
AU  - Keren Sharon
PY  - 2026
DA  - 2026/09/07
PB  - arXiv
DO  - 10.48550/arxiv.2609.07850
UR  - https://arxiv.org/abs/2609.07850
AB  - Here we present the first systematic search for shocks in six gravitationally lensed galaxies at 2.37 < z < 3.625 with JWST/NIRSpec integral field spectroscopy from the LEnsing and Galaxy Growth: Observing Substructures (LEGGOS) survey. We employ diagnostics that utilize the fluxes and kinematics of shock-sensitive rest-frame optical emission lines H\b{eta}, [O iii] λ5008, [O i] λ6302, Hα, [N ii] λ6585, and [S ii] λλ6718, 6733. We find that, on pixel, clump, and galaxy-integrated scales, the LEGGOS spectra show minimal if any evidence for shocks. The image plane pixels are < 8% within the shock regions of the rest-frame optical line ratio diagnostics for any individual galaxy, and the shock-identified pixels do not show a coherent spatial structure. We also leverage MAPPINGS V shock models to infer shock velocities from the observed emission lines, and find that the distributions of inferred shock velocities are inconsistent with those expected for shock-dominated gas. Altogether, none of these methods provide significant evidence for shocks in the six LEGGOS sources. We conclude by discussing the implications of the lack of evidence for shocks in the broader context of galaxy evolution at cosmic noon and earlier epochs.
ER  -