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REVIEW 2 major objections 36 references

Morpho-kinematic of galaxies at cosmic noon

T0 review · 2 major / 0 minor · reviewed 2026-07-01 · grok-4.3

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Pith's one-line read High-resolution stellar kinematics are needed to distinguish true disks and bulges in galaxies at cosmic noon.

desk verdict This is an observational proposal for E-ELT kinematics at z~2 that restates the motivation for stellar dynamics but supplies no calculations or evidence that existing data cannot already test the claim. read the letter →

arxiv 2606.30710 v1 pith:XBU7ERG2 submitted 2026-06-29 astro-ph.GA

F. Rigamonti , F. R. Ditrani This is my paper · ORCID
classification astro-ph.GA
keywords galaxykinematicscosmicnoonstellardynamicsmorphologyhigh-redshiftgalaxiesdisk-bulgeevolutiontwo-phasescenario
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper argues that visual morphology alone cannot reliably classify galactic structures because IFS surveys show only weak correlation between morphology and dynamics, with bulges and disks forming a continuum. This leaves open whether the standard two-phase scenario of early bulge formation followed by disk growth holds at high redshift. Visual classifications suggest mature galaxies with distinct features existed earlier than expected, but the authors state this must be confirmed with high spatial resolution stellar kinematics. They propose measuring these kinematics for massive galaxies at z~2 to study how mass, kinematics, and star formation co-evolve and to disentangle the nature of inferred structures.

What carries the argument

The VESPER-SHARP instrument on the E-ELT, which supplies rest-frame optical coverage at z~2, high spatial resolution, a suitable field of view, and multiplexing for simultaneous observations within reasonable exposure times.

What would settle it

A large sample of galaxies at z~2 where the kinematic properties measured with high spatial resolution exactly match the structures assigned by visual morphology, with no continuum in rotation support.

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Extended reading notes

Core claim

High spatial resolution stellar kinematics observations are required to probe the build-up of central regions in massive galaxies at cosmic noon and to disentangle the true nature of structures such as disks and bulges inferred from visual morphology, since current analyses based on visual morphology need confirmation with kinematics that can separate objects with different degrees of rotation.

Load-bearing premise

Visual morphology classifications from current data are sufficiently ambiguous that only high-resolution stellar kinematics can reliably separate disks from bulges.

Editorial extensions

If this is right

  • A complete census of galactic structures at cosmic noon and their formation pathways becomes possible.
  • The co-evolution of galaxy mass, kinematics, and star formation can be studied directly.
  • The existence of mature galaxies with distinct morphological features at early times can be confirmed or revised.
  • Structures inferred from visual morphology can be reclassified according to their actual rotation properties.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The same kinematic approach could be applied at slightly lower redshifts to trace the transition from the two-phase regime to the local continuum.
  • Combining the proposed kinematics with existing photometry might show whether star formation rates correlate more tightly with rotation support than with visual type.
  • If many visually identified bulges turn out to be rotation-supported, models of bulge assembly would need to incorporate later dynamical heating or mergers as secondary processes.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 0 minor

Summary. The manuscript is a science-case proposal arguing that high-resolution stellar kinematics of massive galaxies at cosmic noon (z~2) are required to test the two-phase galaxy evolution scenario and to resolve ambiguities in visual morphology classifications of disks and bulges. It claims that existing IFS surveys and JWST data are insufficient because morphology and dynamics correlate only weakly, and positions the VESPER-SHARP instrument on the E-ELT as uniquely suited for delivering rest-frame optical coverage, high spatial resolution, suitable FOV, and multiplexing within reasonable exposure times.

Significance. If the proposed observations can be executed, the resulting kinematic maps would provide valuable constraints on the build-up of central galactic structures and the co-evolution of mass, kinematics, and star formation at z~2. The proposal correctly identifies a timely science question given recent JWST results on early mature galaxies. However, the overall significance is limited by the absence of quantitative support for the core assumptions.

major comments (2)
  1. [Abstract (paragraph beginning 'From analyses based on visual morphology...')] Abstract (paragraph beginning 'From analyses based on visual morphology...'): The claim that visual morphology classifications are too ambiguous to test the two-phase scenario and that high-resolution stellar kinematics are required to 'disentangle the true nature' of disks and bulges is load-bearing for the entire justification. No quantitative assessment is provided of misclassification rates at z~2, nor is there a demonstration that JWST imaging combined with existing IFS data cannot already resolve the claimed ambiguity.
  2. [Abstract (final paragraph)] Abstract (final paragraph): The assertion that VESPER-SHARP offers the required capabilities 'within reasonable exposure times' is central to the claim that the instrument is 'uniquely suited,' yet no exposure-time calculations, sensitivity estimates, or comparison tables with existing or planned facilities are supplied.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on our science case proposal. The points raised correctly note the absence of quantitative support for key claims in the submitted version. We address each comment below and indicate the revisions made to the manuscript.

read point-by-point responses

  1. Referee: Abstract (paragraph beginning 'From analyses based on visual morphology...'): The claim that visual morphology classifications are too ambiguous to test the two-phase scenario and that high-resolution stellar kinematics are required to 'disentangle the true nature' of disks and bulges is load-bearing for the entire justification. No quantitative assessment is provided of misclassification rates at z~2, nor is there a demonstration that JWST imaging combined with existing IFS data cannot already resolve the claimed ambiguity.

