{"id":"8d5dd284-c679-46c0-9dc7-4cf4a2e09e53","arxiv_id":"2506.08751","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":8.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"The paper reports the first high-signal detection of interstellar SII K-beta absorption and a direct measurement of sulfur depletion (40% ± 15%) from combined gas and dust absorption in the GX 340+0 sightline.","lead":"Using XRISM and Chandra spectra of two distant X-ray binaries, the authors detected an interstellar sulfur absorption line and measured how much sulfur is locked in dust. This is the first direct census of gas and solid sulfur in one sightline, yielding a 40% depletion estimate for the Milky Way's diffuse interstellar medium.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Solid-S detection and 40% depletion rely on attributing residuals to Fe-S dust after a +8 eV ad hoc SII template shift; the single −1 eV relative-line test cannot exclude atomic-model errors, so gas/dust decomposition is not yet uniquely constrained.","rationale":"The reader's conditional verdict already targets the dust attribution, and my stress-test agrees that this is the least secure link in the paper's central claims. The interstellar nature of the absorption is well supported: the same Kβ feature is seen in two sources, two instruments, and multiple flux states, and the source-intrinsic photoionized alternatives (S XV, Si XIV) require implausible velocity shifts and columns (§4.4). That part of the argument is strong. The fragility is specifically the decomposition into gas plus solid. The SII template fit alone is only made possible by an empirical +7.9 eV shift, and no laboratory measurement exists to validate the template's absolute energy scale or, more importantly, its relative line spacings. The paper's −1 eV test is a useful start but under-powers the concern: it tests one ad hoc adjustment of the higher-order lines, not the range of plausible errors in a theoretical cross-section whose Kβ predictions differ by 5–10 eV across methods (§2). The dust templates themselves are also laboratory XANES spectra with their own energy-scale uncertainties and were not collected for astrophysical comparison, as the authors note (§4.3). A laboratory SII cross-section, or a fit that allows independent group shifts, would directly test whether the 2.485 keV residual is truly solid S. Until then, the 40±15% depletion and solid-S detection should remain conditional, exactly as the reader concluded. I do not see grounds to reject the paper; the central SII Kβ detection and centroid measurement are credible.","tokens_in":19260,"tokens_out":9007,"duration_ms":110952,"concrete_test":"Re-fit the two XRISM GX 340+0 exposures with the forthcoming laboratory SII K-shell cross-section, allowing no global free energy shift but fitting independent energy offsets for the Kβ and Kγ/higher-order line groups, and include the Fe-S dust templates. If the lab cross-section places Kβ at 2470.8 eV and the ~2.485 keV residual persists with a solid-S column near 5×10^17 cm^-2, the dust detection and depletion measurement stand. If the residual is absorbed by the lab atomic model, or by relative line offsets within the lab calibration uncertainty, the solid-S attribution is not unique and the 40±15% depletion should be treated as an upper limit pending better atomic data.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The depletion measurement in §4.3–§5 depends on the residual absorption at ~2.485 keV being solid S-bearing dust, but this residual sits immediately beside the SII Kγ and higher-order Rydberg complex of the Gatuzz et al. (2024) template. The atomic template is applied with a uniform +7–8 eV shift (§4.2, Table 2), and the paper acknowledges the template 'warrants improvements' (§5). If the model error is not a uniform absolute energy shift but an energy-dependent error in the relative positions or strengths of the Kβ, Kγ, and higher-order lines, the residual could be unmodeled atomic SII rather than dust. The test in §5 shifts the high-energy lines by only −1 eV; it improves the gas-only fit by ΔC=20 but does not scan the plausible range of relative-line errors, and for the gas+dust fit it leaves all parameters within 1σ without excluding a continuum of alternatives. The Fe-S dust templates also overlap the Kβ feature, forcing a further ~0.5 eV shift of the SII template (§4.3), so the solid-S column and the 40±15% depletion are partially degenerate with the atomic model. Laboratory SII K-shell photoabsorption cross-sections are absent (§2), leaving no external calibration of the template's energy scale or line spacings.