{"id":"5ded9ddf-d866-4e89-8b30-6ce99d2badea","arxiv_id":"2505.14439","paper_version":3,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"The Pup Search reports one common proper motion confirmed and four candidate white dwarf companions to AFGK stars, plus two probable main sequence companions.","lead":"A new survey using the MagAO-X adaptive optics instrument found seven candidate companion stars near bright, Sun-like stars, five of which have the colors of white dwarfs. If the candidates are genuine companions, the survey opens a window on white dwarfs that hide in the glare of their host stars.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 'five new SLS' count rests on single-epoch detections whose physical association is unconfirmed, and the body itself flags HD 104018 cc1 as possibly a speckle or chance alignment.","rationale":"The reader's weakest assumption is exactly the load-bearing issue: the four single-epoch WD candidates are assumed to be physically bound and at the host's distance. I agree with that assessment and with the CONDITIONAL verdict. The paper is generally transparent—the body repeatedly uses 'candidate,' states the binding assumption in §3.1.2, and even admits for HD 104018 cc1 that it may be a speckle or chance alignment (§3.1.10). Those internal caveats show the authors are aware of the limitation, but the title and abstract present the four candidates as part of 'five new Sirius-Like systems,' which is not supported by the current data. The confirmed system TYC 4831-473-1 B is a genuine result, and the survey methodology, completeness analysis, and comparison to previous surveys are competently executed. The appropriate remedy is revision that rewords the title/abstract to distinguish one confirmed system from four candidates requiring follow-up, not rejection of the work. The concrete test—second-epoch astrometry—would settle the physical association for all four candidates and is a standard, feasible check. Since the reader already reached CONDITIONAL, my concern does not change the verdict.","tokens_in":27535,"tokens_out":4514,"duration_ms":43368,"concrete_test":"Acquire a second epoch (≥1 yr baseline) of MagAO-X imaging for BD+20 2007, BD-00 2082, TYC 1451-111-1, and HD 104018, reducing with the same pipeline and measuring relative astrometry. Compare each candidate's motion with the background track predicted from the host's Gaia proper motion and parallax, following the method used for TYC 4831-473-1 B in §3.1.3. If a candidate moves with the host (constant offset), it is bound and the distance/absolute-magnitude assumption holds; if it follows the background track or is absent in the second epoch, remove it from the 'new SLS' count. This directly tests the assumption stated in §3.1.2 and the paper's headline claim.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim—'five new Sirius-Like systems'—requires that all five WD candidates are physically bound to their AFGK hosts and therefore lie at the host's distance. Only TYC 4831-473-1 B has two epochs and is confirmed by common proper motion (§3.1.3). For the other four (BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, HD 104018 cc1), §3.1.2 explicitly assumes companionship: 'This procedure assumes the companion is bound to the primary, which we have only established for TYC 4831-473-1 B to date.' If any candidate is a background star or residual speckle, the Gaia-parallax-based absolute magnitudes and WD model fits of §3.1.2 and Figure 4 are invalid for that object. The risk is not hypothetical: HD 104018 cc1 is described in §3.1.10 as possibly 'not a true astrophysical signal' or 'a chance alignment,' with i'/z' S/N near 5 and no r' photometry; BD-00 2082 cc1 has z' S/N = 2.2. The abstract's 'five of which are confirmed to be white dwarfs' therefore overstates the support: photometric consistency with a WD model in two or three bands is not confirmation of a physical Sirius-like system. The one confirmed system is solid, but the survey's headline multiplicity is load-bearing and unsecured for the four candidates.