{"id":"67fc9dcb-864e-4c3c-8b89-9bd085a635a4","arxiv_id":"2412.03062","paper_version":2,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"The GPPS survey reports 116 binary pulsars, phase-connected timing solutions for 29, and total masses for two double neutron star systems from periastron advance.","lead":"The FAST radio telescope survey has found 116 new binary pulsars in the Galactic plane, greatly expanding the known sample of pulsars with white dwarf, neutron star, and planetary companions. Two double neutron star systems have measured orbital advance rates that give their total masses under general relativity.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The J1844-0128 periastron-advance mass is the load-bearing weak point: at 3.3 sigma and 154-microsecond residuals, the derived 1.7(8) M_sun total mass is consistent with a non-DNS companion, so the 'second DNS mass' claim is not yet secure.","rationale":"The phase-connected timing solutions have internally consistent residuals (1-175 us) and reduced chi-square values near unity, and the 78 provisional Keplerian systems are explicitly labeled as lacking full timing solutions, so the survey discovery claim is not the main problem. The load-bearing step is the interpretation of the marginal J1844-0128 periastron advance as a secure DNS mass. This is the same concern the reader identified, and I agree with its substance. My additional point is that the resulting mass value is itself inconsistent with the DNS interpretation at face value: with the measured mass function, M_tot = 1.7 M_sun implies companion masses of 0.63-0.73 M_sun, below the neutron-star range. Thus either the dot-omega measurement is biased by fitting covariance or unmodeled effects, or the companion is more likely a massive white dwarf. The paper should therefore present J1844-0128 as a DNS candidate rather than a second secure DNS mass measurement. This does not undermine the 116-pulsar discovery claim or the J0528+3529 mass measurement, so the existing CONDITIONAL verdict is appropriate and no verdict change is needed.","tokens_in":53404,"tokens_out":12615,"duration_ms":127151,"concrete_test":"Refit PSR J1844-0128 using the same TOAs in an independent timing package (e.g., PINT) with the DDGR model, which fits the total mass directly under GR, and compare with the DD-fit result. If the independent best-fit total mass differs from 1.7(8) M_sun by more than 1 sigma, or if the posterior probability that both component masses are greater than or equal to 1.1 M_sun is below 5%, then the periastron-advance mass is not robust and the paper should claim only one secure DNS mass (J0528+3529).","verdict_should_be":"UNCHANGED","load_bearing_attack":"The catalog itself (116 binaries, 29 phase-connected timing solutions) is credible, but the specific claim of 'two new DNS mass measurements' rests on Eq. (2) applied to PSR J1844-0128 (Section 3.5, Table A1). Its dot-omega = 0.0059(18) deg/yr is a 3.3-sigma effect, measured on 59 TOAs with a 154-microsecond residual, and the paper gives no covariance matrix or independent check. Moreover, the value is in tension with the 'NS' classification: with f = 0.0881 M_sun (Table 3), a total mass of 1.7 M_sun forces the companion mass to 0.63-0.73 M_sun for i = 90-60 degrees and a pulsar mass of about 0.97-1.07 M_sun, which is not a plausible double neutron star. A covariance bias in the DD fit, or an unmodeled contribution, could easily shift dot-omega to a value corresponding to M_tot > 2.2 M_sun, but that has not been demonstrated. Until the measurement is checked with an independent timing model, the J1844-0128 result should be presented as a candidate mass, not a secure DNS mass; the paper's central claim otherwise stands.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper presents 116 binary pulsars discovered in the FAST Galactic Plane Pulsar Snapshot survey. For all 116 systems, preliminary Keplerian orbital parameters are derived from observed barycentric period variations; for 29 of them, phase-connected timing solutions are obtained, with residuals of 1-175 microseconds and reduced chi-squared near unity. Two systems, PSR J0528+3529 and PSR J1844-0128, are identified as double neutron star candidates, and the general-relativistic periastron advance dot-omega is used to derive total masses of 2.90(12) and 1.7(8) M_sun, respectively. The paper also reports companion classifications for the sample, eclipse detections for eight systems, polarization profiles for 29 pulsars, and an optical counterpart for the companion of PSR J1908+1036.","tokens_in":53648,"tokens_out":6623,"duration_ms":60570,"significance":"If the two DNS mass measurements were secure, this would be a valuable addition to the DNS mass sample and a strong demonstration of the survey's follow-up capability. The 29 phase-connected timing solutions are genuinely useful for future timing and evolution studies, and the full sample of 116 binaries substantially enlarges the Galactic binary pulsar census, especially the He-WD and CO/ONe-WD populations. The