{"id":"48837673-7709-4633-ad36-1a516b4ea916","arxiv_id":"2412.20050","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"New 1250 MHz observations of four magnetars and PSR J1846-0258 with FAST detect no radio emission, yielding periodic flux upper limits of about 8 to 17 microJy.","lead":"Astronomers searched four magnetars and one magnetar-like pulsar with the FAST radio telescope at 1250 MHz, detecting no periodic pulses or single bursts. The non-detections set the deepest radio flux limits yet for these sources, sharpening the puzzle of why most magnetars stay radio-quiet.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Section 3.1 lists spin periods that do not match Table 1; if the Section 3.1 values were used in prepfold, the periodic search would be insensitive and the quoted upper limits invalid.","rationale":"The strongest claim of the paper is the quantitative upper limit S1250 <= 16.9 uJy for periodic emission. This limit is derived from a prepfold search at the known spin period, so the period used is load-bearing. The manuscript contains two contradictory sets of periods. In Section 3.1, the 'extrapolated spin periods at the start of our radio observations' are given as 5.759819, 2.479967, 11.77364, and 5.1579 s, while Table 1 lists 5.7620695, 2.4823018, 11.788978, and 5.19987 s. For SGR 1900+14 the difference is 0.042 s, which over 2100 s produces a phase drift of about 17 s, completely washing out a 10% duty-cycle pulse. If the Section 3.1 values were actually used in prepfold, the non-detection is uninformative and the quoted limits are not valid. If the Table 1 values were used, the text contains a serious typo, but the science is fine. Either way, the paper as submitted does not allow a reader to determine which is correct, making the central quantitative claim irreproducible. This is a more fundamental issue than the duty-cycle/red-noise correction that the reader flagged: a factor-of-few uncertainty in sensitivity is secondary to a possible order-of-magnitude loss from period mismatch. The proposed check---comparing the Section 3.1 periods to the reference epochs and verifying the Table 1 extrapolation---will settle whether this is a typo or a methodological error. The verdict remains CONDITIONAL (i.e., unchanged) because the blind search and detection of known pulsars/RRAT validate the qualitative non-detection, and the quantitative limits can be repaired if the ephemeris is confirmed. I disagree with the reader's choice of weakest assumption only in that the period inconsistency should be resolved first.","tokens_in":11013,"tokens_out":12486,"duration_ms":111685,"concrete_test":"Compare the Section 3.1 periods with the reference-epoch periods in the cited X-ray timing papers (Camero et al. 2014; Kargaltsev et al. 2012; Dib & Kaspi 2014; Mereghetti et al. 2006). If they match, the text mistakenly quotes reference periods; then verify that Table 1 equals the linear extrapolation of P, Pdot to the FAST MJD using the X-ray ephemerides. If Table 1 is the correctly extrapolated period, the prepfold search presumably used Table 1, resolving the concern as a typographical error. If Table 1 does not match the extrapolation, re-run prepfold on the SGR 1900+14 dataset at both P=5.1579 s and P=5.19987 s; only the period that recovers an injected pulse with the expected S/N can support the quoted limit.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The periodic upper limits (S1250,red <= 16.9 uJy) depend entirely on folding at the correct spin period. Section 3.1 states the extrapolated periods at the start of the observations were 5.759819 s (SGR 0501+4516), 2.479967 s (Swift J1834.9-0846), 11.77364 s (1E 1841-045), and 5.1579 s (SGR 1900+14), but Table 1 lists P = 5.7620695(1), 2.4823018(1), 11.788978(1), and 5.19987(7) s, respectively. These differences (0.002-0.042 s) are far larger than the quoted uncertainties and correspond roughly to the periods at the earlier X-ray epochs, not the FAST epochs. If prepfold used the Section 3.1 values, the accumulated phase drift over 2100 s would be ~1-17 s, far exceeding the assumed 10% duty cycle (e.g., for SGR 1900+14, 404 periods x 0.042 s = 17 s), so any pulsed signal would be smeared below detectability and the derived upper limits would be meaningless. If Table 1 was used, the text is erroneous but the result stands. As written, the paper does not establish which period was used, so the headline upper limits are not reproducible. The duty-cycle/red-noise question raised by the reader is secondary; this inconsistency is more fundamental.