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This manuscript reports the first results of the MagAO-X 'Pup Search' for white dwarf companions to AFGK stars. The authors present observations of 18 targets (Table 1 appears to list 19 unique targets), seven detected companion signals, photometry, spectral model fitting, survey completeness calculations, and comparisons with previous SLS surveys and Gaia-based detection metrics. They identify one system (TYC 4831-473-1 B) as a confirmed bound white dwarf via two epochs and common proper motion analysis, four additional white dwarf candidates from single-epoch imaging, one unresolved WD+M dwarf candidate, and one M dwarf companion. The central claim in the title and abstract is that five systems are 'confirmed' Sirius-like systems, which is stronger than the evidence presented in the body of the paper.","tokens_in":27778,"tokens_out":6232,"duration_ms":57557,"significance":"If the results are framed accurately, the survey demonstrates that MagAO-X can probe a parameter space—angular separations of ~0.2–1 arcsec and visible-band contrasts of ~1e-4 to 1e-3—that is complementary to previous SLS surveys and to Gaia-based multiplicity metrics. The completeness analysis with injection-recovery contrast curves, the careful handling of negative signal injection, and the placement of the survey in the context of Willems & Kolb (2004) and El-Badry (2024) are valuable and well executed. The one confirmed system, TYC 4831-473-1 B, is supported by common proper motion and a reasonable photometric fit to a hydrogen-dominated white dwarf model. However, the headline result as stated is not supported by the manuscript's own evidence, and the body text (Section 5) contradicts the title and abstract.","major_comments":[{"comment":"The abstract states that 'five of which are confirmed to be white dwarfs' and the title announces 'Five New Sirius-Like White Dwarf + Main Sequence Star Systems,' but the evidence in the paper supports only one confirmed system. Only TYC 4831-473-1 B has two epochs establishing common proper motion (Section 3.1.4). The other four WD candidates (BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, HD 104018 cc1) are single-epoch detections. Section 3.1.2 explicitly states that the absolute-magnitude and WD-model fitting 'assumes the companion is bound to the primary, which we have only established for TYC 4831-473-1 B to date.' The conclusion (Section 5) itself says 'one new confirmed Sirius-Like System' and 'four additional candidate SLS.' The title and abstract overstate the confirmation level and are internally inconsistent with the rest of the paper. Please revise the title and abstract to distinguish confirmed from candidate systems, or provide second-epoch astrometry for the four candidates.","section":"Title/Abstract and Section 5"},{"comment":"The white dwarf classification of the four candidate companions is conditional on the assumption that each candidate is physically bound to the primary and thus lies at the primary's distance. Section 3.1.2 uses the primary's Gaia parallax to convert measured fluxes to absolute magnitudes; if a candidate is a background star or a residual speckle, the resulting absolute magnitudes and the WD model fits in Figure 4 are invalid. The risk is concrete: BD-00 2082 cc1 has z' S/N = 2.2 (Table 2), and HD 104018 cc1 is detected only in i' and z' bands with S/N = 5.2 and 5.4, with the authors themselves noting that it may be 'not a true astrophysical signal' or 'a chance alignment' (Section 3.1.10). The phrase 'confirmed to be white dwarfs' in the abstract therefore requires either a second epoch establishing common proper motion for each candidate, or an alternative confirmation (e.g., spectroscopy) that does not rely on assumed companionship. Until then, these objects should be reported strictly as WD candidates.","section":"Section 3.1.2 and Table 2"},{"comment":"The predicted survey yield of '28±5 new SLS' is based on 'the same detection rate as in this paper (6/18),' but only one of those six detections is a confirmed SLS; the five other detections used in the rate include four unconfirmed WD candidates and one unresolved WD+M dwarf candidate. If any of these candidates turn out to be unassociated or non-astrophysical, the detection rate and the derived yield are not meaningful as a rate of SLS discovery. Please propagate the confirmation status into the rate used for the prediction, or clearly present the prediction as a candidate-based upper limit.","section":"Section 4.2"}],"minor_comments":[{"comment":"The text says the survey observed 3 targets in 2022 and 18 in 2024, implying 18 unique targets overall, but Table 1 lists 19 unique targets (with TYC 4831-473-1 and TYC 169-1942-1 each appearing at two epochs). Please reconcile the stated target count.","section":"Section 2.2 and Table 1"},{"comment":"The heading and caption refer to 'BD-00 2028,' while Table 1, Table 2, and Figure 4 use 'BD-00 2082.' Use a single consistent identifier throughout.","section":"Section 3.1.7 and Figure 3"},{"comment":"Section 3 states 'We detected six new candidate companions,' but Table 2 reports seven detections (TYC 4831-473-1 B, HD 92588 cc1, BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, HD 108738 cc1, HD 104018 cc1). Please correct the count to seven or clarify which detection is excluded.","section":"Section 3 and Table 2"},{"comment":"The sentence 'As shown in Figure 