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper uses XRISM Resolve and archival Chandra HETG spectra to study interstellar sulfur K-shell photoabsorption toward two Galactic X-ray binaries, 4U 1630-472 and GX 340+0. The central observational result is a persistent absorption feature at 2470.8±1.1 eV (statistical plus systematic), identified as the SII Kβ line because its position is stable across two sources, two instruments, and multiple flux/accretion states, and because plausible photoionized-absorber contaminants (SXV, SiXIV) would need large, unphysical velocity shifts or are excluded by existing wind models. The centroid is measured with a template-independent Voigt fit. The authors further show that the SII absorption template of Gatuzz et al. (2024) must be shifted by +7 to +8 eV to match the data, a shift comparable to the spread among theoretical predictions (Palmeri et al. 2008; Witthoeft et al. 2011; FAC). In the 300 ks XRISM spectrum of GX 340+0, residual absorption near 2.485 keV is fit with Fe-S dust absorption templates (troilite, pyrrhotite, pyrite), which are mutually indistinguishable but give consistent S-in-dust columns. Combining gas and solid S yields a direct S depletion measurement of 40±15% toward GX 340+0 and an upper limit of <25% on Fe bound in Fe-S compounds. The authors suggest these ~11 kpc far-disk sightlines may represent the average Milky Way S depletion.","tokens_in":19570,"tokens_out":27726,"duration_ms":295301,"significance":"If the SII Kβ identification is correct, the measured centroid is an important observational anchor for sulfur K-shell atomic physics: no laboratory SII K-shell cross-sections exist, and theory predictions for the Kβ position differ by 5-10 eV. The demonstrated +7 to +8 eV energy-scale shift in the Gatuzz et al. (2024) template resolves a prior inconsistency in which X-ray fits gave SII <4% of the S column although SII is the dominant diffuse-ISM ion in UV studies. The gas-plus-dust decomposition toward GX 340+0, if it holds, is the first direct census of gaseous and solid S along one sightline and the first X-ray measurement of S depletion. The paper is commendable for its treatment of systematics: gain-calibration checks (pixel-30 gain jump, bright-source effects), pileup mitigation, explicit contamination checks against SXV and SiXIV lines, a template-independent centroid measurement, an internal consistency test (template-only S column equals the sum of the gas and dust columns), and unusually transparent statements of the atomic-template limitations and the forthcoming laboratory data.","major_comments":[{"comment":"The solid-S detection and the 40±15% depletion are headline results, and they depend entirely on attributing the residual absorption near 2.485 keV to Fe-S dust rather than to errors in the SII atomic template. The evidence for this attribution is not yet sufficient. The paper's only test of a non-uniform template error is a single −1 eV shift of the lines above 2.478 keV (§5). This test is too narrow in two respects. First, the perturbation size (1 eV) is far smaller than the 5-10 eV scatter among the theoretical predictions shown in Figure 1, and the paper neither quantifies the plausible range of relative line-placement errors nor scans that range. Second, in the gas+dust fit the Fe-S dust templates have structure across the same 2.47-2.49 keV region as the Kβ/Kγ complex, so the reported ΔC=2 improvement (versus ΔC=20 in the gas-only fit) and the statement that parameters are within 1σ do not demonstrate that the dust column is insensitive to atomic-model error; the dust template can simply absorb the shifted atomic structure. The −1 eV test therefore does not exclude the hypothesis that the residual is misplaced or mis-strengthened atomic SII lines. I recommend repeating the analysis with (i) relative shifts of the higher-order SII lines scanned over roughly ±5 eV, (ii) independent energy-scale shifts of each dust template (whose laboratory calibration the paper itself flags as uncertain in §4.3), and (iii) an explicit test of whether the dust column goes to zero within the allowed error range. If it can, the solid-S detection should be presented as tentative or as an upper limit, and the depletion claim must be re-scaled accordingly.","section":"§4.3, §5, Tables 2–3, Fig. 1"},{"comment":"The quoted depletion, 40±15%, does not include the dominant sources of systematic uncertainty in the gas/dust decomposition. The ±15% appears to reflect the statistical errors on the individual column densities and the small spread among the three compounds (37-42%) in Table 3. It does not propagate (i) the unknown relative positions and strengths of the SII Rydberg lines, (ii) the absolute