The false widow link between neutron star X-ray binaries and spider pulsars
The false widow link between neutron star X-ray binaries and spider pulsars
The discovery of transitional millisecond pulsars (tMSPs) provided conclusive proof that neutron star (NS) low-mass X-ray binaries (LMXBs) comprise part of the evolutionary pathway towards binary millisecond pulsars (MSPs). Redback and black widow ‘spider’ pulsars are a subcategory of binary MSPs that ‘devour’ their companions through ablation – the process through which material is lifted from the stellar surface by a pulsar wind. In addition to reducing the companion star’s mass, ablation introduces observable characteristics like extended, energy-dependent, and asymmetric eclipse profiles in systems observed at a sufficiently high inclination. Here, we present a detailed study and comparison of the X-ray eclipses of two NS LMXBs: Swift J1858.6 − 0814 and EXO 0748 − 676. Some of the X-ray eclipse characteristics observed in these two LMXBs are similar to the radio eclipse characteristics of eclipsing redback and black widow pulsars, suggesting that they may also host ablated companion stars. X-ray irradiation or a pulsar wind could drive the ablation. We conduct orbital phase-resolved spectroscopy for both LMXBs to map the column density, ionization, and covering fraction of the material outflow. From this, we infer the presence of highly ionized and clumpy ablated material around the companion star in both systems. We term LMXBs undergoing ablation, false widows, and speculate that they may be the progenitors of redback pulsars under the assumption that ablation begins in the LMXB stage. Therefore, the false widows could provide a link between LMXBs and spider pulsars. The detection of radio pulsations during non-accreting states can support this hypothesis.
3416-3435
Knight, Amy H.
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Ingram, Adam
01a02529-ad9f-4936-af5d-c200f88d4e53
Eijnden, Jakob van den
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Buisson, Douglas J.K.
f96b1210-d056-4948-9e4a-deeb669e6d1a
Rhodes, Lauren
bd150bed-04ba-4830-8930-c24276f87e9b
Middleton, Matthew
f91b89d9-fd2e-42ec-aa99-1249f08a52ad
3 February 2023
Knight, Amy H.
394b1ae4-038f-43d2-bb70-96d030ef2c6e
Ingram, Adam
01a02529-ad9f-4936-af5d-c200f88d4e53
Eijnden, Jakob van den
de845e38-fdcb-4c9e-a04e-59b5b4dfaebc
Buisson, Douglas J.K.
f96b1210-d056-4948-9e4a-deeb669e6d1a
Rhodes, Lauren
bd150bed-04ba-4830-8930-c24276f87e9b
Middleton, Matthew
f91b89d9-fd2e-42ec-aa99-1249f08a52ad
Knight, Amy H., Ingram, Adam, Eijnden, Jakob van den, Buisson, Douglas J.K., Rhodes, Lauren and Middleton, Matthew
(2023)
The false widow link between neutron star X-ray binaries and spider pulsars.
Monthly Notices of the Royal Astronomical Society, 520 (3), .
(doi:10.1093/mnras/stad383).
Abstract
The discovery of transitional millisecond pulsars (tMSPs) provided conclusive proof that neutron star (NS) low-mass X-ray binaries (LMXBs) comprise part of the evolutionary pathway towards binary millisecond pulsars (MSPs). Redback and black widow ‘spider’ pulsars are a subcategory of binary MSPs that ‘devour’ their companions through ablation – the process through which material is lifted from the stellar surface by a pulsar wind. In addition to reducing the companion star’s mass, ablation introduces observable characteristics like extended, energy-dependent, and asymmetric eclipse profiles in systems observed at a sufficiently high inclination. Here, we present a detailed study and comparison of the X-ray eclipses of two NS LMXBs: Swift J1858.6 − 0814 and EXO 0748 − 676. Some of the X-ray eclipse characteristics observed in these two LMXBs are similar to the radio eclipse characteristics of eclipsing redback and black widow pulsars, suggesting that they may also host ablated companion stars. X-ray irradiation or a pulsar wind could drive the ablation. We conduct orbital phase-resolved spectroscopy for both LMXBs to map the column density, ionization, and covering fraction of the material outflow. From this, we infer the presence of highly ionized and clumpy ablated material around the companion star in both systems. We term LMXBs undergoing ablation, false widows, and speculate that they may be the progenitors of redback pulsars under the assumption that ablation begins in the LMXB stage. Therefore, the false widows could provide a link between LMXBs and spider pulsars. The detection of radio pulsations during non-accreting states can support this hypothesis.
Text
2301.13864v1
- Author's Original
Text
stad383
- Version of Record
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Accepted/In Press date: 23 January 2023
Published date: 3 February 2023
Additional Information:
Funding Information:
AK acknowledges support from the Oxford Hintze Centre for Astrophysical Surveys, which is funded through generous support from the Hintze Family Charitable Foundation. AI acknowledges support from the Royal Society. JvdE is supported by a Lee Hysan Junior Research Fellowship awarded by St. Hilda’s College, Oxford. LR acknowledges support from STFC who has funded their research. This research has made use of software and data provided by the High Energy Astrophysics Science Archive Research Center (HEASARC) and the SAO/NASA Astrophysics Data System. The authors are grateful to the anonymous referee for a thorough and insightful report that prompted valuable changes to the manuscript.
Publisher Copyright:
© 2023 Oxford University Press. All rights reserved.
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Local EPrints ID: 478280
URI: http://eprints.soton.ac.uk/id/eprint/478280
ISSN: 1365-2966
PURE UUID: 6eccee41-5b66-4036-bfc5-b86f99baeb6a
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Date deposited: 27 Jun 2023 17:07
Last modified: 17 Mar 2024 03:05
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Author:
Amy H. Knight
Author:
Adam Ingram
Author:
Jakob van den Eijnden
Author:
Douglas J.K. Buisson
Author:
Lauren Rhodes
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