11, our current contrast limit probes all but the oldest white dwarf companions' is not directly illustrated by Figure 11, which shows the local WD luminosity function; the relevant contrast limit is indicated by the dashed grey line (b) in that figure. Please rephrase to make the connection explicit.","section":"Section 4.3"}],"recommendation":"major_revision","confidential_remarks":"The core observational work and the one confirmed system are sound, and the paper is a good fit for the journal. The main issue is that the title and abstract overstate the confirmation level, and the paper's own Section 5 contradicts them. This is fixable within the scope of the manuscript by reframing the results as one confirmed plus four candidates, and by propagating that distinction into the yield prediction. I recommend major revision rather than rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: this is a competent survey paper that finds one confirmed Sirius-like system and four good WD candidates, but the title and abstract say \"five new systems.\" The body is more careful than the packaging. That mismatch is the main thing to fix.\n\nWhat's genuinely new: first science use of MagAO-X visible extreme AO for a WD companion search, five new WD candidate companions around AFGK stars, one confirmed by common proper motion across two epochs (TYC 4831-473-1 B). The completeness analysis (Sec 3.2.2) is thoughtful, and the comparison to prior surveys (Zuckerman, H13, Noor) makes the case that this instrument opens a parameter space at small separations that other methods have missed. The reduction methods (RPS, KLIP ADI, RDI, negative injection, Mawet S/N) are standard and well described. The non-detection contrast curves and the completeness maps are useful products.\n\nThe soft spot is real but contained. The survey's headline count is load-bearing and rests on four single-epoch detections whose physical association is not yet established. The photometry classifies them as WD-like in color, but classification is not confirmation of a bound system. The body says as much in Sec 3.1.2 (\"assumes the companion is bound... only established for TYC 4831-473-1 B\") and in the conclusion they call them \"candidate SLS.\" But the abstract says \"five of which are confirmed to be white dwarfs\" — that's true only in the photometric-classification sense, and the title's \"Five New Sirius-Like Systems\" overstates it. Two of the candidates are thin: BD-00 2082 cc1 has z' S/N = 2.2, and HD 104018 cc1 has only i' and z' and the authors themselves float speckle or chance alignment. So the four candidates range from plausible to shaky. The fix is straightforward: change the title/abstract to one confirmed + four candidates, and report the low-S/N ones as tentative.\n\nI don't think there's a deeper flaw. The photometric model fitting, the parallax-based absolute magnitudes, and the completeness simulation are all appropriate. No circularity. The paper is honest about what it doesn't know.\n\nWho's this for? Anyone working on WD binaries, Sirius-like systems, or extreme AO survey methods. It deserves a serious referee — the one confirmed system plus the completeness framework are worth publishing. But I would not accept as-is; the framing has to be corrected, and the candidates need follow-up epochs before being called systems.","headline":"A careful survey with one confirmed Sirius-like system and four solid candidates, but the title and abstract oversell five confirmed systems.","tokens_in":28463,"tokens_out":2067,"would_cite":false,"duration_ms":21703,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A visible-light extreme adaptive optics survey finds one confirmed and four candidate white dwarf companions to Sun-like stars in a regime Gaia and earlier surveys cannot probe.","keywords":["white dwarfs","Sirius-like systems","extreme adaptive optics","high-contrast imaging","binary stars","common proper motion","UV excess","MagAO-X"],"falsifier":"Take a second epoch of images of BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, and HD 104018 cc1 after enough time that the host star's proper motion has shifted a stationary background object by several times the astrometric uncertainty: companions that move with the host are bound, while sources that remain fixed are background objects and must be removed from the tally.","tokens_in":27305,"feed_emoji":"🔭","tokens_out":15945,"duration_ms":142067,"temperature":0.7,"pith_summary":"Most white dwarfs known in binaries with ordinary stars orbit M dwarfs, because a white dwarf's ultraviolet-blue light stands out against a cool red star. Around hotter AFGK stars the dwarf is lost in the host's glare, and Sirius-like systems, meaning a white dwarf plus a non-interacting