polarization profiles and eclipse detections are also useful. However, the significance of the paper as stated in the abstract rests on the two DNS mass measurements; one of them (J1844-0128) is marginal and internally inconsistent, so the paper's headline claim is stronger than the data support.","major_comments":[{"comment":"The presentation of PSR J1844-0128 as a double neutron star system with a measured total mass of 1.7(8) M_sun is not supported by the quoted numbers. The mass function f = 0.0881 M_sun (Table 3) together with M_tot = 1.7 M_sun forces the companion mass to about 0.63-0.73 M_sun for pulsar masses of 0.97-1.07 M_sun and inclinations of 90-60 degrees, which is far below the observed neutron star mass range and actually outside the NS criterion (mc,med > 0.76 M_sun) used in Table 1. The 3.3-sigma dot-omega measurement is therefore insufficient to claim a DNS mass. Please present this as a candidate DNS with a candidate total mass, and revisit the 'NS' companion classification for this system in Table 3.","section":"Section 3.5, Table A1, and Table 3"},{"comment":"The 'Keplerian parameters' listed for the 78 pulsars without timing solutions are obtained from fits that fix the eccentricity to zero (as shown by the 'e = 0.0' labels in every panel of Figure A3), but this assumption is not stated in Table 3, where the e column is simply left blank, and no uncertainties are quoted for Pb, x, or T0. Because the abstract claims Keplerian parameters for all 116 systems, the circular-orbit assumption should be explicitly marked (e.g., 'e = 0 (fixed)') and the preliminary nature of these parameters should be emphasized; otherwise the table and abstract overstate what is measured.","section":"Section 3, Table 3, and Figure A3"},{"comment":"The dot-omega measurement for PSR J1844-0128 rests on 59 TOAs with a 154-microsecond residual and is only a 3.3-sigma detection. The paper does not provide any check for covariance between dot-omega and the other DD model parameters (e, omega, Pb, x) or for systematic timing errors. Since this is the only basis for the claimed total mass, please add a robustness analysis (e.g., splitting the data, fitting subsets, or a residual inspection without dot-omega) or discuss the systematic uncertainty explicitly.","section":"Section 3.5 and Table A1"}],"minor_comments":[{"comment":"The phrase 'the the Five-hundred-meter' contains a duplicated article.","section":"Abstract and Section 1"},{"comment":"'Kepelerian parameters' should be 'Keplerian parameters'.","section":"Section 4"},{"comment":"'soliday single pulsars' should be 'solitary single pulsars'.","section":"Figure 11 caption"},{"comment":"'constraints of EOS and and the understanding' contains a doubled 'and'.","section":"Section 1"},{"comment":"For the 78 preliminary systems, add a footnote stating that eccentricity and longitude of periastron are not fitted (fixed to e = 0) and that Pb, x, and T0 come from the fits shown in Figure A3.","section":"Table 3"},{"comment":"The longitude of periastron is printed as '= 0.0 o' and would be clearer as 'omega = 0.0 deg'.","section":"Figure A3"}],"recommendation":"major_revision","confidential_remarks":"The catalog and the 29 phase-connected timing solutions are credible and will be useful to the community. My main concern is the over-interpretation of the J1844-0128 dot-omega measurement; I would recommend that the authors reframe this as a candidate DNS mass and provide a robustness check. The paper is otherwise within the scope of the journal and, after the requested revisions, would be acceptable."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Bottom line: this is a solid survey paper that deserves peer review. The real new results are the catalog itself and the secure DNS mass for J0528+3529. The second DNS mass, J1844-0128, should not be presented as secure.\n\nThe catalog of 116 binary pulsars is a clear contribution. The 29 phase-connected timing solutions are internally consistent (residuals 1–175 us, reduced chi^2 near 1), and the parameters for those systems look reliable. The J0528+3529 dot-omega of 0.0072(3) deg/yr is a clean detection from 23 TOAs with 6 us residual, giving total mass 2.90(12) M_sun; that is a valuable addition to the DNS sample. The polarization profiles and companion-type statistics also add value, and the sample visibly fills the orbital-period gaps.\n\nSoft spots, in rough order of importance:\n\n1. J1844-0128. dot-omega = 0.0059(18) deg/yr is a 3.3-sigma detection from 59 TOAs with 154 us residual. The implied total mass of 1.7(8) M_sun leaves the companion at roughly 0.7 M_sun for a pulsar near 1 M_sun, which is equally consistent with a massive WD as with an NS. The abstract and Section 3.5 call it a double neutron star; the paper should call it a candidate DNS or a candidate mass, and ideally check the fit with an independent timing model.\n\n2. Counting error. Section 4 lists 59 He-WD + 24 CO/ONe + 11 UL + 5 MS + 3 NS + 1 He star + 12 unknown = 115, while the abstract and Section 3.1/3.2 imply 116. The discrepancy is internal and should be fixed.