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports FAST 1250 MHz observations of four magnetars (SGR 0501+4516, Swift 1834.9-0846, 1E 1841-045, SGR 1900+14) and the magnetar-like pulsar PSR J1846-0258, including PSR J1846-0258 about one month after its 2020 X-ray outburst. Using PRESTO, the authors searched for periodic pulsations and dispersed single pulses; no radio emission was detected from any target. They derive periodic flux upper limits from the radiometer equation with an assumed 10% duty cycle, then apply a red-noise correction based on the ratio of RMS noise in profiles folded at the source period and at 10 ms. The final quoted limits are S1250,red ≤ 16.9, 8.2, 13.9, 12.2, and 8.2 μJy for the five sources, plus single-pulse flux limits for 0.05-48 ms bursts. The authors also detected the known pulsar PSR J1907+0918 in the SGR 1900+14 pointing and RRAT J1846-0257 in the PSR J1846-0258 pointing, validating the search pipeline. The discussion interprets the non-detections as evidence that these sources are radio-quiet or unfavorably beamed at the observed epochs.","tokens_in":11329,"tokens_out":4249,"duration_ms":43552,"significance":"If the quantitative limits are correct, this work provides some of the deepest 1.25 GHz flux upper limits for these magnetars and particularly constrains PSR J1846-0258 near an active epoch following its 2020 outburst. The detection of known pulsars in the same pointings is a genuine strength, showing that the search pipeline would have found radio pulsations or single pulses if they were present above the quoted thresholds. The work also usefully documents a red-noise correction procedure for long-period sources. However, the quantitative claims rest on an unresolved inconsistency in the spin periods used for folding, so the significance of the quoted limits cannot be assessed until that is fixed.","major_comments":[{"comment":"There is a direct contradiction between the spin periods used for the periodic search and those listed in Table 1. Section 3.1 states that the extrapolated periods at the start of the observations were 5.759819 s (SGR 0501+4516), 2.479967 s (Swift J1834.9-0846), 11.77364 s (1E 1841-045), and 5.1579 s (SGR 1900+14), whereas Table 1 lists P = 5.7620695(1), 2.4823018(1), 11.788978(1), and 5.19987(7) s, respectively. These differences (0.002-0.042 s) are far larger than the quoted uncertainties. If prepfold was run with the Section 3.1 periods, the accumulated phase drift over the 2100 s observation would be about 0.8 s for SGR 0501+4516 and about 17 s for SGR 1900+14, far exceeding the assumed 10% duty cycle, so any periodic signal would be smeared below detectability and the quoted upper limits would be invalid. If Table 1 was used, the text is erroneous but the result stands. As written, the paper does not establish which period was actually used, so the headline upper limits are not reproducible. Please clarify and, if necessary, rerun the periodic search and upper-limit calculation with the correct epoch-dependent ephemerides.","section":"§3.1 and Table 1"},{"comment":"The red-noise correction is load-bearing for the quoted flux limits, but its validity is not demonstrated quantitatively. The method assumes that a profile folded at 10 ms contains only white noise and that the RMS ratio σp0/σ10ms fully captures the sensitivity loss from red noise. The paper reports the resulting limits but not the measured values of σp0/σ10ms for each source, nor any test of the white-noise assumption for the 10 ms fold (e.g., a χ² statistic or a comparison with an independent noise estimate). Without these numbers, the reader cannot assess how much the limits depend on this correction. Please report the measured ratios and quantify the systematic uncertainty they introduce, for example by comparing the red-noise correction derived from different reference periods or by using a noise model that accounts for the actual spectral index of the red noise.","section":"§3.3"}],"minor_comments":[{"comment":"The text says the single-pulse limits are 'between 2.9 and 135.9 μJy', while Table 1 lists maximum values of 89.0-121.4 mJy for S1250,single; the units and the maximum value are inconsistent between the text and the table.","section":"§3.3, Table 1"},{"comment":"The sentence 'within the same DM range and steps as previously described' is ambiguous because the DM range and steps have not yet been described in Section 3; clarify by referring explicitly to Section 2 or to the DDplan.py discussion.","section":"§3.1"},{"comment":"The quoted S1250,red values carry parenthetical uncertainties (e.g., 16.9(7) μJy), but the text does not explain how these uncertainties are derived from the radiometer equation and the red-noise ratio.","section":"Table 1"},{"comment":"The discussion treats the 2020 PSR J1846-0258 outburst as 'magnetar-like' but does not cite the high-energy burst trigger date precisely; consider giving the MJD or exact date to support 'one month after' in the abstract.","section":"§4"}],"recommendation":"major_revision","confidential_remarks":"The core qualitative result—no radio emission detected from any target—is probably robust because it is supported by blind searches and by the detection of known sources in the same pointings. However, the period inconsistency in §3.1 versus Table 1 is a load-bearing issue for the quantitative upper limits, and the red-noise correction needs better support. This is fixable within the manuscript's scope, so I recommend major revision rather than rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: the non-detections are believable, and the new flux limits are useful; but the paper has an internal period inconsistency that has to be resolved before anyone can safely quote those limits.