main-sequence star, appear in catalogs far less often than binary evolution predicts. The paper argues that an extreme adaptive optics instrument, a high-contrast camera that corrects atmospheric blur at very small angular scales, working at visible wavelengths where the contrast between a white dwarf and a Sun-like star is smallest, can recover the missing systems. Imaging 18 targets selected from a vetted UV-excess catalog, it reports one confirmed and four candidate white dwarf companions at projected separations of 26 to 124 au, plus a likely unresolved M dwarf plus white dwarf candidate and an M dwarf companion. If the same detection rate holds for the full 84-target list, the survey predicts 28 plus or minus 5 new Sirius-like systems.","feed_headline":"One confirmed, four candidate white dwarfs found near Sun-like stars","feed_subtitle":"They sit close enough to be hidden in stellar glare, but too faint for Gaia to see.","key_machinery":"The load-bearing instrument is MagAO-X, an extreme adaptive optics system optimized for visible wavelengths of 500 to 1000 nm, where the flux contrast between a white dwarf and an AFGK main-sequence host is orders of magnitude more favorable than at near-infrared wavelengths. Detection uses three point-spread-function removal strategies chosen per target: radial profile subtraction for wide, bright companions; Karhunen-Loeve image processing with angular differential imaging, a principal-component PSF subtraction method, for companions hidden in speckles; and reference differential imaging when sky rotation is insufficient. Photometry is calibrated against the host star as an in-frame reference, with significance estimated through a small-sample aperture signal-to-noise prescription suited to close separations, and negative signal injection for the faintest candidate, HD 104018 cc1. White-dwarf classification is carried by fitting hydrogen- and helium-atmosphere cooling models to r', i', z' photometry, with absolute magnitudes derived by placing each companion at the host's Gaia distance. For TYC 4831-473-1 B, companionship is established directly by common proper motion between the 2022 and 2024 epochs.","core_discovery":"On its own terms, the paper establishes that the Pup Search survey with MagAO-X on the 6.5 m Magellan Clay Telescope can resolve white dwarf companions to AFGK stars at angular separations of roughly 0.2 to 1.0 arcseconds and projected physical separations of 26 to 124 au. The single confirmed system, TYC 4831-473-1 B, is a hydrogen-atmosphere white dwarf 110 au from the Sun-like star TYC 4831-473-1; two epochs of astrometry show it moving with the host rather than with the background. Four further candidates, BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, and HD 104018 cc1, fall on the white dwarf sequence of the color-magnitude diagram and are best fit by hydrogen-dominated atmosphere models. The paper's central interpretive claim is that these objects sit in a parameter space that previous surveys, which mostly found systems at separations beyond about one arcsecond, and Gaia multiplicity diagnostics such as RUWE, proper motion anomaly, and astrometric orbits, cannot reach, so the observed shortage of Sirius-like systems reflects incompleteness of the searches, not a genuinely small population.","pith_inferences":["If the four single-epoch candidates are confirmed by proper motion, the implied frequency of white dwarf companions around AFGK stars at 20 to 150 au would move the observed Sirius-like system fraction closer to the 50 to 60 percent binary fraction predicted by evolution, strengthening the case that the missing white dwarfs are simply hidden in glare.","The systematic tendency for the resolved companions to fit cooler effective temperatures than the UV-excess predictions, for example 8500 to 17000 K versus 30000 K for TYC 4831-473-1 B, suggests some UV-selected WD plus AFGK candidates may host an additional unresolved hot component, or that the SED-based temperatures are biased; spectroscopy of the resolved white dwarfs would discriminate.","The survey's completeness models imply that non-detections around high-RUWE targets are most plausibly companions inside roughly 100 mas, and applying the same visible-light extreme adaptive optics method with a coronagraph should recover them and can be generalized to M-dwarf hosts where UV excess also betrays a white dwarf."],"forward_implications":["Completing the full 84-target Pup Search list at the observed 6 out of 18 detection rate should produce 28 plus or minus 5 new Sirius-like systems.","The five new systems occupy 26 to 124 au projected separations, the regime where non-interacting Sirius-like systems are expected from binary evolution, so filling that gap revises