\n\n3. The 78 preliminary Keplerian fits have no quoted uncertainties and e fixed to zero. They are explicitly labeled preliminary, which is honest, but adding errors would help.\n\n4. The optical counterpart for J1908+1036 is claimed on the basis of a visual inspection of Pan-STARRS images. That is weak evidence; at least a separation measurement or color-magnitude check should be added.\n\nThe paper is for pulsar astronomers and anyone working on binary evolution or NS masses. It deserves a serious referee, with minor-to-moderate revision. The catalog and J0528 mass should be published; the J1844 claim needs rephrasing or additional timing data. I would cite this paper for the catalog and the J0528 mass.","headline":"Solid catalog paper with one secure DNS mass and one candidate that is oversold.","tokens_in":54349,"tokens_out":5671,"would_cite":true,"duration_ms":48792,"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":"The FAST GPPS survey reports 116 new binary pulsars: Keplerian orbits for all, timing solutions for 29, and relativistic masses for two double neutron stars.","keywords":["binary pulsars","millisecond pulsars","double neutron stars","post-Keplerian parameters","periastron advance","pulsar timing","FAST GPPS survey","white dwarf companions"],"falsifier":"Continue timing PSR J1844-0128 over a longer baseline with proper motion and dispersion-measure variations included in the fit: if $\\dot{\\omega}$ is not recovered above five $\\sigma$ or shifts by more than its current uncertainty, the claimed $1.7(8)\\,M_\\odot$ total mass fails. Alternatively, a Shapiro-delay measurement in PSR J0528+3529 that gives individual masses inconsistent with the total $2.90(12)\\,M_\\odot$ would falsify the general-relativistic interpretation.","tokens_in":53128,"feed_emoji":"🔭","tokens_out":9629,"duration_ms":79582,"temperature":0.7,"pith_summary":"This paper reports that the FAST Galactic Plane Pulsar Snapshot survey has turned up 116 pulsars in binary systems, a substantial enlargement of the known Galactic-field binary pulsar sample. For all 116 it provides Keplerian orbital parameters derived from FAST timing, and for 29 of them it presents phase-connected timing solutions spanning one to five years. The companions are classified as helium white dwarfs, CO/ONe white dwarfs, neutron stars, main-sequence stars, or ultra-light objects, and eight systems show eclipses. The quantitative centerpiece is the measurement of the post-Keplerian periastron advance in the double neutron star systems PSR J0528+3529 and PSR J1844-0128, which, under general relativity, gives total masses of 2.90(12) and 1.7(8) solar masses.","feed_headline":"FAST survey adds 116 binary pulsars, two new neutron-star pair masses","feed_subtitle":"Keplerian orbits for all 116, phase-connected timing for 29, and GR masses for two double neutron stars.","key_machinery":"The argument is carried by two standard binary-pulsar relations. The Keplerian mass function, $f = (m_c \\sin i)^3 / (m_p + m_c)^2 = 4\\pi^2 x^3 / (T_\\odot P_b^2)$, converts the fitted orbital period $P_b$ and projected semi-major axis $x$ into a companion-mass estimate, which is the basis for classifying companions when paired with spin period, orbital period, and eccentricity. The general-relativistic periastron-advance relation, $\\dot{\\omega} = 3 T_\\odot^{2/3} (P_b / 2\\pi)^{-5/3} (1-e^2)^{-1} (m_p + m_c)^{2/3}$, converts a measured $\\dot{\\omega}$ directly into the total binary mass, without needing the inclination angle. Timing fits use the ELL1 model for nearly circular orbits and the DD model for eccentric ones, with phase connection linking observations across gaps.","core_discovery":"The paper establishes that the FAST GPPS survey has discovered 116 pulsars in binary orbits and measures their Keplerian parameters, with orbital periods ranging from 0.037 days to 826 days, projected semi-major axes, and eccentricities. For 29 of these, including the two double neutron star systems, it obtains phase-connected timing solutions with residuals as low as 1.053 microseconds. It classifies companion types from the mass function and orbital properties, identifies eight eclipsing systems, and locates the optical counterpart of the companion of PSR J1908+1036. The central quantitative result is the measurement of the relativistic periastron advance, $\\dot{\\omega} = 0.0072(3)$ deg/yr for PSR J0528+3529 and $\\dot{\\omega} = 0.0059(18)$ deg/yr for PSR J1844-0128, from which the general-relativistic formula (Eq. 2) yields total masses of $2.90(12)\\,M_\\odot$ and $1.7(8)\\,M_\\odot$.","pith_inferences":["If the paper's claim for PSR J0528+3529 holds, a total mass near $2.9\\,M_\\odot$ would put the system on the high side for double neutron stars, so measuring Shapiro delay to split the individual masses would be a direct test of whether one component is an unusually massive neutron star.","The marginal periastron-advance detection for PSR J1844-0128 suggests that many of the 78 pulsars without