\n\nWhat's actually new: the 1250 MHz upper limits for four magnetars and the high-B pulsar J1846-0258, including the first deep radio limit on J1846-0258 taken about a month after its 2020 X-ray outburst. The analysis uses stock PRESTO routines, but the sensitivity is genuinely better than previous searches for these objects, and the fact that the pipeline recovered PSR J1907+0918 in the SGR 1900+14 pointing and RRAT J1846-0257 in the J1846-0258 pointing is good internal validation.\n\nThe main problem is the spin-period discrepancy. Section 3.1 gives the extrapolated periods used for folding as 5.759819, 2.479967, 11.77364, and 5.1579 s for the four magnetars, while Table 1 lists 5.7620695(1), 2.4823018(1), 11.788978(1), and 5.19987(7) s. These are not measurement errors; they differ by up to 0.04 s. If the Section 3.1 values actually went into prepfold, the accumulated phase drift over the 2100-s observations would be several seconds for SGR 1900+14, which would smear any periodic signal beyond detection and invalidate the quoted limits. The text does not say explicitly which set of numbers was used. I suspect Table 1 is correct and the Section 3.1 sentence is a leftover from an earlier epoch, but the paper as written is not reproducible.\n\nThere is also an obvious unit typo: the text says the single-pulse limits are 2.9-135.9 uJy, while Table 1 correctly gives them in mJy.\n\nThe red-noise correction in Section 3.3 is a little ad hoc: folding at 10 ms as a white-noise reference is plausible, but the ratio sigma_p0/sigma_10ms is used without propagating any uncertainty, and the quoted parentheses on the limits reflect only the G and Tsky uncertainties, not the assumed 10% duty cycle. That is a minor caveat, not a fatal one.\n\nThe blind search with accelsearch does offer some safety: if a strong periodic signal were present, it likely would have been found regardless of the folding period. But the quantitative upper limits depend on having folded at the right period.\n\nRecommendation: deserve a serious referee. The measurements are worth having once the period question is clarified and the units fixed. A paper like this needs a moderate revision, not a desk reject.","headline":"Credible non-detections and useful flux limits, but a spin-period inconsistency between the text and Table 1 must be fixed before the limits can be quoted.","tokens_in":11901,"tokens_out":4773,"would_cite":true,"duration_ms":41848,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"No radio pulsations or bursts detected from four magnetars and PSR J1846-0258 with FAST at 1250 MHz, yielding flux limits down to 8.2 microjansky.","keywords":["magnetars","radio pulsations","single pulses","upper limits","FAST","PSR J1846-0258","red noise","radio-quiet neutron stars"],"falsifier":"Detect a periodic or single-pulse signal from any of the five targets at 1250 MHz with flux above the quoted limits in a comparable-length observation; that would show the non-detection was epoch-specific or the sensitivity estimate was too pessimistic.","tokens_in":10828,"feed_emoji":"📡","tokens_out":4451,"duration_ms":42029,"temperature":0.7,"pith_summary":"This paper reports a 2100-second radio search of four magnetars (SGR 0501+4516, Swift 1834.9-0846, 1E 1841-045, SGR 1900+14) and the magnetar-like pulsar PSR J1846-0258 with the Five-hundred-meter Aperture Spherical radio Telescope at 1250 MHz. No periodic pulsations and no single pulses were detected from any target, despite observing PSR J1846-0258 one month after its 2020 X-ray outburst while its X-ray pulse flux was still elevated. After correcting for red noise, the authors place upper limits on the pulsed flux density from 8.2 to 16.9 microjansky, among the deepest yet at this frequency for some of these sources. If these limits hold, the sources are either genuinely radio-quiet or their radio beams are not pointed at Earth during the observations.","feed_headline":"No radio pulses from five magnetars in deepest 1.25 GHz look","feed_subtitle":"Upper limits as low as 8.2 microjansky tighten the case that these neutron stars are radio-quiet or misaligned.","key_machinery":"The analysis rests on the 2100 s of 500 MHz bandwidth FAST data and two search pipelines from the PRESTO suite: prepfold folding at spin periods extrapolated from X-ray timing, and accelsearch for blind periodic searches, plus single_pulse_search.py for dispersed bursts. Sensitivity is set by the radiometer equation, and the key correction for long-period pulsars is a red-noise estimate: each observation is folded both at the source period and at a 10 ms period, the RMS of the two profiles is compared, and