energy-scale calibration of the laboratory dust cross-sections (a calibration the paper acknowledges in §4.3 is subject to re-evaluation), or (iii) the assumed grain-size distribution (power law with slope −3.5, sizes 0.005-0.25 µm) and the Mie-theory treatment used to build the dust templates. A concrete illustration of the problem is the paper's own finding that adding the dust templates shifts the best-fit SII template by about 0.5 eV relative to the gas-only fit (Table 2 versus Table 3); that shift directly repartitions flux between the Kβ line and the dust features, and its effect on the depletion is not included in the quoted uncertainty. I request an explicit systematic error budget for the depletion, or a table giving the depletion at the endpoints of the relevant template-shift and dust-calibration ranges, so that the headline value reflects the model dependence of the decomposition.","section":"§4.3, Table 3, §5"}],"minor_comments":[{"comment":"In the two 4U 1630−472 XRISM rows, the K-edge position (2480.9 +3.1/−2.6 eV) and K-edge strength (0.184±0.008) are quoted to identical values in both flux states; if these were genuinely independent fits, identical values to the quoted precision are implausible, so please clarify whether the edge parameters were held tied between the states or report the separate fitted values.","section":"Table 1"},{"comment":"The suggestion that these two sightlines may represent the average S depletion of the Milky Way is a strong extrapolation from two lines of sight separated by only a few degrees on the sky (both near l≈336–339°, |b|≤0.3°, i.e., essentially one direction through the far disk); the paper should temper this claim or provide a sampling argument.","section":"§5 and Abstract"},{"comment":"The upper limit of <25% for Fe bound in Fe-S compounds depends on the assumed Fe/S abundance ratio: adopting Fe/S = 1.6 (the low end of the 1.6–2.5 range the paper cites) together with the troilite solid-S column yields a fraction near 25–26%, so the limit should be quoted as a function of the adopted reference abundance.","section":"§5"},{"comment":"The analysis cites several unpublished works for supporting numbers: Miller et al. (ApJL in review) for the 4U 1630−472 wind census, Eckart et al. (JATIS 2025, in prep) for the 1 eV gain systematic below 5.4 keV, and Ludlam et al. and Chakraborty et al. (in prep) for the GX 340+0 Z-track and wind analyses; please confirm these works are available, or state the key quantities independently in this paper.","section":"§3 and §4.4"},{"comment":"Figure 3 quotes ΔBIC while Table 3 and §5 quote ΔC (Cash statistic), making the reported improvements hard to compare; please state which statistic applies at each location.","section":"Fig. 3 and Table 3"},{"comment":"The phrase 'high-signal detection ... in the spectrum of X-ray binaries 4U 1630-472 and GX 340+0' is stronger than the per-dataset significances for 4U 1630−472 suggest: the XRISM low-flux state gives N_SII = 64(+77,−50)×10^16 cm^-2, consistent with zero at roughly 1.3σ, so the detection toward that source is carried mainly by the combined HEG data; stating per-dataset significances would let the reader judge the strength of the two-source claim.","section":"Abstract and Table 1"},{"comment":"Please correct typographical errors: the §4 heading reads 'Fitting Methods and and Results' (duplicated 'and'), §4.1 contains 'V oigt' with a spurious space, and §5 uses unspaced 'SIItemplate'.","section":"§4 heading, §4.1, §5"}],"recommendation":"major_revision","confidential_remarks":"The paper fits the journal's scope well as an early XRISM ISM result, and the first-detection claim for SII Kβ appears plausible given the prior upper limit from Gatuzz et al. (2024). The main editorial concern beyond the technical points is that the analysis depends on several unpublished companion papers for supporting quantities; the editor may wish to verify that these are genuine members of the collaboration's publication pipeline before the revision is judged. If the authors are unable to strengthen the gas/dust decomposition tests, the paper could still be publishable with the dust/depletion claims explicitly demoted to tentative status, while the centroid and template-shift results stand on their own."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The headline result holds up: this is the first high-signal detection of interstellar SII K-beta, and the measured centroid at 2470.8 ± 1.1 eV is convincing. The feature appears in two different XRBs, with XRISM and Chandra, across multiple flux states, so the interstellar attribution is solid. The authors also measure the line with a Voigt profile independent of the theoretical template, then show the Gatuzz et al. template needs a +7–8 eV shift. That shift is a real finding about atomic data, not a fitting artifact.