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An accreting white dwarf displaying fast transitional mode switching

An accreting white dwarf displaying fast transitional mode switching
An accreting white dwarf displaying fast transitional mode switching

Accreting white dwarfs are often found in close binary systems with orbital periods ranging from tens of minutes to several hours. In most cases, the accretion process is relatively steady, with significant modulations only occurring on timescales of ~days or longer 1,2. Here we report the discovery of abrupt drops in the optical luminosity of the accreting white dwarf binary system TW Pictoris by factors up to 3.5 on timescales as short as 30 minutes. The optical light curve of this binary system obtained by the Transiting Exoplanet Survey Satellite (TESS) clearly displays fast switches between two distinct intensity modes that probably track the changing mass accretion rate onto the white dwarf. In the low mode, the system also displays magnetically gated accretion bursts 3–5, which implies that a weak magnetic field of the white dwarf truncates the inner disc at the co-rotation radius in this mode. The properties of the mode switching observed in TW Pictoris appear analogous to those observed in transitional millisecond pulsars 6–10, where similar transitions occur, although on timescales of ~tens of seconds. Our discovery establishes a previously unrecognized phenomenon in accreting white dwarfs and suggests a tight link to the physics governing magnetic accretion onto neutron stars.

2397-3366
Scaringi, S.
88701970-a1b9-41fe-bf55-886716ee3374
Martino, D. de
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Buckley, D. H.
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Groot, P. J.
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Knigge, C.
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Fratta, M.
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Ilkiewicz, K.
0791e0ee-eaf2-4fa6-8156-a65a5a58672c
Littlefield, C.
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Papitto, A.
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Scaringi, S.
88701970-a1b9-41fe-bf55-886716ee3374
Martino, D. de
d918a7ed-1d6d-4fe3-b30e-917d14916ac0
Buckley, D. H.
2b82e4e2-d175-4cb3-9868-46b13f4f890c
Groot, P. J.
6e5c3d50-c4a7-4f4b-a136-c5f85080f7c1
Knigge, C.
ac320eec-631a-426e-b2db-717c8bf7857e
Fratta, M.
5dcc23b2-0d86-44df-9cbc-059a578f235d
Ilkiewicz, K.
0791e0ee-eaf2-4fa6-8156-a65a5a58672c
Littlefield, C.
5844d5fc-231e-44dd-ab6f-ace3c7f92db7
Papitto, A.
94920828-5e38-42a9-a9cc-3706b5136102

Scaringi, S., Martino, D. de, Buckley, D. H., Groot, P. J., Knigge, C., Fratta, M., Ilkiewicz, K., Littlefield, C. and Papitto, A. (2021) An accreting white dwarf displaying fast transitional mode switching. Nature Astronomy. (doi:10.1038/s41550-021-01494-x).

Record type: Letter

Abstract

Accreting white dwarfs are often found in close binary systems with orbital periods ranging from tens of minutes to several hours. In most cases, the accretion process is relatively steady, with significant modulations only occurring on timescales of ~days or longer 1,2. Here we report the discovery of abrupt drops in the optical luminosity of the accreting white dwarf binary system TW Pictoris by factors up to 3.5 on timescales as short as 30 minutes. The optical light curve of this binary system obtained by the Transiting Exoplanet Survey Satellite (TESS) clearly displays fast switches between two distinct intensity modes that probably track the changing mass accretion rate onto the white dwarf. In the low mode, the system also displays magnetically gated accretion bursts 3–5, which implies that a weak magnetic field of the white dwarf truncates the inner disc at the co-rotation radius in this mode. The properties of the mode switching observed in TW Pictoris appear analogous to those observed in transitional millisecond pulsars 6–10, where similar transitions occur, although on timescales of ~tens of seconds. Our discovery establishes a previously unrecognized phenomenon in accreting white dwarfs and suggests a tight link to the physics governing magnetic accretion onto neutron stars.

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2110.09124v1 - Accepted Manuscript
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Accepted/In Press date: 18 August 2021
e-pub ahead of print date: 18 October 2021
Published date: 18 October 2021

Identifiers

Local EPrints ID: 453311
URI: http://eprints.soton.ac.uk/id/eprint/453311
ISSN: 2397-3366
PURE UUID: 70afa845-7263-422b-8acc-811fcfc04fb4

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Date deposited: 12 Jan 2022 17:40
Last modified: 12 Jan 2022 17:40

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Contributors

Author: S. Scaringi
Author: D. de Martino
Author: D. H. Buckley
Author: P. J. Groot
Author: C. Knigge
Author: M. Fratta
Author: K. Ilkiewicz
Author: C. Littlefield
Author: A. Papitto

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