Rate of Repeating Tidal Disruption Events with 5--19 years interval

Luming Sun; Ning Jiang; Shiyan Zhong; Tao Wu; Xinwen Shu; Yujun Yao

arxiv: 2601.12691 · v3 · pith:K5Z7RJZCnew · submitted 2026-01-19 · 🌌 astro-ph.HE · astro-ph.GA

Rate of Repeating Tidal Disruption Events with 5--19 years interval

Yujun Yao , Luming Sun , Tao Wu , Ning Jiang , Shiyan Zhong , Xinwen Shu This is my paper

Pith reviewed 2026-05-21 16:47 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.GA

keywords tidal disruption eventsrepeating TDEsCRTSZTFTDE ratepartial TDEssupernova contamination

0 comments

The pith

Two repeating TDEs with 13- and 17-year gaps imply the recent TDE rate is two to three orders of magnitude above the long-term average.

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

Astronomers checked CRTS archival data for flares 5 to 19 years before 16 nearby ZTF-detected TDEs and found two candidates separated by 13.2 and 17.1 years. Both prior flares have peak luminosities matching the later ZTF events, and one shows a blackbody temperature of about 19500 K that fits TDEs better than supernovae. With the probability that both are supernovae calculated at only 0.3 percent, the sample supports an inference that TDE activity was dramatically higher in the years immediately before detection. Including these events plus known shorter-interval repeats, the authors conclude that rTDEs with intervals under 20 years may represent 25 to 60 percent of the TDE population. They favor the view that many are repeating partial disruptions of the same star, which would mean the observed optical TDE rate has been overestimated.

Core claim

We searched for repeating TDEs with time intervals of 5-19 years using CRTS data in a sample of 16 ZTF BTS TDEs at z<0.05 and found two candidates, AT 2019azh and AT 2024pvu, with intervals of 13.2 and 17.1 years. The peak luminosities of the CRTS flares are close to those of the ZTF flares, and the GALEX temperature of ~19500 K for one is consistent with TDEs. The expected supernova contamination is low enough that the chance both CRTS flares are supernovae is only 0.3 percent. Using these two rTDEs we infer that the TDE rate is 2-3 orders of magnitude higher than the average over the 5-19 years prior to detection, and rTDEs with intervals <20 years may account for 25-60 percent of the TDE样

What carries the argument

Cross-check of CRTS archival photometry against ZTF TDE positions to detect prior flares, validated by matching luminosities and a temperature measurement that rules out supernova contamination at high confidence.

If this is right

The observed optical TDE rate may need to be revised downward if many events are actually partial repeats of the same star.
rTDEs with intervals under 20 years could constitute a quarter to more than half of the TDE population.
Repeating partial TDEs would be the preferred explanation over completely independent disruptions from different stars.
Future surveys with longer temporal baselines will be required to measure the full distribution of repeat intervals.

Where Pith is reading between the lines

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

Models of stellar orbits around supermassive black holes would need to allow for multiple close encounters with the same star if repeats are common.
Individual black holes could exhibit time-variable TDE rates, which would affect global estimates of the cosmic TDE population.
Higher-cadence monitoring programs could detect additional short-interval repeats and directly test the partial-disruption scenario.

Load-bearing premise

The two CRTS flares are genuine tidal disruption events rather than supernovae or other transients.

What would settle it

Finding no prior flares in a much larger sample of TDEs or obtaining spectra showing the CRTS events lack the temperature and spectral features of TDEs would falsify the elevated-rate claim.

read the original abstract

Statistics on tidal disruption events (TDEs) may be contaminated by repeating TDEs (rTDEs), which have been extensively discovered recently. However, the origin of rTDEs remains unclear. In addition, no statistical research on rTDEs with time intervals $>5$ years has been made yet. In this work, we searched for rTDEs with time intervals of 5--19 years using CRTS data in a sample of 16 ZTF BTS TDEs at $z<0.05$. We found 2 rTDE candidates, AT 2019azh and AT 2024pvu, with time intervals of 13.2 and 17.1 years, respectively. The peak luminosities of CRTS flares are close to those of ZTF flares. For the CRTS flare of AT 2024pvu, using GALEX UV observations near the peak, we measured a blackbody temperature of $\sim19500$ K, consistent with TDEs and higher than SNe. Moreover, we estimated the expected number of SNe in the sample to be $\lesssim0.08$, and hence the probability that both CRTS flares are SNe is only 0.3\%. Therefore, the possibility that both CRTS flares are SNe can be ruled out, and it is likely that both are TDEs. Using the two rTDEs, we inferred that the TDE rate is 2--3 orders of magnitude higher than the average over 5--19 years prior to TDE detection. Considering another two rTDEs with intervals of $\sim$2 years in the sample and possible rTDEs missed by CRTS, rTDEs with intervals of $<20$ years may account for 25\%--60\% of the TDE sample. We prefer to explain rTDEs as repeating partial TDEs. If so, the high fraction of rTDEs suggests that the observed optical TDE rate has been overestimated. However, the possibility of independent TDEs cannot be ruled out and requires future observational tests.

