Limits to star formation in post starburst galaxies from Type II supernovae

Laetile Makoko Roberto De Propris

REVIEW 4 major objections 5 minor 19 references

Limits to star formation in post starburst galaxies from Type II supernovae

T0 review · 4 major / 5 minor · reviewed 2026-08-15 · deepseek-v4-flash

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Pith's one-line read No Type II supernovae appear in 311 nearby post-starburst galaxies over seven years, yielding a 95% upper limit of 0.8 solar masses per year on current star formation and the conclusion that star formation has stopped.

desk verdict A sensible zero-detection SFR limit that is probably too strong because the assumed survey exposure time and the conversion details are not justified. read the letter →

arxiv 2506.15178 v1 pith:O6SEU4SP submitted 2025-06-18 astro-ph.GA

Laetile Makoko Roberto De Propris This is my paper · ORCID

classification astro-ph.GA

keywords post-starburstgalaxiesTypeIIsupernovaestarformationratesgalaxyquenchingsupernovagreenvalleynulldetection

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

Post-starburst galaxies are galaxies whose optical spectra are dominated by A-type stars, a sign that a recent burst of star formation was abruptly halted roughly a billion years ago. This paper asks whether any star formation is still happening in them, using Type II supernovae—explosions of stars heavier than about eight solar masses—as a tracer of star formation over the last 50 million years. The authors search the seven-year Zwicky Transient Facility Bright Transient Survey for supernovae inside the standard Petrosian radii of 311 nearby post-starburst galaxies and find none. From zero detections they derive a 95% confidence upper limit of $0.8\,M_\odot\,{\rm yr}^{-1}$ on the current star formation rate in the optically selected sample and $0.3\,M_\odot\,{\rm yr}^{-1}$ in the younger 'shocked' sample, concluding that star formation in these galaxies has completely ceased. This sharpens the earlier radio-based limit and matters because these galaxies often contain large gas reservoirs that, in principle, could still fuel star formation.

What carries the argument

The central machinery is the Type II supernova rate used as a star-formation clock. Type II supernovae are the explosions of stars with initial masses greater than about $8\,M_\odot$, and they occur within roughly 50 million years of their formation, so their occurrence rate traces recent star formation. The paper counts supernovae inside each galaxy's Petrosian radius (the standard aperture defined by SDSS photometry) using the Bright Transient Survey, which spectroscopically classifies all transients and is complete for Type II supernovae to $z=0.05$. With zero events in $N$ galaxies over a $T=7$ year baseline, the binomial distribution supplies the 95% upper limit on the supernova fraction, and the conversion ${\rm SN}_{\rm CC}=k\times{\rm SFH}$, with $k=0.0070\,M_\odot^{-1}$ derived from the Salpeter mass function, turns that count into a star-formation-rate limit. A rate-size slope of $-0.25$ is adopted to express the same null result as a volumetric supernova rate.

What would settle it

A spectroscopically confirmed Type II supernova whose position and redshift match any galaxy in either of the two post-starburst samples, with an explosion date inside the seven-year survey window, would overturn the zero-detection result; recomputing the limit with the actual per-galaxy exposure time would test whether the 0.8 solar-mass-per-year bound is secure.

Watch

Extended reading notes

Core claim

On the paper's own terms, the discovery is a null detection with teeth: in 65 galaxies from the optically selected sample and 246 galaxies from the younger shock-selected sample, no Type II supernova is found within the Petrosian radius over the seven-year survey, which is complete for these supernovae to $z<0.05$. Treating the counts with the binomial distribution gives a 95% upper limit to the supernova fraction of 0.04 and 0.01 for the two samples. Converting through the relation ${\rm SN}_{\rm CC}=k\times{\rm SFH}$ with $k=0.0070\,M_\odot^{-1}$ (from a Salpeter initial mass function) yields ${\rm SFR}<0.8\,M_\odot\,{\rm yr}^{-1}$ and ${\rm SFR}<0.3\,M_\odot\,{\rm yr}^{-1}$ respectively. The authors conclude that star formation in post-starburst galaxies has completely ceased, that the limits agree with the 1.4 GHz stacked upper limit of $1.6\,M_\odot\,{\rm yr}^{-1}$, and that any residual radio emission is more likely from weak active galactic nuclei than from ongoing star formation.