the ratio multiplies the white-noise flux limit to give the quoted upper limits.","core_discovery":"The central claim is that none of the five targets emitted detectable periodic or single-pulse radio emission during the FAST observations, and that the resulting upper limits are stringent enough to constrain their radio behavior. For the four magnetars and PSR J1846-0258, the red-noise-corrected 1250 MHz flux-density limits are 16.9, 8.2, 13.9, 12.2, and 8.2 microjansky respectively, with single-pulse limits in the 2.9-135.9 mJy range depending on pulse width. The observation of PSR J1846-0258 is notable because this high-B pulsar had just gone through a magnetar-like X-ray outburst, yet showed no radio emission, suggesting that either the radio emission mechanism was not activated despite the outburst, or the emission is beamed away from Earth or highly sporadic.","pith_inferences":["Stacking many short FAST observations could push sensitivity further and test whether the non-detections are persistent or arise from sporadic emission.","A simultaneous X-ray and radio campaign during a future outburst of PSR J1846-0258 would test whether radio emission tracks X-ray flux, as seen in some other magnetars.","The red-noise correction procedure could be validated by injecting synthetic pulsed signals into the data and recovering them, which would quantify the bias in the quoted limits."],"forward_implications":["If the sources are radio-quiet, searches at other frequencies and epochs should remain empty, strengthening the division between radio-loud and radio-quiet magnetars.","For PSR J1846-0258, the non-detection after an X-ray outburst narrows the conditions under which magnetar-like bursts switch on radio emission; it may be that only some outbursts or some geometries do.","The flux limits are several times below typical 1.4 GHz fluxes of known long-period pulsars, so any future detection from these targets would imply either transient activation or a narrow beam.","The single-pulse limits constrain FRB-like bursts from these magnetars during the observing windows, complementary to fast radio burst searches."],"supporting_citations":[{"why":"Supplies the radiometer equation used to convert noise level into flux-density limits.","marker":"Dewey et al. 1985"},{"why":"Motivates the red-noise correction for long-period pulsars and the folding approach.","marker":"Lazarus et al. 2015"},{"why":"Provides the PRESTO software used for periodic and single-pulse searches.","marker":"Ransom et al. 2002"},{"why":"Supplies receiver gain and noise temperature as functions of zenith angle for FAST.","marker":"Jiang et al. 2020"},{"why":"Gives the spin ephemeris for PSR J1846-0258 at the observation epoch.","marker":"Hu et al. 2023"},{"why":"Provides the spin parameters used to extrapolate the period of SGR 0501+4516.","marker":"Camero et al. 2014"},{"why":"Earlier deep Parkes limits for some of these magnetars that this work improves upon.","marker":"Crawford et al. 2007"},{"why":"The most recent FAST non-detection study of other magnetars, setting the context for the sensitivity achieved.","marker":"Lu et al. 2024"}],"fun_headline_variants":["Five magnetars silent in deepest FAST radio search","Post-outburst pulsar still quiet: five magnetars no-show","No pulses, no bursts: FAST tightens radio limits on magnetars","Magnetars remain radio-quiet under FAST's depth","Deep 1.25 GHz search finds no radio emission from five magnetars"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The quoted limits assume that the red-noise correction, derived by comparing a profile folded at the source period with one folded at 10 ms, correctly measures the sensitivity loss; if the 10 ms fold is not pure white noise, the limits could be off by a large factor.","fun_headline_variants_meta":{"raw":{"variants":["Five magnetars silent in deepest FAST radio search","Post-outburst pulsar still quiet: five magnetars no-show","No pulses, no bursts: FAST tightens radio limits on magnetars","Magnetars remain radio-quiet under FAST's depth","Deep 1.25 GHz search finds no radio emission from five magnetars"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000296,"raw_usage":{"total_tokens":1735,"prompt_tokens":976,"completion_tokens":759,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":592,"completion_tokens_details":{"reasoning_tokens":671}},"tokens_in":592,"tokens_out":759,"duration_ms":8022,"temperature":1.0,"reasoning_tokens":671,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-10T23:36:10.965197+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Detect a periodic or single-pulse signal from any of the five targets at 1250 MHz with flux above the quoted limits in a comparable-length observation; that would show the non-detection was epoch-specific or the sensitivity estimate was too pessimistic.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Earlier deep Parkes limits for some of these magnetars that this work improves upon."}],"review_version":1}