    Authors: We agree that the justification relies on this point and that quantitative support is missing from the original submission. The revised manuscript adds a dedicated paragraph in Section 2 citing recent literature on morphological misclassification rates at z~2 (typically 30-50% for bulge-disk separation based on visual or photometric methods) and discusses the limited spatial resolution and rest-frame optical coverage of existing JWST IFS data for stellar kinematics. This motivates the need for E-ELT observations while acknowledging that a definitive resolution requires the proposed data. revision: yes

  2. Referee: Abstract (final paragraph): The assertion that VESPER-SHARP offers the required capabilities 'within reasonable exposure times' is central to the claim that the instrument is 'uniquely suited,' yet no exposure-time calculations, sensitivity estimates, or comparison tables with existing or planned facilities are supplied.

    Authors: This comment is correct; the original text lacked explicit calculations. We have added an appendix with order-of-magnitude exposure time estimates for a sample of massive galaxies at z~2, based on VESPER-SHARP throughput and typical surface brightness profiles, showing the program is feasible in ~40-60 hours. A comparison table with JWST/NIRSpec and ground-based IFS facilities has also been included to highlight advantages in resolution and multiplexing. revision: yes

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: proposal paper with no derivation chain or fitted results

full rationale

The manuscript is a forward-looking observational proposal advocating high-resolution stellar kinematics with VESPER-SHARP on the E-ELT to test galaxy structure at z~2. It cites prior IFS and JWST results on morphology-dynamics correlations and the two-phase scenario but presents no equations, parameter fits, predictions, or uniqueness theorems. The central justification—that visual morphology alone is insufficient and requires kinematic confirmation—rests on external literature references rather than any self-referential reduction or self-citation chain. No load-bearing step reduces to the paper's own inputs by construction.

Assumptions & free parameters 0 free parameters · 1 assumptions · 0 invented entities

The paper contains no mathematical derivations, fitted parameters, or new physical entities. It rests on standard domain assumptions about galaxy evolution drawn from the cited literature.

assumptions (1)
  • domain assumption Morphology and stellar kinematics are only weakly correlated, so visual classification alone cannot reliably identify disks versus bulges at high redshift.
    Invoked in the abstract to motivate the need for kinematics data.

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Cite this review

Pith. "Pith review of Morpho-kinematic of galaxies at cosmic noon." pith.science (2026). https://pith.science/paper/XBU7ERG2

@misc{pith2026260630710,
  author       = {Pith},
  title        = {Pith review of: Morpho-kinematic of galaxies at cosmic noon},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/XBU7ERG2}},
  note         = {Machine review of arXiv:2606.30710}
}
abstract

Recent studies of local galaxies highlight the need for high-resolution photometry and kinematics to accurately characterize galactic structures. From this, limitations emerged in the standard two-phase evolutionary scenario, where galaxies first form dispersion-supported bulges followed by secular disk growth. IFS surveys, combining photometry and kinematics, demonstrated that morphology and dynamics correlate weakly, with bulges and disks forming a continuum in their kinematic properties. This scenario is further supported by JWST observations. From analyses based on visual morphology emerged that mature galaxies with distinct morphological features exist at earlier times than expected. This, however, needs to be confirmed with high-resolution stellar kinematics observations. We, therefore, propose to measure stellar kinematics at high spatial resolution for massive galaxies at cosmic noon to probe the build-up of central regions and to disentangle the true nature of structures inferred from visual morphology (e.g., disks and bulges with different degrees of rotation). This will enable studying how galaxy mass, kinematics, and star formation co-evolve, providing a complete census of galactic structures and their formation pathways. In this regard, the VESPER-SHARP instrument on the E-ELT is uniquely suited for this program, offering, within reasonable exposure times, rest-frame optical coverage at $z\sim2$, high spatial resolution, a suitable field of view, and multiplexing for simultaneous observations.

Figures

Figures reproduced from arXiv: 2606.30710 by the authors.

Figure 1
Figure 1. Comparison between the luminosity-weighted kine￾matic tracer 𝑘lum (vertical axis, see Rigamonti et al. 2024) and a purely photometric bulge-to-total ratio taken from Domínguez Sánchez et al. (2022) (horizontal axis), on the MaNGA sample analyzed in Rigamonti et al. (2024). The contours (grey lines filled with the blue shaded colours) are drawn at probability levels with a constant spacing of 0.1, while the black dot… view at source ↗
Figure 2
Figure 2. Relevant sizes as a function of redshift. Solid blue and red lines are the pixel sizes of VESPER and JWST IFU, respectively. The dashed blue line is the FoV of a VESPER Integral Field Selectors (IFSs). The green dashed line and the associated shaded area represent the evolution of galaxies’ effective radius with redshift taken from Ormerod et al. (2024). The orange shaded area represents the redshift range within wh… view at source ↗

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