\n\nWhat is genuinely new: the SII K-beta detection itself, the template energy-shift result, and the first attempt at a direct gas-plus-dust sulfur census. The paper does careful work on gain calibration and photoionized-absorber contamination, and the three Fe-S dust templates give consistent solid-S columns. That is a meaningful step.\n\nWhere I get cautious: the dust attribution and the 40 ± 15% depletion rest on residuals near 2.485 keV, which sit right next to the SII K-gamma complex. The authors test a −1 eV shift of the higher-order lines, which improves the gas-only fit by ΔC = 20, but they do not scan the plausible range of relative-line errors. So they cannot fully exclude atomic-model misplacement as the source of those residuals. They also admit the Fe-S templates overlap the K-beta feature and force another ~0.5 eV shift, so the solid-S column is partially degenerate with the atomic model. To their credit, they flag this limitation explicitly and note that laboratory S K-shell cross-sections are forthcoming. That makes the depletion a well-motivated interpretation rather than a locked-in measurement.\n\nMinor: the data are under embargo and no scripts are provided, so independent checks will have to wait. That is normal for XRISM at this stage, but it does limit immediate reproducibility.\n\nBottom line: this is a careful, honest paper. The SII K-beta detection and centroid are publishable results on their own; the depletion is a useful first estimate with caveats the authors mostly state themselves. It deserves a serious referee and will likely become the standard reference for X-ray studies of interstellar sulfur.","headline":"Solid new SII K-beta detection; the 40% depletion is a reasonable reading of the residuals but still leans on uncalibrated atomic shifts, and the paper says so.","tokens_in":697,"tokens_out":756,"would_cite":true,"duration_ms":31971,"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":"XRISM's high-resolution spectra of two distant X-ray binaries give the first unambiguous detection of interstellar SII K$\\beta$ absorption at 2470.8$\\pm$1.1 eV and yield a direct measurement of sulfur depletion: 40%$\\pm$15% of…","keywords":["interstellar sulfur","X-ray absorption spectroscopy","SII K-beta line","sulfur depletion","interstellar dust","Fe-S compounds","XRISM","X-ray binaries"],"falsifier":"Measure the SII K-shell photoabsorption cross-section in the laboratory, or compute it with a fully converged method that reproduces the observed K$\\beta$ position, then fit the XRISM spectrum of GX 340+0 with the corrected atomic template alone. If the residual near 2.485 keV disappears without any dust component, the solid-sulfur detection and the 40% depletion measurement are artifacts of the atomic template; if the residual persists, the dust identification stands. A second XRISM observation of another obscured X-ray binary at comparable signal-to-noise that fails to reproduce the same line position and residual pattern would also challenge the interstellar interpretation.","tokens_in":19068,"feed_emoji":"🔭","tokens_out":7333,"duration_ms":78592,"temperature":0.7,"pith_summary":"This paper reports the first unambiguous X-ray detection of interstellar atomic sulfur (SII) K$\\beta$ absorption, seen in the spectra of two distant X-ray binaries, 4U 1630-472 and GX 340+0. The line appears at the same energy, 2470.8$\\pm$1.1 eV, across two instruments, two targets, and different brightness states, which identifies it as interstellar rather than intrinsic to the sources. The authors also find that the best current atomic template for SII absorption must be shifted by +7 to 8 eV to match the data, exposing a gap in theoretical sulfur atomic physics. In the deepest spectrum, GX 340+0, absorption left over after removing the atomic SII component is matched by iron-sulfur dust templates (troilite, pyrrhotite, or pyrite), giving the first direct measurement of sulfur depletion in the interstellar medium: 40%$\\pm$15% of interstellar sulfur is locked in dust. Because both sources lie about 11 kpc away on opposite sides of the Galactic disk, the authors suggest this depletion value may represent the Milky Way average.","feed_headline":"40% of Milky Way sulfur is locked in dust","feed_subtitle":"First clear SII K-beta detection pins the line at 2470.8 eV and directly weighs sulfur gas plus dust.","key_machinery":"The carrier of the argument is K-shell photoabsorption spectroscopy of sulfur at roughly 2.45 to 2.5 keV, where inner-shell electrons