REVIEW
Fast radio burst - persistent radio source systems I. A 1.2 GHz search and catalog definition
High Energy Astrophysical Phenomena · Submitted 28 Sep 2026 · Published version · 14 references
Pith's verdict: A solid catalog paper whose durable result is the conservative f_all ≈ 0.06; the inclusive repeater preference at 90% CL is a teaser carried by three unconfirmed candidates, one of which the paper itself places outside its own definition.
T0 · AI review
Why Pith says this
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Referee report
The paper
The paper claims
Persistent radio nebulae surround just 1 in 7 fast radio bursts
The reading
What carries the argument
The machinery is a homogenized catalog of 75 FRBs (25 repeaters, 50 apparent one-offs) with persistent-source luminosities or 95% CL upper limits at 1.2 GHz, built by merging new uGMRT measurements with literature results and scaling all luminosities to 1.2 GHz using a spectral index of $\alpha = -0.27$. The occurrence estimate rests on a binomial model $p(f_x | n_x, k_x)$ applied to the subsample whose limits reach below the $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ threshold, and on a strict distinction between confirmed PRSs (compact at parsec scale via VLBI) and candidates (unresolved at arcsecond scale only). The chance-coincidence probability $P_{\rm cc}$ for each candidate — a Poisson estimate of an unrelated background radio source aligning with the FRB localization region — carries the classification of the four new sources.
Extended reading notes
Core claim
The central claim is that persistent radio sources brighter than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ are uncommon companions to fast radio bursts, with an overall occurrence of $f_{\rm all} = 0.06^{+0.09}_{-0.03}$ for confirmed PRSs only and $f_{\rm all} = 0.14^{+0.22}_{-0.08}$ when candidates are included, both at 95% CL. Four new candidate PRSs were found at arcsecond resolution in the uGMRT campaign: three toward repeaters (S11, S12, S20) and one toward an apparently one-off burst (S13). In the inclusive reading the occurrence is $f_{\rm r} = 0.27^{+0.21}_{-0.14}$ for repeaters versus $f_{\rm nr} = 0.03^{+0.14}_{-0.02}$ for one-offs, a difference the paper calls marginal (90% CL) evidence that PRSs prefer repeaters; in the conservative scenario, where none of the new candidates are considered associated, no such preference survives, with $f_{\rm r} = 0.14^{+0.20}_{-0.09}$ and $f_{\rm nr} \leq 0.12$.
Load-bearing premise
The load-bearing assumption is that the four newly detected compact radio sources really belong to their FRBs, especially S11 and S20, whose chance-coincidence probabilities of roughly 0.996 and 0.822 make them likely to be unrelated background sources; if those associations fail, the inclusive occurrence rate and the marginal repeater preference collapse to the conservative values.
Editorial extensions
If this is right
- Luminous PRSs ($L_\nu \geq 10^{29}$ erg s$^{-1}$ Hz$^{-1}$) are rare, appearing in roughly 6–14% of localized FRBs, so a bright magnetized nebula is not a generic feature of the FRB phenomenon.
- If the inclusive reading holds, repeaters are about nine times more likely than one-offs to host a luminous PRS, pointing toward different environments or evolutionary paths for the two classes.
- The catalog is complete down to the $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ threshold and provides a luminosity-limited sample that anchors a companion test of the $L_\nu$–RM correlation.
- The candidate source toward S20 matches the $\sim 10^{29}$ erg s$^{-1}$ Hz$^{-1}$ PRS luminosity predicted from that burst's large rotation measure, supporting the magnetized-nebula picture if the association is confirmed.
- The four new candidates (S11, S12, S13, S20) are flagged for VLBI follow-up to test whether they are truly compact at parsec scales.
Reading between the lines
- If the marginal repeater preference survives confirmation, it would sharpen the magnetar picture: a persistent nebula and a high burst rate would plausibly share a common youthful engine, whereas one-off bursts would need a different or shorter-lived channel.
- The very high chance-coincidence values for S11 (three compact sources, each with $P_{\rm cc} \approx 0.996$) suggest that poorly localized repeaters will frequently pick up unrelated background radio sources, so the true PRS occurrence may sit closer to the conservative estimate than the inclusive one.
- The deeper upper limits obtained by stacking VLASS epochs imply that the next PRSs found will likely be fainter than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$, so a lower luminosity threshold could reveal a population that the present catalog cannot see.