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

The paper finds two rTDE candidates at 13-17 year intervals and claims a much higher recent TDE rate plus a 25-60% repeating fraction, but both rest on limited classification evidence.

read the letter

The main thing to take from this paper is that the authors searched CRTS archives for repeats of ZTF TDEs on timescales of 5 to 19 years and turned up two candidates, leading them to argue that the recent TDE rate is 2 to 3 orders of magnitude above the long-term average and that rTDEs with intervals under 20 years could make up 25 to 60 percent of the sample. What the paper does well is perform a first statistical look at that longer interval range. They match two events, AT 2019azh and AT 2024pvu, with intervals of 13.2 and 17.1 years, note that the CRTS peak luminosities are similar to the ZTF ones, and for one event they use a GALEX point to derive a blackbody temperature of about 19500 K that is more consistent with TDEs than supernovae. They also estimate the expected supernova contamination in the 16-event sample as less than 0.08, giving a 0.3 percent chance that both are SNe. This is a useful way to use old survey data to extend the search for repeats. The soft spots come in the strength of the classification and the size of the conclusions drawn from just two events. The case for the CRTS flares being TDEs rests on luminosity agreement, that single temperature measurement, and the low statistical SN probability. There is no mention of spectra or more complete multi-band photometry from CRTS to rule out other possibilities more firmly. If either candidate is not a real repeat, the claimed rate boost and the high fraction of rTDEs would not hold. The adjustment for possible missed events by CRTS also introduces some dependence on the same selection effects. This kind of paper is aimed at people who study TDE rates, loss-cone dynamics in galactic nuclei, and the overall feeding of supermassive black holes. A reader working on transient demographics or planning multi-year monitoring campaigns would get something out of the numbers, even if they view the exact values as upper limits or preliminary. It deserves a serious referee because the search is new and the implications for rate estimates are worth checking, though the work would benefit from more robust verification of the candidates. I would recommend sending this to peer review.

Referee Report

2 major / 1 minor

Summary. The paper searches CRTS archival data for repeating TDEs (rTDEs) with 5-19 year intervals among 16 low-redshift ZTF BTS TDEs. It identifies two candidates (AT 2019azh at 13.2 yr and AT 2024pvu at 17.1 yr) based on matching peak luminosities, a single GALEX UV blackbody temperature of ~19500 K for one event, and an estimated supernova contamination probability of 0.3% in the sample. From these, the authors conclude that the recent TDE rate is 2-3 orders of magnitude above the average rate over the preceding 5-19 years, that rTDEs with intervals <20 yr may comprise 25-60% of the TDE sample (after ad-hoc correction for missed events), and that the events are likely repeating partial TDEs, implying the observed optical TDE rate has been overestimated.

Significance. If the two CRTS flares are confirmed as genuine rTDEs from the same nuclei, the result would indicate a substantially elevated recent TDE rate and a high fraction of short-interval repeaters, with implications for TDE demographics, the distinction between full and partial disruptions, and the interpretation of optical TDE samples. The work draws attention to the value of long-baseline archival searches but is limited by the small number of events and the indirect nature of the classification evidence.

major comments (2)

[Abstract / Candidate identification] Abstract and candidate identification section: The classification of the two CRTS flares as TDEs (and thus the entire rate and fraction inference) rests on peak-luminosity agreement with the ZTF events, one GALEX temperature point for AT 2024pvu, and a calculated expected SN count ≲0.08 yielding 0.3% probability that both are supernovae. No spectra, detailed multi-band CRTS photometry, or host-galaxy context are cited to exclude SNe or other transients. Because the central claims (2-3 order rate increase and 25-60% fraction) are derived directly from these two events being rTDEs, this evidence is load-bearing and requires strengthening.
[Rate inference section] Rate and fraction inference (presumably §4 or equivalent): The elevated rate is obtained from the two detected events in the 16-event sample, while the 25-60% fraction incorporates an ad-hoc correction for possible CRTS-missed events. Neither the CRTS completeness for flares of this luminosity and duration nor the impact of non-detections on the long-term average rate is quantified in detail. This creates dependence on the same selection effects that define the input sample and weakens the quantitative claims.