of SII produce a strong K$\\beta$ resonance plus Rydberg series and a K-shell edge. Because the absorption is imprinted on the X-ray continuum of background binaries, the line energy, equivalent width, and continuum edge strength measure the gas-phase sulfur column; residual structure after subtracting the atomic cross-section is attributed to solid sulfur-bearing dust, with Mie-theory absorption cross-sections for troilite, pyrrhotite, and pyrite converted from laboratory optical constants. The paper's central operation is fitting the observed spectra with a shifted SII template plus a dust template, then converting the fitted columns into a depletion fraction relative to the total sulfur column inferred from continuum absorption.","core_discovery":"The central discovery is that XRISM's resolving power makes interstellar sulfur visible in both its gaseous and solid forms along one sightline. The SII K$\\beta$ resonance is detected at high significance and pinned at 2470.8$\\pm$1.1 eV after including systematic uncertainties; its stability across datasets proves its interstellar origin. The most recent high-resolution SII absorption template, however, only fits after a +7 to 8 eV energy-scale shift, comparable to the spread among different atomic calculations, so the paper argues that published SII cross-sections need systematic energy correction. In GX 340+0, a 300 ks XRISM exposure reveals residual absorption that the atomic template cannot explain; templates for troilite, pyrrhotite, and pyrite fit the residuals equally well and yield the same solid sulfur column, allowing the authors to combine gas and solid measurements into the first direct measurement of sulfur depletion, 40%$\\pm$15%. This also caps the fraction of interstellar iron in Fe-S compounds at <25%, consistent with earlier Fe L-shell studies.","pith_inferences":["If the +7 to 8 eV shift is confirmed by laboratory measurements, similar systematic energy-scale offsets may be present in theoretical cross-sections for other K-shell ions, so re-analysis of archival X-ray spectra could reveal previously missed interstellar lines.","The paper's three Fe-S templates cannot be distinguished, which suggests sulfur K-shell X-ray absorption alone has limited sensitivity to the iron coordination environment; combining S K-edge with Fe L-edge absorption in the same sightline could break the degeneracy.","The 40% depletion value being obtained at roughly 11 kpc on opposite sides of the Galactic disk strengthens the case for extending this method to a larger sample of obscured X-ray binaries; if the value holds, Galactic chemical evolution models must allocate about 40% of interstellar sulfur to dust.","A direct test of the dust attribution would be a laboratory measurement of SII K-shell absorption with accurate energy calibration; if the cross-section's higher-order lines shift differently from K$\\beta$, the residual near 2.485 keV could be atomic rather than solid sulfur."],"forward_implications":["The SII K$\\beta$ resonance at 2470.8 eV becomes a fixed observational anchor for calibrating sulfur K-shell atomic models; future templates should reproduce it.","Sulfur depletion in the diffuse interstellar medium can now be measured directly from X-ray spectra, without relying on saturated ultraviolet lines or assumed abundance tables.","The 40%$\\pm$15% depletion in GX 340+0, combined with the similar sightline to 4U 1630-472, implies that a substantial fraction of Milky Way sulfur is in solid form even along these low-density sightlines.","The <25% upper limit on iron in Fe-S compounds means most refractory iron must reside in other phases, such as oxides or silicates, which constrains models of interstellar grain mineralogy.","The observed +7 to 8 eV shift in the SII template indicates that current atomic cross-sections misplace sulfur resonances; correcting them may affect abundance measurements of sulfur and other elements in earlier and future X-ray studies."],"supporting_citations":[{"why":"Supplies the state-of-the-art SII absorption cross-section template that the paper fits with a +7 to 8 eV energy shift and uses for the gas-phase abundance.","marker":"Gatuzz et al. (2024)"},{"why":"Provides the pseudo-relativistic Hartree-Fock predictions for SII K$\\beta$ line positions and the Einstein A coefficients used in the Voigt-profile column density measurement.","marker":"Palmeri et al. (2008)"},{"why":"Offers the alternative R-matrix SII cross-section calculation whose K$\\beta$ position differs from other predictions, supporting the paper's claim of 5 to 10 eV theoretical uncertainty.","marker":"Witthoeft et al. (2011)"},{"why":"Provides the troilite, pyrrhotite, and