Load-bearing premise

The argument assumes the seven-year sky survey caught every exploding massive star in these galaxies; if some were missed because they were too faint, dust-hidden, outside the chosen aperture, or observed for less than seven years, the true star-formation limit would be weaker.

Editorial extensions

If this is right

The current star formation rate in the optically selected post-starburst sample is below $0.8\,M_\odot\,{\rm yr}^{-1}$ at 95% confidence, and below $0.3\,M_\odot\,{\rm yr}^{-1}$ in the younger shock-selected sample.
Despite the molecular gas reservoirs previously found in many post-starburst galaxies, these galaxies are not forming massive stars at an observable rate, so the gas is not being converted into stars in any simple way.
The new limits agree with and sharpen the earlier 1.4 GHz radio upper limit, ruling out star formation as the main source of the residual radio emission in favor of weak active galactic nuclei.
The upper limits are comparable to those for elliptical galaxies, placing post-starburst galaxies among the most quiescent galaxy populations at low redshift.

Reading between the lines

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

A natural extension the paper does not pursue is to stack all 311 galaxies together, which would push the combined zero-count limit lower and could distinguish 'fully quenched' from 'still forming stars at a rate of a few hundredths of a solar mass per year.'
Because Type II supernovae trace only stars above about eight solar masses, the result leaves open the possibility of very low-level star formation producing only low-mass stars; deep ultraviolet imaging or nebular-line stacking would test that separately.
The same method could be applied to other green-valley populations or to a time-resolved sample of post-starburst galaxies of different ages, mapping how quickly star formation shuts off after a burst.

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Editorial analysis

A structured set of objections, weighed in public.

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

Desk Editor's Note

read the letter

This is a short RNAAS note with a zero-detection argument: no Type II SNe in 65 + 246 local post-starburst galaxies, giving a 95% upper limit on SFR of <0.8 and <0.3 M_sun/yr. The idea is sound, and the limit is genuinely tighter than the old radio stack limit of <1.6 from Nielsen et al. (2012). The paper deserves credit for using a fresh tracer and for putting a number on quiescence.

What is new is narrow: applying the ZTF BTS completeness to these two PSG samples. The binomial limit itself is standard, and the result is only as good as the assumptions. My main concern is the effective exposure time. The paper uses T=7 years (the BTS duration) for every galaxy, but BTS is a rolling survey with weather, cadence, and footprint gaps. A Type II SN is bright for only weeks. If each galaxy is actually monitored with a duty cycle of 50%, the limit roughly doubles to ~1.6 M_sun/yr, which is the same as the old radio limit; at 20% it becomes ~4 M_sun/yr and the conclusion collapses. No visibility/control-time calculation is given, and no galaxy positions or cross-match details are shown. This is a load-bearing assumption, not a nitpick.

There are also transparency gaps. The SNuM formula in Section 3 is garbled and undefined; I could not reproduce how '<0.008' and '=<0.0004' were obtained. The steps from the binomial fraction to the volumetric SFR and the per-galaxy SFR are not shown. The samples are not demonstrated to lie entirely at z<0.05, where BTS completeness is claimed. Finally, 'completely ceased' is too strong for an upper limit of 0.8 M_sun/yr; it is low, but not zero.

Were these fixed, the paper would be a useful addition to the quenching literature. As is, the central number is not yet trustworthy. For a research note, the omissions are too large. I would not reject the idea. I would send it to a referee who knows BTS completeness, and ask the authors to add a control-time estimate, show the conversion arithmetic, justify the redshift range, and soften the claim.

