arxiv: 2604.20086 · v1 · submitted 2026-04-22 · ✦ hep-ph · astro-ph.HE

Recognition: unknown

Photon and neutrino fluxes from spheroidal dwarf galaxies in a decaying DM model

A. Carrillo-Monteverde , L. L\'opez-Lozano , F. San Juan-Villegas

Authors on Pith no claims yet

Pith reviewed 2026-05-10 00:46 UTC · model grok-4.3

classification ✦ hep-ph astro-ph.HE

keywords decaying dark matterscalar singletdwarf spheroidal galaxiesgamma-ray fluxneutrino fluxindirect detectionZ2 symmetry

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The pith

A scalar singlet dark matter particle decaying via non-minimal gravitational coupling produces gamma-ray and neutrino fluxes from dwarf spheroidal galaxies that reach detectable levels for certain benchmark parameters.

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

The paper examines a dark matter model in which a scalar singlet remains stable long enough to match the age of the universe thanks to a Z2 symmetry, yet decays slowly through a gravitational interaction term. It calculates the photon and neutrino fluxes that would arrive at Earth from both the Milky Way and fourteen dwarf spheroidal galaxies by integrating over their dark matter density profiles. The authors evaluate three benchmark masses and three coupling strengths that already satisfy cosmological limits and find that the resulting event rates in gamma-ray and neutrino detectors fall inside the observable range in parts of the allowed parameter space. This connects a concrete particle-physics decay channel to multi-messenger signals that existing or near-term instruments could record.

Core claim

In the scalar singlet model, dark matter decays into Standard Model particles through the non-minimal gravitational coupling; the subsequent cascades produce gamma rays and neutrinos whose fluxes, when computed for the density distributions of fourteen dwarf spheroidal galaxies, yield expected event counts that can be reached by selected experiments for the three benchmark points consistent with cosmological constraints.

What carries the argument

The Z2-protected scalar singlet with non-minimal gravitational coupling that sets its decay width, combined with numerical line-of-sight integration of the resulting particle fluxes using the adopted dark matter density profiles of the dwarf galaxies.

If this is right

The gamma-ray component of the signal can be tested directly against existing or upcoming telescope data for the selected dwarfs.
The neutrino component supplies an independent detection channel in large-volume observatories for the same decay process.
Only a limited window of masses and couplings simultaneously satisfies the lifetime requirement and produces fluxes above detector thresholds.
The same calculation framework can be applied uniformly to both the Milky Way and the satellite galaxies to check for spatial consistency.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

A detection in the dwarfs but not at the galactic center would point toward density-linear decay rather than density-squared annihilation.
Tighter upper limits from non-observation would further restrict the allowed coupling values beyond what cosmology alone requires.
The method can be extended to additional dwarfs with improved density measurements or to charged-particle channels for multi-messenger cross-checks.

Load-bearing premise

The chosen benchmark masses and couplings produce a decay lifetime longer than the age of the universe while generating no additional signals that would violate other cosmological or astrophysical bounds.

What would settle it

Absence of the predicted gamma-ray or neutrino excess above background from the directions of the fourteen dwarf galaxies at the flux levels calculated for any of the three benchmark masses would exclude those parameter points.

read the original abstract

In this work, we investigate a decaying dark matter scenario and its associated indirect detection signatures. The model consists of a scalar singlet with a lifetime exceeding the age of the Universe. Stability is ensured by a $Z_2$ symmetry imposed on the Lagrangian, allowing decay through a non-minimal gravitational coupling. The decay of dark matter produces Standard Model particles, which subsequently yield products such as gamma rays, neutrinos, and charged particles. We computed the gamma-ray and neutrino fluxes generated by this candidate in the Milky Way and in 14 dwarf spheroidal galaxies, as well as the corresponding expected number of events in selected experiments, using dedicated numerical tools. Results are presented for three benchmark masses and three coupling values consistent with cosmological constraints, showing that the predicted signals can be observable in specific regions of parameter space.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This paper does routine flux calculations for a decaying scalar DM model in dwarf galaxies but leaves the non-minimal coupling decay width under-specified.

read the letter

The main point is that this work takes a scalar singlet dark matter model with Z2 symmetry and non-minimal gravity coupling, then computes gamma-ray and neutrino fluxes plus expected event rates in the Milky Way and 14 dwarf spheroidal galaxies for three benchmark masses and couplings. The results flag regions where signals might be observable in experiments, using standard numerical tools for the propagation and detection estimates. That supplies some concrete target numbers for indirect detection in a decaying scenario, which is the useful part here. Dwarf galaxies are a sensible choice for low-background targets, and sticking to cosmologically allowed benchmarks keeps the setup grounded in external constraints. The calculations themselves follow established methods for DM decay products, so the numerical side looks like a straightforward extension rather than a new technique. The soft spot is exactly the one flagged in the stress-test note. The decay proceeds through the non-minimal term, yet the abstract and available details give no explicit derivation of the width from the effective Lagrangian, no scaling with mass or coupling strength, and no matching to a UV cutoff. Without that, it is hard to confirm the chosen couplings really produce lifetimes longer than the age of the universe while still yielding detectable fluxes. The paper also skips details on the density profiles adopted for the dwarfs, any error propagation, or direct comparison to current limits, which weakens the observability claims. This is for astroparticle physicists who need sample flux predictions in decaying DM models focused on dwarfs. A reader hunting for new theoretical frameworks or first-principles derivations will not find them, but someone wanting benchmark numbers for specific galaxies could use the outputs as a starting point once the model justification is tightened. It deserves a serious referee because the flux calculations are checkable and could be made more robust with added sections on the decay rate and assumptions. I would send it to peer review with a request to supply the missing derivation and numerical validation.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates indirect detection signatures from a decaying scalar singlet dark matter model stabilized by a Z2 symmetry, with decays induced by a non-minimal gravitational coupling. It calculates gamma-ray and neutrino fluxes from the Milky Way and 14 dwarf spheroidal galaxies, along with expected event rates in selected experiments, for three benchmark dark matter masses and three coupling values consistent with cosmological constraints. The central claim is that the predicted signals can be observable in specific regions of parameter space.

