Cyclotron emitting magnetic white dwarfs in post common-envelope binaries discovered with the Zwicky Transient Facility

We present the discovery of 14 new (and the recovery of four known) low accretion rate magnetic white dwarfs in post-common envelope binaries that emit strong cyclotron emission using the Zwicky Transient Facility (ZTF) light curves, doubling the known sample size. In addition, we discovered a candidate magnetic period bouncer and recovered three known ones. We confirmed the presence of cyclotron emission using low-resolution spectra in 19 objects. Using the ZTF light curves, follow-up spectra, and the spectral energy distribution, we measured the orbital period, magnetic field strength, and white dwarf temperature of each system. Although the phase-folded light curves have diverse shapes and show a much larger variability amplitude, we show that their intrinsic properties (e.g. period distribution, magnetic field strength) are similar to those of previously known systems. The diversity in light curve shapes can be explained by differences in the optical depth of the accretion spot and geometric differences, the inclination angle, and the magnetic spot latitude. The evolutionary states of the longer period binaries are somewhat uncertain but vary; we found systems consistent with being pre-polars, detached polars, or low-state polars. In addition, we discovered two new low-state polars that likely have brown dwarf companions and could be magnetic period bouncers.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-03-07
DOI
https://doi.org/10.1051/0004-6361/202451945
Citations
6
Primary Topic
Pulsars and Gravitational Waves Research
Type
article
Field-Weighted Citation Impact
6.93

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article

Cyclotron emitting magnetic white dwarfs in post common-envelope binaries discovered with the Zwicky Transient Facility

Á. Rodríguez, A. Mahabal, G. Helou, J. Sollerman et al.
6 citations
Astronomy and Astrophysics
Pulsars and Gravitational Waves Research
6.93
article

Cyclotron emitting magnetic white dwarfs in post common-envelope binaries discovered with the Zwicky Transient Facility

Á. Rodríguez, A. Mahabal, G. Helou, J. Sollerman, Ilaria Caiazzo, Kareem J. El-Badry, Paula Szkody, R. Michael Rich, S. R. Kulkarni, A. Wold, Jan van Roestel, S.L. Groom, Eric C. Bellm, Alan Brown, Zachary P. Vanderbosch, M. L. Graham, Y. Sharma, R. Dekany, James D. Neill, F. Feinstein, T. Prince, A. J. Drake, T. du Laz
article en
6 citations

Abstract

We present the discovery of 14 new (and the recovery of four known) low accretion rate magnetic white dwarfs in post-common envelope binaries that emit strong cyclotron emission using the Zwicky Transient Facility (ZTF) light curves, doubling the known sample size. In addition, we discovered a candidate magnetic period bouncer and recovered three known ones. We confirmed the presence of cyclotron emission using low-resolution spectra in 19 objects. Using the ZTF light curves, follow-up spectra, and the spectral energy distribution, we measured the orbital period, magnetic field strength, and white dwarf temperature of each system. Although the phase-folded light curves have diverse shapes and show a much larger variability amplitude, we show that their intrinsic properties (e.g. period distribution, magnetic field strength) are similar to those of previously known systems. The diversity in light curve shapes can be explained by differences in the optical depth of the accretion spot and geometric differences, the inclination angle, and the magnetic spot latitude. The evolutionary states of the longer period binaries are somewhat uncertain but vary; we found systems consistent with being pre-polars, detached polars, or low-state polars. In addition, we discovered two new low-state polars that likely have brown dwarf companions and could be magnetic period bouncers.

Astronomy and AstrophysicsVol. 696
California Institute of Technology (US), University of California, Los Angeles (US), Stockholm University (SE), University of Washington (US), Aix-Marseille Université (FR), Astronomical Institute of the Slovak Academy of Sciences (SK), Infrared Processing and Analysis Center (US), Optica (US), University of Amsterdam (NL), Universitat Politècnica de Catalunya (ES)
National Science Foundation, National Aeronautics and Space Administration, W. M. Keck Foundation, California Institute of Technology, Northwestern University, Drexel University, University of Warwick, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Stockholms Universitet
Openalex Percentile: Top 4%
Pulsars and Gravitational Waves Research
6.93
DOIOpen Access PDFOpenAlex
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