Referee Report

4 major / 5 minor

Summary. The paper reports the absence of Type II supernovae in two samples of post-starburst galaxies (65 galaxies from Melnick & De Propris 2013 and 246 from Alatalo et al. 2016) using the Zwicky Transient Facility Bright Transient Survey over a nominal 7-year baseline. From the zero detections, the authors derive binomial 95% upper limits on the supernova fraction and then convert these into upper limits on the current star formation rate, quoting SFR < 0.8 M_sun/yr for the Melnick & De Propris sample and < 0.3 M_sun/yr for the Alatalo et al. sample. They conclude that star formation in these galaxies has completely ceased, consistent with earlier radio limits. The paper is a short RNAAS-style research note.

Significance. The method is conceptually attractive: a non-detection of core-collapse supernovae directly probes recent massive-star formation, complementing radio and emission-line limits. The zero-event counts and binomial upper limits are simple and would be credible if the survey completeness and exposure-time assumptions are valid. However, as written, the manuscript does not establish those assumptions, and the conversion from the binomial limit to the quoted SFR is not shown. If the missing technical steps are supplied and the assumptions are validated, the result would be a useful independent constraint on residual star formation in post-starburst galaxies. The paper also benefits from comparing to existing literature (Nielsen et al. 2012; Ma et al. 2025), which provides context, but the current presentation leaves the central quantitative claim unsupported.

major comments (4)

[Section 3, binomial-to-SFR conversion] The derivation from the binomial upper limits (0.04 and 0.01) to the quoted volumetric star formation rate densities (< 0.06 and < 0.02 M_sun yr^-1 Mpc^-3) and then to per-galaxy SFR limits (< 0.8 and < 0.3 M_sun yr^-1) is not shown. The text gives no galaxy stellar masses, no survey volume, no selection function, and no equation linking the supernova fraction to the SFR. Without these details, the headline numbers are not reproducible and the conclusion cannot be verified. This is a load-bearing gap because the abstract's central claim depends on this conversion.
[Section 2, completeness and exposure time] The assumption that the ZTF Bright Transient Survey provides 7 years of complete monitoring for every galaxy in both samples is not justified. The cited completeness of BTS to z = 0.05 (Fremling et al. 2020, Fig. 4) refers to spectroscopic classification of discovered transients, not to continuous temporal coverage of any particular galaxy. The manuscript does not demonstrate that all galaxies in the Melnick & De Propris and Alatalo et al. samples lie at z < 0.05, nor does it provide the effective ZTF control time per galaxy. With realistic cadence gaps, the effective exposure is shorter than 7 years; for example, a 50% duty cycle would roughly double the quoted SFR limit to ~1.6 M_sun/yr, comparable to the radio limit, and a 20% duty cycle would raise it to ~4 M_sun/yr, which would no longer support the claim that star formation has completely ceased.
[Section 3, SNuM formula] The formula 'SNuM(M0) = N / T * M_RSS * 1 / 0 * sum_i M_i^(RSSM+1)' is garbled and undefined. The quantity RSSM is not defined in the formula, the summation index and range are unclear, and the units printed immediately after the formula ('SN(100 yr^-1 (10^10 M_sun)^-1)') are mangled. As written, the expression cannot be checked or applied, so the two quoted SNuM upper limits (< 0.008 and < 0.0004) are unsupported. The authors should provide the correct equation, with all variables defined, or cite the exact numbered equation from Ma et al. (2025).
[Section 3, conclusion] The statement that 'star formation in these objects has completely ceased' is stronger than the analysis justifies. A 95% upper limit of 0.8 M_sun/yr is an upper bound, not a measurement of zero star formation; it is consistent with low-level ongoing star formation. The manuscript also does not propagate systematic uncertainties in the IMF normalization, the assumed supernova rate per unit star formation, or the completeness corrections. The conclusion should be softened to state that the current star formation rate is constrained to be very low, unless additional evidence is provided to rule out values below the quoted limit.

minor comments (5)