Original abstract
We present new $1.26$ GHz observations of 24 fast radio bursts (FRBs; 9 repeaters and 11 one-offs), conducted with the upgraded Giant Meter Wave Radio Telescope (uGMRT) at arc-second angular scale resolution, and combined them with literature data to construct an extended sample of 75 sources with either persistent luminosity measurements or upper limits. Our catalog is complete down to a $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ luminosity threshold, which corresponds to the value of the first-discovered PRS, associated with FRB 20121102. We detect compact radio emission in six FRB fields, two of which are previously known PRSs and four are new candidates. The four new candidates are associated with three new repeating FRBs and one apparently one-off source. We computed the PRS occurrence using the whole catalog of 75 FRBs and found that PRSs more luminous than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ are rare. Unless otherwise stated, all uncertainties and upper limits are reported at the $95\%$ confidence level (CL). If we only consider confirmed PRSs, we find an occurrence of $f_{\rm all} = 0.06^{+0.09}_{-0.03}$, while including PRS candidates as well yields $f_{\rm all} = 0.14^{+0.22}_{-0.08}$. We also compute the PRS occurrence in the two classes of FRBs: repeating and non-repeating. In the conservative case, i.e., when none of the new PRS candidates are considered to be associated with their FRBs, we find no preferred association between the PRSs and FRB class, with an occurrence of $f_{\rm r} = 0.14^{+0.20}_{-0.09}$ for the sample of repeating FRBs and $f_{\rm nr} \leq 0.12$ for the sample of one-off sources. In the inclusive case, i.e., when all the new candidates are considered confirmed PRSs, we find $f_{\rm r} = 0.27^{+0.21}_{-0.14}$ and $f_{\rm nr} = 0.03^{+0.14}_{-0.02}$, with marginal ($90\%$ CL) evidence that PRSs are preferably associated with repeating FRBs.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We present new $1.26$ GHz observations of 24 fast radio bursts (FRBs; 9 repeaters and 11 one-offs), conducted with the upgraded Giant Meter Wave Radio Telescope (uGMRT) at arc-second angular scale resolution, and combined them with literature data to construct an extended sample of 75 sources with either persistent luminosity measurements or upper limits. Our catalog is complete down to a $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ luminosity threshold, which corresponds to the value of the first-discovered PRS, associated with FRB 20121102. We detect compact radio emission in six FRB fields, two of which are previously known PRSs and four are new candidates. The four new candidates are associated with three new repeating FRBs and one apparently one-off source. We computed the PRS occurrence using the whole catalog of 75 FRBs and found that PRSs more luminous than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ are rare. Unless otherwise stated, all uncertainties and upper limits are reported at the $95\%$ confidence level (CL). If we only consider confirmed PRSs, we find an occurrence of $f_{\rm all} = 0.06^{+0.09}_{-0.03}$, while including PRS candidates as well yields $f_{\rm all} = 0.14^{+0.22}_{-0.08}$. We also compute the PRS occurrence in the two classes of FRBs: repeating and non-repeating. In the conservative case, i.e., when none of the new PRS candidates are considered to be associated with their FRBs, we find no preferred association between the PRSs and FRB class, with an occurrence of $f_{\rm r} = 0.14^{+0.20}_{-0.09}$ for the sample of repeating FRBs and $f_{\rm nr} \leq 0.12$ for the sample of one-off sources. In the inclusive case, i.e., when all the new candidates are considered confirmed PRSs, we find $f_{\rm r} = 0.27^{+0.21}_{-0.14}$ and $f_{\rm nr} = 0.03^{+0.14}_{-0.02}$, with marginal ($90\%$ CL) evidence that PRSs are preferably associated with repeating FRBs.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We present new $1.26$ GHz observations of 24 fast radio bursts (FRBs; 9 repeaters and 11 one-offs), conducted with the upgraded Giant Meter Wave Radio Telescope (uGMRT) at arc-second angular scale resolution, and combined them with literature data to construct an extended sample of 75 sources with either persistent luminosity measurements or upper limits. | contribution 0.70 | 0.97 | 0.07 | asserted 1.00 |
| s1 | Our catalog is complete down to a $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ luminosity threshold, which corresponds to the value of the first-discovered PRS, associated with FRB 20121102. | contribution 0.47 | 0.58 | 0.06 | asserted 1.00 |
| s2 | We detect compact radio emission in six FRB fields, two of which are previously known PRSs and four are new candidates. | result 1.00 | 0.96 | 0.10 | asserted 1.00 |
| s3 | The four new candidates are associated with three new repeating FRBs and one apparently one-off source. | result 0.99 | 0.90 | 0.06 | asserted 0.99 |
| s4 | We computed the PRS occurrence using the whole catalog of 75 FRBs and found that PRSs more luminous than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ are rare. | result 1.00 | 0.97 | 0.33 | asserted 1.00 |
| s5 | Unless otherwise stated, all uncertainties and upper limits are reported at the $95\%$ confidence level (CL). | method 0.99 | 0.61 | 0.02 | asserted 0.97 |
| s6 | If we only consider confirmed PRSs, we find an occurrence of $f_{\rm all} = 0.06^{+0.09}_{-0.03}$, while including PRS candidates as well yields $f_{\rm all} = 0.14^{+0.22}_{-0.08}$. | result 1.00 | 0.97 | 0.20 | asserted 1.00 |
| s7 | We also compute the PRS occurrence in the two classes of FRBs: repeating and non-repeating. | contribution 0.73 | 0.95 | 0.04 | asserted 0.82 |
| s8 | In the conservative case, i.e., when none of the new PRS candidates are considered to be associated with their FRBs, we find no preferred association between the PRSs and FRB class, with an occurrence of $f_{\rm r} = 0.14^{+0.20}_{-0.09}$ for the sample of repeating FRBs and $f_{\rm nr} \leq 0.12$ for the sample of one-off sources. | result 1.00 | 0.97 | 0.12 | asserted 0.98 |
| s9 | In the inclusive case, i.e., when all the new candidates are considered confirmed PRSs, we find $f_{\rm r} = 0.27^{+0.21}_{-0.14}$ and $f_{\rm nr} = 0.03^{+0.14}_{-0.02}$, with marginal ($90\%$ CL) evidence that PRSs are preferably associated with repeating FRBs. | result 0.96 | 0.97 | 0.34 | asserted 0.72 |
What was examined, and what was not
- arXiv listing abstract v1
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- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
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- C citations
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Figures
Figures reproduced from arXiv:2609.35729 by the authors.
References
Discussion
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