A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability
Extremely low-mass (ELM) white dwarfs (WDs) are helium-core WDs with masses less than 0.3 M _⊙ . Short-period ELM WD binaries that exhibit ellipsoidal variations may harbor heavier companions, either massive WDs or millisecond pulsars (MSPs). In this study, we selected ∼12,000 ELM WDs or their candi...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9de5 |
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| author | W. J. Huang Pak-Hin Thomas Tam L. L. Ren J. M. Lin |
| author_facet | W. J. Huang Pak-Hin Thomas Tam L. L. Ren J. M. Lin |
| author_sort | W. J. Huang |
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| description | Extremely low-mass (ELM) white dwarfs (WDs) are helium-core WDs with masses less than 0.3 M _⊙ . Short-period ELM WD binaries that exhibit ellipsoidal variations may harbor heavier companions, either massive WDs or millisecond pulsars (MSPs). In this study, we selected ∼12,000 ELM WDs or their candidates, and searched for ellipsoidal-like lightcurves with orbital periods shorter than 1 day, by using the public data from Zwicky Transient Facility. Finally, 23 such systems were found, with 17 being newly discovered. We selected nine high-priority targets likely to evolve from the Roche lobe overflow channel and estimated their companion masses from the extracted ellipsoidal variation amplitude. Among them, four targets have companion masses exceeding 1 M _⊙ . We performed a search for radio pulsations from six of these targets by using Five-hundred-meter Aperture Spherical radio Telescope. However, no convincing radio pulse signals were found, resulting in upper limits for the radio flux at around 8 μ Jy. Given the nondetection of radio pulsations from a total of 11 similar systems, the fraction of ellipsoidal ELM WDs around MSPs is estimated to be below 15 ${}_{-3}^{+6}$ %. We anticipate that multiwavelength studies of more ellipsoidal-like ELM WDs will further constrain the fraction. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| spelling | doaj-art-b2f2efecd32247b3a5923b6a14693e582025-02-03T12:44:36ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198014610.3847/1538-4357/ad9de5A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal VariabilityW. J. Huang0https://orcid.org/0000-0001-5546-8549Pak-Hin Thomas Tam1https://orcid.org/0000-0002-1262-7375L. L. Ren2https://orcid.org/0000-0002-1428-4003J. M. Lin3https://orcid.org/0009-0008-9942-620XSchool of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People’s Republic of China ; tanbxuan@mail.sysu.edu.cnSchool of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People’s Republic of China ; tanbxuan@mail.sysu.edu.cnSchool of Electrical and Electronic Engineering, Anhui Science and Technology University , Bengbu, Anhui 233030, People’s Republic of ChinaSchool of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People’s Republic of China ; tanbxuan@mail.sysu.edu.cnExtremely low-mass (ELM) white dwarfs (WDs) are helium-core WDs with masses less than 0.3 M _⊙ . Short-period ELM WD binaries that exhibit ellipsoidal variations may harbor heavier companions, either massive WDs or millisecond pulsars (MSPs). In this study, we selected ∼12,000 ELM WDs or their candidates, and searched for ellipsoidal-like lightcurves with orbital periods shorter than 1 day, by using the public data from Zwicky Transient Facility. Finally, 23 such systems were found, with 17 being newly discovered. We selected nine high-priority targets likely to evolve from the Roche lobe overflow channel and estimated their companion masses from the extracted ellipsoidal variation amplitude. Among them, four targets have companion masses exceeding 1 M _⊙ . We performed a search for radio pulsations from six of these targets by using Five-hundred-meter Aperture Spherical radio Telescope. However, no convincing radio pulse signals were found, resulting in upper limits for the radio flux at around 8 μ Jy. Given the nondetection of radio pulsations from a total of 11 similar systems, the fraction of ellipsoidal ELM WDs around MSPs is estimated to be below 15 ${}_{-3}^{+6}$ %. We anticipate that multiwavelength studies of more ellipsoidal-like ELM WDs will further constrain the fraction.https://doi.org/10.3847/1538-4357/ad9de5White dwarf starsMillisecond pulsarsEllipsoidal variable starsClose binary stars |
| spellingShingle | W. J. Huang Pak-Hin Thomas Tam L. L. Ren J. M. Lin A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability The Astrophysical Journal White dwarf stars Millisecond pulsars Ellipsoidal variable stars Close binary stars |
| title | A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability |
| title_full | A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability |
| title_fullStr | A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability |
| title_full_unstemmed | A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability |
| title_short | A Search for Radio Millisecond Pulsar Companions around Extremely Low-mass White Dwarfs with Ellipsoidal Variability |
| title_sort | search for radio millisecond pulsar companions around extremely low mass white dwarfs with ellipsoidal variability |
| topic | White dwarf stars Millisecond pulsars Ellipsoidal variable stars Close binary stars |
| url | https://doi.org/10.3847/1538-4357/ad9de5 |
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