[Section 3, text after the SFR limits] The sentence beginning 'respectively. which is in good agreement' has a lowercase 'which' after a period; it should be 'This is in good agreement' or similar.
[Section 3, SNuM upper limit formatting] The line 'SNuM(M0) =< 0.0004 Alatalo et al . 2016' contains a typographical error: it should read 'SNuM(M0) < 0.0004' to be consistent with the other limit.
[Section 3, IMF conversion factor] The constant k = 0.0070 M_sun^-1 in the equation after 'SNR_CC = k * SFH' is stated without derivation or citation; while the Salpeter IMF is mentioned, the reader cannot easily verify the normalization or the mass limits. A brief explanation or reference to a standard calculation would help.
[Section 2, sample properties] The manuscript does not state the redshift distribution, stellar mass range, or volume spanned by the two samples. At minimum, the mean redshift and mean stellar mass should be reported, since these enter the volumetric rate conversion and the comparison with the Ma et al. (2025) rates.
[Figure 1 caption] The figure caption is incomplete in the manuscript text: it ends with 'Error bars from X. Ma et al. (2025) are omitted.' without a full sentence describing the plotted points and limits. The caption should be self-contained for the reader.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the SFR limit is derived from independent ZTF BTS SN counts and standard conversions; self-citations are data/context, not load-bearing.

full rationale

The paper derives a 95% upper limit to the star formation rate in post-starburst galaxies from the absence of Type II supernovae in ZTF BTS. The derivation chain is: (1) select galaxy samples from Melnick & De Propris (2013) and Alatalo et al. (2016), which are published datasets rather than fitted parameters; (2) count zero SNe within Petrosian radii; (3) apply the binomial distribution to obtain upper limits on the SN fraction; (4) convert to supernova rates using the Ma et al. (2025) expression, with the IMF normalization k computed from the Salpeter IMF and the rate-size slope RSSM adopted from Li et al. (2011). None of these steps reduces to the target result by construction: the SFR limit is a function of the observed zero count, the survey duration, and external calibrations. The authors' self-citations (their own PSG sample and the earlier radio limit) are used as data and comparison, not as the source of the SN-based limit. The survey completeness and 7-year baseline are assumptions but are not circular—they are empirical conditions that could be challenged, but they do not make the derivation equivalent to its inputs. The conclusion that star formation has ceased is a physical interpretation of an independent observational tracer, not a restatement of the sample definition. Overall, no circular step is present.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

The paper relies on several adopted conversions and survey assumptions rather than fitting parameters to data. No new physical entities are introduced.

assumptions (4)

domain assumption Type II supernovae trace recent star formation with conversion k = 0.0070 M_sun^-1, derived for a Salpeter IMF with 8-50 M_sun progenitors.
Used in Section 3 to convert the supernova upper limit into a star formation rate; the conversion depends on the assumed IMF and progenitor mass range.
domain assumption The ZTF BTS survey is complete for Type II supernovae to at least z=0.05 over its full duration.
Invoked in Section 2 to justify that zero detections means zero supernovae in the samples; completeness is claimed from Fremling et al. (2020) but is not quantified per galaxy.
domain assumption All sample galaxies are at z < 0.05 and lie within the ZTF footprint, and the SDSS Petrosian radius is the correct search aperture.
The abstract states z<0.05 but the samples are not shown to satisfy this cut; using Petrosian radii may exclude supernovae in the outer galaxy.
domain assumption The rate-size slope RSSM = -0.25 from Li et al. (2011) applies to the post-starburst samples for the SNuM calculation.
Adopted in Section 3 for the SNuM(M0) normalization; it is measured for a different galaxy population.