the observed Sirius-like system frequency toward evolutionary predictions.","Orbital monitoring of these pairs can test whether 10 to 100 au Sirius-like systems are highly eccentric, implying eccentricity evolution and enhanced scattering of planetesimals into the white dwarf, or nearly circular, implying little companion influence on pollution.","Upcoming coronagraph upgrades to MagAO-X, with inner working angles about ten times smaller, are expected to connect direct-imaging detections with radial-velocity and spectroscopy-discovered Sirius-like systems and to probe beyond the reach of Gaia."],"supporting_citations":[{"why":"Supplies the vetted catalog of 128 WD+AFGK UV-excess candidates with radial-velocity vetting and predicted white dwarf effective temperatures from which the 18 targets were drawn.","marker":"R20"},{"why":"Defines Sirius-like systems and documents their shortfall relative to binary evolution predictions, the population problem this survey addresses.","marker":"Holberg et al. 2013"},{"why":"Previous Sirius-like system imaging survey whose detection regime, mostly beyond about one arcsecond, is the comparison showing MagAO-X reaches closer separations.","marker":"Zuckerman (2014)"},{"why":"Gaia-based white dwarf plus main-sequence binary survey used as the comparison sample in the angular separation versus physical separation diagram.","marker":"Noor et al. (2024)"},{"why":"Instrument paper establishing MagAO-X's visible-wavelength high-contrast capabilities and close-in resolution used by the survey.","marker":"Males et al. (2022)"},{"why":"Provides the small-sample signal-to-noise formula used for candidate significance and injection-recovery contrast limits.","marker":"Mawet et al. (2014)"},{"why":"Hydrogen-atmosphere white dwarf model grid against which companion photometry is fitted for classification.","marker":"Tremblay et al. (2011)"},{"why":"Supplies the distances used to place companions on the absolute-magnitude color-magnitude diagram and to compute projected separations.","marker":"Bailer-Jones et al. 2021"},{"why":"Orbital-period distribution used to show the detected 20 to 130 au regime is where non-interacting Sirius-like systems are expected.","marker":"Willems & Kolb (2004)"},{"why":"Sensitivity map of Gaia multiplicity diagnostics showing the survey probes separations and mass regimes Gaia cannot reach.","marker":"El-Badry (2024)"}],"fun_headline_variants":["MagAO-X finds 5 hidden white dwarfs near Sun-like stars","Pup Search reveals white dwarfs lost in stellar glare","New survey spots five white dwarfs orbiting AFGK stars","Telescope trick uncovers 5 hidden white dwarfs","Close-in white dwarfs found hiding beside Sun-like stars"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the four unconfirmed candidates are physically bound to their host stars and lie at the host's distance, which is what turns their photometry into white-dwarf absolute magnitudes and projected separations; a background star or a different distance would drop that object from the Sirius-like-system count.","fun_headline_variants_meta":{"raw":{"variants":["MagAO-X finds 5 hidden white dwarfs near Sun-like stars","Pup Search reveals white dwarfs lost in stellar glare","New survey spots five white dwarfs orbiting AFGK stars","Telescope trick uncovers 5 hidden white dwarfs","Close-in white dwarfs found hiding beside Sun-like stars"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000127,"raw_usage":{"total_tokens":1142,"prompt_tokens":997,"completion_tokens":145,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":613,"completion_tokens_details":{"reasoning_tokens":70}},"tokens_in":613,"tokens_out":145,"duration_ms":2486,"temperature":1.0,"reasoning_tokens":70,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-07T15:33:27.974699+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Take a second epoch of images of BD+20 2007 cc1, BD-00 2082 cc1, TYC 1451-111-1 cc1, and HD 104018 cc1 after enough time that the host star's proper motion has shifted a stationary background object by several times the astrometric uncertainty: companions that move with the host are bound, while sources that remain fixed are background objects and must be removed from the tally.","supporting_citations":[{"cited_title":"2014, Astrophys","cited_arxiv_id":null,"evidence_quote":"Previous Sirius-like system imaging survey whose detection regime, mostly beyond about one arcsecond, is the comparison showing MagAO-X reaches closer separations."},{"cited_title":"T., Farihi, J., Hollands, M., & Toonen, S","cited_arxiv_id":null,"evidence_quote":"Gaia-based white dwarf plus main-sequence binary survey used as the comparison sample in the angular separation versus physical separation diagram."}],"review_version":1}