Rapid Evolution of the White Dwarf Pulsar AR Scorpii

Peter Garnavich; Stephen B. Potter; David A. H. Buckley; Anke van Dyk; Daniel Egbo; Colin Littlefield; Anousha Greiveldinger

doi:10.3847/2041-8213/ad0be7

The Astrophysical Journal Letters (Jan 2023)

Rapid Evolution of the White Dwarf Pulsar AR Scorpii

Peter Garnavich,
Stephen B. Potter,
David A. H. Buckley,
Anke van Dyk,
Daniel Egbo,
Colin Littlefield,
Anousha Greiveldinger

Affiliations

Peter Garnavich: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]
Stephen B. Potter: ORCiD; South African Astronomical Observatory , PO Box 9, Observatory 7935, Cape Town, South Africa; Department of Physics, University of Johannesburg , PO Box 524, 2006 Auckland Park, Johannesburg, South Africa
David A. H. Buckley: ORCiD; South African Astronomical Observatory , PO Box 9, Observatory 7935, Cape Town, South Africa; Department of Astronomy, University of Cape Town , Private Bag X3, Rondebosch 7701, South Africa; Department of Physics, University of the Free State , P.O. Box 339, Bloemfontein 9300, South Africa
Anke van Dyk: ORCiD; South African Astronomical Observatory , PO Box 9, Observatory 7935, Cape Town, South Africa; Department of Astronomy, University of Cape Town , Private Bag X3, Rondebosch 7701, South Africa
Daniel Egbo: ORCiD; South African Astronomical Observatory , PO Box 9, Observatory 7935, Cape Town, South Africa; Department of Astronomy, University of Cape Town , Private Bag X3, Rondebosch 7701, South Africa
Colin Littlefield: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]; Bay Area Environmental Research Institute , Moffett Field, CA 94035, USA
Anousha Greiveldinger: ORCiD; Department of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USA ; [email protected]

DOI: https://doi.org/10.3847/2041-8213/ad0be7
Journal volume & issue: Vol. 958, no. 2
p. L22

Abstract

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Analysis of AR Sco optical light curves spanning 9 yr shows a secular change in the relative amplitudes of the beat pulse pairs generated by the two magnetic poles of its rotating white dwarf. Recent photometry now shows that the primary and secondary beat pulses have similar amplitudes, while in 2015 the primary pulse was approximately twice that of the secondary peak. The equalization in the beat pulse amplitudes is also seen in the linearly polarized flux. This rapid evolution is consistent with precession of the white dwarf spin axis. The observations imply that the pulse amplitudes cycle over a period of ≳40 yr but that the upper limit is currently poorly constrained. If precession is the mechanism driving the evolution, then over the next 10 yr the ratio of the beat pulse amplitudes will reach a maximum followed by a return to asymmetric beat pulses.

Published in The Astrophysical Journal Letters

ISSN: 2041-8205 (Print); 2041-8213 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/2041-8205

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