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Cite this review

Pith. "Pith review of Limits to star formation in post starburst galaxies from Type II supernovae." pith.science (2026). https://pith.science/paper/O6SEU4SP

@misc{pith2026250615178,
  author       = {Pith},
  title        = {Pith review of: Limits to star formation in post starburst galaxies from Type II supernovae},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/O6SEU4SP}},
  note         = {Machine review of arXiv:2506.15178}
}

abstract

We establish significant upper limits to the current star formation rate in two samples of post starburst galaxies by measuring the rate of Type II supernovae from the Zwicky Transient Factory Bright Transient Survey. No Type II supernovae are observed within the Petrosian radii of $z < 0.05$ post starburst galaxies during this supernova search survey. We calculate that at 95\% confidence level the star formation rate in these galaxies is $< 0.8$ M$_{\odot}$ yr$^{-1}$.

Figures

Figures reproduced from arXiv: 2506.15178 by the authors.

**Figure 1.** Volumetric supernova rates from X. Ma et al. (2025) and our results vs. Hubble type. Upper limits are indicated by the downward facing arrows and identified in the figure (to the left of each arrow). Error bars from X. Ma et al. (2025) are omitted. in units of SN(100 yr−1 (1010 M⊙) −1 ) In [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗

Review history (2 revisions) →

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Works this paper leans on

19 extracted references · 3 canonical work pages

[1]

2022, ApJS, 259, 35, doi: 10.3847/1538-4365/ac4414

Abdurro’uf, Accetta, K., Aerts, C., et al. 2022, ApJS, 259, 35, doi: 10.3847/1538-4365/ac4414

doi:10.3847/1538-4365/ac4414 2022
[2]

L., Rich, J

Alatalo, K., Cales, S. L., Rich, J. A., et al. 2016, ApJS, 224, 38, doi: 10.3847/0067-0049/224/2/38 3

doi:10.3847/0067-0049/224/2/38 2016
[3]

D., et al

Baron, D., Netzer, H., French, K. D., et al. 2023, MNRAS, 524, 2741, doi: 10.1093/mnras/stad1792

doi:10.1093/mnras/stad1792 2023
[4]

S., Suess, K

Bezanson, R., Spilker, J. S., Suess, K. A., et al. 2022, ApJ, 925, 153, doi: 10.3847/1538-4357/ac3dfa

doi:10.3847/1538-4357/ac3dfa 2022
[5]

L., Huang, Q., Yang, D., et al

Ellison, S. L., Huang, Q., Yang, D., et al. 2025, arXiv e-prints, arXiv:2503.03066, doi: 10.48550/arXiv.2503.03066

arXiv doi:10.48550/arxiv.2503.03066 2025
[6]

A., Sharma, Y., et al

Fremling, C., Miller, A. A., Sharma, Y., et al. 2020, ApJ, 895, 32, doi: 10.3847/1538-4357/ab8943

doi:10.3847/1538-4357/ab8943 2020
[7]

2007, MNRAS, 381, 187, doi: 10.1111/j.1365-2966.2007.12227.x

Goto, T. 2007, MNRAS, 381, 187, doi: 10.1111/j.1365-2966.2007.12227.x

arXiv 2007
[8]

J., Schulze, S., et al

Irani, I., Prentice, S. J., Schulze, S., et al. 2022, ApJ, 927, 10, doi: 10.3847/1538-4357/ac4709

doi:10.3847/1538-4357/ac4709 2022

Show all 19 references

[10]

J., et al

Li, X., Li, C., Mo, H. J., et al. 2024, ApJ, 963, 86, doi: 10.3847/1538-4357/ad1ce3

2024 doi
[11]

2025, arXiv e-prints, arXiv:2504.04507, doi: 10.48550/arXiv.2504.04507

Ma, X., Wang, X., Mo, J., et al. 2025, arXiv e-prints, arXiv:2504.04507, doi: 10.48550/arXiv.2504.04507

2025 doi arXiv
[12]

2013, MNRAS, 431, 2034, doi: 10.1093/mnras/stt199

Melnick, J., & De Propris, R. 2013, MNRAS, 431, 2034, doi: 10.1093/mnras/stt199

2013 doi
[13]