timing solutions may hide additional relativistic binaries, so extending the timing campaign on those sources is a cheap way to grow the double neutron star census.","Because companion types are inferred from median masses assuming a $1.35\\,M_\\odot$ pulsar and an inclination of 60 degrees, the reported fractions of He-WD and CO/ONe-WD companions will likely shift once individual masses or inclinations are measured.","A selection-effect simulation of the snapshot survey would be needed to know whether the high WD-companion fraction reflects the true Galactic-plane population or the survey's sensitivity to recycled pulsars."],"forward_implications":["The Galactic-field binary pulsar census grows by 116 systems, making the combined sample the largest available for studying binary evolution and companion-type statistics.","The two double neutron star total masses, $2.90(12)\\,M_\\odot$ and $1.7(8)\\,M_\\odot$, add new anchors for neutron-star mass measurements and for tests of gravitational theories in the strong-field regime.","The eight newly identified eclipsing binaries, including black widows and redbacks, provide targets for studying the outflowing material and geometry of the companion winds.","The confirmed gaps in the He-WD orbital-period distribution, with enhanced peaks, support the Case A versus Case B Roche-lobe overflow formation channels for these systems.","The 29 phase-connected timing solutions give precise ephemerides and polarization profiles that can be used for continued monitoring of post-Keplerian effects such as Shapiro delay."],"supporting_citations":[{"why":"Defines the GPPS snapshot survey design and observing mode that produced the pulsar discoveries.","marker":"Han et al. 2021"},{"why":"Supplies the GPPS catalogue of 751 pulsars from which the 116 binary systems are drawn.","marker":"Han et al. 2025"},{"why":"Reports the first GPPS double neutron star, PSR J1901+0658, establishing the DNS identification and timing approach this paper extends.","marker":"Su et al. 2024"},{"why":"Provides the relativistic periastron-advance formalism underlying Eq. (2).","marker":"Blandford & Teukolsky 1976"},{"why":"Provides the DD binary timing model and the leading-order periastron-advance parameterization used for the eccentric DNS fits.","marker":"Damour & Deruelle 1985"},{"why":"Supplies the companion classification criteria and evolutionary channels adopted in Table 1 and Section 3.","marker":"Tauris et al. 2012"},{"why":"Provides the phase-connection method used to obtain the 29 phase-connected timing solutions.","marker":"Freire & Ridolfi 2018"},{"why":"Gives the ATNF pulsar catalogue used as the baseline for the known binary population and comparison fractions.","marker":"Manchester et al. 2005"}],"fun_headline_variants":["116 new binary pulsars from FAST, two yield neutron-star masses","FAST discovers 116 binary pulsars, measures two double-neutron-star masses","Fast survey nets 116 pulsars in binaries, times 29, weighs two neutron-star pairs","116 binary pulsars from FAST, including two new neutron-star mass measurements","FAST finds 116 binary pulsars, identifies 8 eclipsing systems, weighs two neutron stars"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The total-mass values for the two double neutron star systems assume that the entire measured periastron advance is caused by general relativity; for PSR J1844-0128 this is fragile because the advance is only a marginal 3.3-$\\sigma$ detection on a 154-microsecond timing residual, so an unmodeled contribution or fitting covariance could change the derived $1.7(8)\\,M_\\odot$ total mass.","fun_headline_variants_meta":{"raw":{"variants":["116 new binary pulsars from FAST, two yield neutron-star masses","FAST discovers 116 binary pulsars, measures two double-neutron-star masses","Fast survey nets 116 pulsars in binaries, times 29, weighs two neutron-star pairs","116 binary pulsars from FAST, including two new neutron-star mass measurements","FAST finds 116 binary pulsars, identifies 8 eclipsing systems, weighs two neutron stars"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000981,"raw_usage":{"total_tokens":4170,"prompt_tokens":959,"completion_tokens":3211,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":575,"completion_tokens_details":{"reasoning_tokens":3101}},"tokens_in":575,"tokens_out":3211,"duration_ms":22148,"temperature":1.0,"reasoning_tokens":3101,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T22:48:54.764759+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Continue timing PSR J1844-0128 over a longer baseline with proper motion and dispersion-measure variations included in the fit: if $\\dot{\\omega}$ is not recovered above five $\\sigma$ or shifts by more than its current uncertainty, the claimed $1.7(8)\\,M_\\odot$ total mass fails. Alternatively, a Shapiro-delay measurement in PSR J0528+3529 that gives individual masses inconsistent with the total $2.90(12)\\,M_\\odot$ would falsify the general-relativistic interpretation.","supporting_citations":[],"review_version":1}