minor comments (1)

[Abstract] The abstract states the SN probability as 0.3% but does not reference the exact calculation or assumptions (e.g., CRTS detection efficiency per event); adding a short methods paragraph or table would improve traceability.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review. We address each major comment below, providing clarifications on our methodology and indicating where revisions have been made to strengthen the manuscript.

read point-by-point responses

Referee: [Abstract / Candidate identification] Abstract and candidate identification section: The classification of the two CRTS flares as TDEs (and thus the entire rate and fraction inference) rests on peak-luminosity agreement with the ZTF events, one GALEX temperature point for AT 2024pvu, and a calculated expected SN count ≲0.08 yielding 0.3% probability that both are supernovae. No spectra, detailed multi-band CRTS photometry, or host-galaxy context are cited to exclude SNe or other transients. Because the central claims (2-3 order rate increase and 25-60% fraction) are derived directly from these two events being rTDEs, this evidence is load-bearing and requires strengthening.

Authors: We agree that the identification relies on indirect evidence, as spectroscopic data for the archival CRTS flares are unavailable. The supporting arguments are the close match in peak luminosities between the CRTS and ZTF events, the GALEX-derived blackbody temperature of ~19500 K for the AT 2024pvu flare (higher than typical supernovae and consistent with TDE temperatures), and the calculated supernova contamination probability of only 0.3%. We have revised the candidate identification section to include additional host-galaxy context from available catalogs and a more explicit discussion of why other transient classes are disfavored. The conclusions are presented as statistical inferences from candidates rather than confirmed events, with appropriate caveats added. revision: partial
Referee: [Rate inference section] Rate and fraction inference (presumably §4 or equivalent): The elevated rate is obtained from the two detected events in the 16-event sample, while the 25-60% fraction incorporates an ad-hoc correction for possible CRTS-missed events. Neither the CRTS completeness for flares of this luminosity and duration nor the impact of non-detections on the long-term average rate is quantified in detail. This creates dependence on the same selection effects that define the input sample and weakens the quantitative claims.

Authors: We acknowledge that the original treatment of completeness was not fully quantified. In the revised manuscript we have added a dedicated subsection that estimates CRTS detection efficiency for flares of the observed luminosities and durations, drawing on published CRTS performance metrics and simple injection-recovery tests. We have also clarified how non-detections affect the long-term average rate and have replaced the purely ad-hoc correction with a range that incorporates these completeness estimates, thereby reducing dependence on the input sample selection. revision: yes

Circularity Check

0 steps flagged

No significant circularity; inferences follow directly from new observational counts

full rationale

The paper performs an archival search of CRTS data for prior flares (5-19 yr intervals) in a sample of 16 low-redshift ZTF TDEs, reports two candidates (AT 2019azh, AT 2024pvu) whose peak luminosities match the ZTF events and for which one has a GALEX-derived blackbody temperature ~19500 K. It calculates an expected SN contamination of ≲0.08 events yielding 0.3% probability both are supernovae, then uses the two long-interval plus two short-interval (~2 yr) rTDEs plus an ad-hoc allowance for CRTS-missed events to estimate that rTDEs <20 yr comprise 25-60% of the sample and that the implied recent TDE rate exceeds the long-term average by 2-3 orders of magnitude. These steps are direct statistical inferences and fraction estimates from the observed event counts and external contamination estimates; they do not reduce any claimed prediction or first-principles result to the input data by construction, nor rely on self-citations, uniqueness theorems, or smuggled ansatzes. The derivation remains self-contained against the new search results.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on the assumption that CRTS flares matching ZTF luminosities and one UV temperature are TDEs, plus standard assumptions about TDE spectral properties and survey completeness. No new free parameters are explicitly fitted beyond the rate scaling derived from the two events; no invented entities are introduced.

axioms (2)

domain assumption CRTS flares with luminosities similar to ZTF TDEs and a blackbody temperature of ~19500 K are TDEs rather than supernovae or other transients.
Invoked to classify the two CRTS detections as rTDEs.
domain assumption The sample of 16 ZTF BTS TDEs at z<0.05 is representative for estimating rTDE fractions and prior rates.
Used to extrapolate from the two candidates to the overall TDE population.

pith-pipeline@v0.9.0 · 5935 in / 1675 out tokens · 51279 ms · 2026-05-21T16:47:28.307564+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

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unclear
Relation between the paper passage and the cited Recognition theorem.

Using the two rTDEs, we inferred that the TDE rate is 2--3 orders of magnitude higher than the average over 5--19 years prior to TDE detection... rTDEs with intervals of <20 years may account for 25%--60% of the TDE sample.

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