M., Ridgway, S

Nielsen, D. M., Ridgway, S. E., De Propris, R., & Goto, T. 2012, ApJL, 761, L16, doi: 10.1088/2041-8205/761/2/L16 Planck Collaboration, Aghanim, N., Akrami, Y., et al. 2020, A&A, 641, A6, doi: 10.1051/0004-6361/201833910

2012 doi
[14]

M., & Wu, H

Poggianti, B. M., & Wu, H. 2000, ApJ, 529, 157, doi: 10.1086/308243

2000 doi
[15]

T., French, K

Smercina, A., Smith, J.-D. T., French, K. D., et al. 2022, ApJ, 929, 154, doi: 10.3847/1538-4357/ac5d5f

2022 doi
[16]

2011,, Astrophysics Source Code Library, record ascl:1101.010

Taylor, M. 2011,, Astrophysics Source Code Library, record ascl:1101.010

2011
[17]

2020, MNRAS, 494, 529, doi: 10.1093/mnras/staa674

Wild, V., Taj Aldeen, L., Carnall, A., et al. 2020, MNRAS, 494, 529, doi: 10.1093/mnras/staa674

2020 doi
[18]

I., Schawinski, K., Kaviraj, S., et al

Wong, O. I., Schawinski, K., Kaviraj, S., et al. 2012, MNRAS, 420, 1684, doi: 10.1111/j.1365-2966.2011.20159.x

2012
[19]

M., & Ho, L

Yesuf, H. M., & Ho, L. C. 2020, ApJ, 900, 107, doi: 10.3847/1538-4357/abaa43

2020 doi
[20]

G., Adelman, J., Anderson, Jr., J

York, D. G., Adelman, J., Anderson, Jr., J. E., et al. 2000, AJ, 120, 1579, doi: 10.1086/301513

2000 doi

Pith tools

Reviewed August 15, 2026 · model on record in the stance chip above.

[1] [1]

2022, ApJS, 259, 35, doi: 10.3847/1538-4365/ac4414

Abdurro’uf, Accetta, K., Aerts, C., et al. 2022, ApJS, 259, 35, doi: 10.3847/1538-4365/ac4414

doi:10.3847/1538-4365/ac4414 2022

[2] [2]

L., Rich, J

Alatalo, K., Cales, S. L., Rich, J. A., et al. 2016, ApJS, 224, 38, doi: 10.3847/0067-0049/224/2/38 3

doi:10.3847/0067-0049/224/2/38 2016

[3] [3]

D., et al

Baron, D., Netzer, H., French, K. D., et al. 2023, MNRAS, 524, 2741, doi: 10.1093/mnras/stad1792

doi:10.1093/mnras/stad1792 2023

[4] [4]

S., Suess, K

Bezanson, R., Spilker, J. S., Suess, K. A., et al. 2022, ApJ, 925, 153, doi: 10.3847/1538-4357/ac3dfa

doi:10.3847/1538-4357/ac3dfa 2022

[5] [5]

L., Huang, Q., Yang, D., et al

Ellison, S. L., Huang, Q., Yang, D., et al. 2025, arXiv e-prints, arXiv:2503.03066, doi: 10.48550/arXiv.2503.03066

arXiv doi:10.48550/arxiv.2503.03066 2025

[6] [6]

A., Sharma, Y., et al

Fremling, C., Miller, A. A., Sharma, Y., et al. 2020, ApJ, 895, 32, doi: 10.3847/1538-4357/ab8943

doi:10.3847/1538-4357/ab8943 2020

[7] [7]

2007, MNRAS, 381, 187, doi: 10.1111/j.1365-2966.2007.12227.x

Goto, T. 2007, MNRAS, 381, 187, doi: 10.1111/j.1365-2966.2007.12227.x

arXiv 2007

[8] [8]

J., Schulze, S., et al

Irani, I., Prentice, S. J., Schulze, S., et al. 2022, ApJ, 927, 10, doi: 10.3847/1538-4357/ac4709

doi:10.3847/1538-4357/ac4709 2022