pyrite absorption cross-section templates used to fit the residual solid-sulfur absorption in GX 340+0.","marker":"Costantini et al. (2019)"},{"why":"Supplies the ISM absorption model and abundance table used to fit the continuum and to convert sulfur columns into implied hydrogen columns.","marker":"Wilms et al. (2000)"},{"why":"Establishes the 11.5 kpc distance and molecular cloud hydrogen column for 4U 1630-472 through dust-scattering ring analysis, supporting the interstellar interpretation.","marker":"Kalemci et al. (2018)"},{"why":"Provides the prior UV-based sulfur depletion measurements and depletion scale that the paper compares its 40% result against.","marker":"Jenkins (2009)"},{"why":"Gives a previous 40% sulfur depletion estimate for another sightline, which the paper cites as consistent with its direct X-ray measurement.","marker":"Psaradaki et al. (2024)"}],"fun_headline_variants":["XRISM direct measurement: 40% of ISM sulfur sits in dust","Sightline census: gas and solid sulfur, depletion 40±15%","SII K-beta at 2470.8 eV; solid sulfur detected via XRISM","Dust sulfur weighed: 40% depleted, Fe-S compounds under 25%"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The argument assumes that the residual absorption left after subtracting the shifted atomic SII template is really solid sulfur dust, and that troilite, pyrrhotite, and pyrite are the only relevant dust templates; if the atomic sulfur cross-section is wrong in its relative line strengths or has an energy-dependent shift, the dust detection and the 40% depletion fraction would not hold.","fun_headline_variants_meta":{"raw":{"variants":["XRISM direct measurement: 40% of ISM sulfur sits in dust","Sightline census: gas and solid sulfur, depletion 40±15%","SII K-beta at 2470.8 eV; solid sulfur detected via XRISM","Dust sulfur weighed: 40% depleted, Fe-S compounds under 25%"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000262,"raw_usage":{"total_tokens":1699,"prompt_tokens":1147,"completion_tokens":552,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":763,"completion_tokens_details":{"reasoning_tokens":462}},"tokens_in":763,"tokens_out":552,"duration_ms":6644,"temperature":1.0,"reasoning_tokens":462,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-07T05:02:52.705859+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the SII K-shell photoabsorption cross-section in the laboratory, or compute it with a fully converged method that reproduces the observed K$\\beta$ position, then fit the XRISM spectrum of GX 340+0 with the corrected atomic template alone. If the residual near 2.485 keV disappears without any dust component, the solid-sulfur detection and the 40% depletion measurement are artifacts of the atomic template; if the residual persists, the dust identification stands. A second XRISM observation of another obscured X-ray binary at comparable signal-to-noise that fails to reproduce the same line position and residual pattern would also challenge the interstellar interpretation.","supporting_citations":[{"cited_title":"W., Hasoglu, M","cited_arxiv_id":null,"evidence_quote":"Supplies the state-of-the-art SII absorption cross-section template that the paper fits with a +7 to 8 eV energy shift and uses for the gas-phase abundance."},{"cited_title":"2008, ApJS, 177, 408,","cited_arxiv_id":null,"evidence_quote":"Provides the pseudo-relativistic Hartree-Fock predictions for SII K$\\beta$ line positions and the Einstein A coefficients used in the Voigt-profile column density measurement."},{"cited_title":"C., García, J., Kallman, T","cited_arxiv_id":null,"evidence_quote":"Offers the alternative R-matrix SII cross-section calculation whose K$\\beta$ position differs from other predictions, supporting the paper's claim of 5 to 10 eV theoretical uncertainty."},{"cited_title":"T., Rogantini, D., et al","cited_arxiv_id":null,"evidence_quote":"Provides the troilite, pyrrhotite, and pyrite absorption cross-section templates used to fit the residual solid-sulfur absorption in GX 340+0."},{"cited_title":"J., & Tomsick, J","cited_arxiv_id":null,"evidence_quote":"Establishes the 11.5 kpc distance and molecular cloud hydrogen column for 4U 1630-472 through dust-scattering ring analysis, supporting the interstellar interpretation."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the prior UV-based sulfur depletion measurements and depletion scale that the paper compares its 40% result against."},{"cited_title":"2024, AJ, 167, 217,","cited_arxiv_id":null,"evidence_quote":"Gives a previous 40% sulfur depletion estimate for another sightline, which the paper cites as consistent with its direct X-ray measurement."}],"review_version":1}