Significance. If the decay rates and numerical flux computations hold, the work supplies concrete, testable predictions for photon and neutrino signals from dwarf galaxies in a decaying DM scenario. This adds targeted benchmarks to the indirect detection literature and could inform observational strategies with gamma-ray and neutrino telescopes.

major comments (2)

[Model Lagrangian and decay process] The derivation of the decay width Γ(φ → SM) from the non-minimal gravitational coupling term is not provided. Without an explicit calculation from the Lagrangian (including any cutoff scale or matching procedure), it is unclear whether the three benchmark coupling values simultaneously satisfy the lifetime > age of the universe requirement and produce the claimed observable fluxes.
[Numerical results and flux calculations] The abstract states that numerical computations demonstrate observability, yet the manuscript supplies no details on the specific tools, DM density profile assumptions for the dSph galaxies, propagation modeling, or validation procedures. This absence prevents verification that the reported fluxes and event rates support the observability conclusion for the benchmark points.

minor comments (2)

The abstract refers to 'dedicated numerical tools' without naming them; specifying the codes (e.g., for decay spectra or flux integration) would aid reproducibility.
A summary table listing the three benchmark masses, couplings, and resulting lifetimes would improve clarity when comparing to cosmological bounds.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their positive summary of our work and for the constructive major comments. We address each point below and have revised the manuscript to incorporate additional details and derivations as requested.

read point-by-point responses

Referee: [Model Lagrangian and decay process] The derivation of the decay width Γ(φ → SM) from the non-minimal gravitational coupling term is not provided. Without an explicit calculation from the Lagrangian (including any cutoff scale or matching procedure), it is unclear whether the three benchmark coupling values simultaneously satisfy the lifetime > age of the universe requirement and produce the claimed observable fluxes.

Authors: We agree that an explicit derivation strengthens the presentation. In the revised manuscript we have added a new subsection (Section 2.2) that starts from the non-minimal term ξ φ² R / 2 in the Jordan-frame Lagrangian, performs the Weyl rescaling to the Einstein frame, derives the effective dimension-5 operator after integrating out the graviton, and computes the partial widths to SM final states. The three benchmark values of the coupling were selected precisely so that the resulting lifetime exceeds the age of the Universe while remaining consistent with the cosmological constraints already stated in the text; the new subsection now shows the explicit lifetime calculation for each benchmark. revision: yes
Referee: [Numerical results and flux calculations] The abstract states that numerical computations demonstrate observability, yet the manuscript supplies no details on the specific tools, DM density profile assumptions for the dSph galaxies, propagation modeling, or validation procedures. This absence prevents verification that the reported fluxes and event rates support the observability conclusion for the benchmark points.

Authors: We acknowledge that the computational details were insufficiently documented. The revised Section 3 now specifies: (i) the numerical tools used (Pythia 8.3 for decay spectra, CLUMPY for J-factor integration, and the publicly available neutrino flux code from the IceCube collaboration for propagation); (ii) the adopted DM density profiles for the 14 dSphs (NFW profiles with parameters taken from the literature compilation of Geringer-Sameth et al. 2015, with a brief discussion of Einasto alternatives); (iii) the propagation modeling (gamma-ray absorption negligible below 10 TeV, neutrino oscillations averaged over astrophysical baselines); and (iv) validation against published fluxes for the same dSphs in the literature. These additions allow direct verification of the observability claims for the benchmark points. revision: yes

Circularity Check

0 steps flagged

No circularity; benchmarks externally constrained and signals computed forward

full rationale

The paper selects three benchmark masses and three coupling values that are stated to be consistent with external cosmological constraints on lifetime, then computes gamma-ray and neutrino fluxes from decay products using standard numerical tools for the Milky Way and dwarf galaxies. No parameter is fitted to the target fluxes themselves, no self-definitional loop appears in the provided abstract or description, and no load-bearing self-citation or ansatz smuggling is evident. The derivation chain is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 1 invented entities

The central claim rests on the postulated scalar singlet with imposed Z2 symmetry and non-minimal gravitational coupling, plus three benchmark masses and couplings selected to match cosmology; these are model assumptions without independent falsifiable evidence provided in the abstract.

free parameters (2)

dark matter mass
Three benchmark values selected to be consistent with cosmological constraints
coupling strength
Three values chosen to satisfy cosmological constraints

axioms (2)

domain assumption Z2 symmetry imposed on the Lagrangian
Ensures the scalar singlet remains stable against rapid decay
ad hoc to paper Decay occurs through non-minimal gravitational coupling
Permits slow decay to Standard Model particles while maintaining long lifetime

invented entities (1)

scalar singlet dark matter no independent evidence
purpose: Long-lived decaying dark matter candidate
Introduced as the particle whose decay produces the fluxes

pith-pipeline@v0.9.0 · 5449 in / 1390 out tokens · 55637 ms · 2026-05-10T00:46:26.264751+00:00 · methodology

discussion (0)

Reference graph

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