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arXiv · 2610.24330

Magnetic-field constraints for four magnetic cataclysmic variables from simultaneous continuum and cyclotron modeling

Jiamao Lin·Wenyuan Guo·Yongkang Sun·Chengyuan Li·Wen Hou
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Abstract

their fields are rarely measured because cyclotron humps must be separated from uncertain continua and assigned to discrete harmonics. We applied a simultaneous continuum-cyclotron analysis to four DESI/LAMOST magnetic-CV candidates. We fit a white dwarf atmospheric model, a hot-spot blackbody, and an isothermal constant-$Λ$ cyclotron component in one inverse-variance weighted model. Profiling chi-square over the field strength exposes competing harmonic assignments, which we report as multiple acceptable branches when necessary, and posterior sampling gives branch-conditional uncertainties. We validated the field recovery on EQ Cet, BS Tri, and three SDSS polars, searched 6-7 yr of ZTF photometry for periods and aliases, and used archival UV-to-mid-infrared photometry to bound the donors. The fit gives one robust field, $B = 56.8\pm1.5$ MG, for J0005+2941. J0022+1340 has two indistinguishable branches at $B \simeq 64.4$ and 77.7 MG; J0749+3654 has competitive solutions near 29.3 and 96.4 MG; and J0035+4333 yields an indicative broad minimum at $B = 51.1\pm1.4$ MG. The ZTF data give 105.349 min for J0005+2941, with a narrow eclipse-like minimum, making it a rare eclipsing-polar candidate below the period gap; 80.4062 min for J0749+3654 from double-humped cyclotron beaming; and 143.8 min for J0035+4333. Strong He II 4686 in J0022+1340 and J0035+4333 and flat-to-inverted Balmer decrements in all four support magnetically channeled accretion. Archival mid-infrared photometry excludes donors earlier than about M4.5-M5 V in three systems and M3 V in J0035+4333. Joint continuum-cyclotron fitting gives secure fields when the humps are well resolved and explicit branch constraints otherwise.

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Jiamao Lin, Wenyuan Guo, Yongkang Sun, Chengyuan Li, Wen Hou. 2026-10-16. Magnetic-field constraints for four magnetic cataclysmic variables from simultaneous continuum and cyclotron modeling. https://arxiv.org/abs/2610.24330

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