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NICER discovery of millisecond x-ray pulsations and an ultracompact orbit in IGR J17494-3030

NICER discovery of millisecond x-ray pulsations and an ultracompact orbit in IGR J17494-3030
NICER discovery of millisecond x-ray pulsations and an ultracompact orbit in IGR J17494-3030
We report the detection of 376.05 Hz (2.66 ms) coherent X-ray pulsations in NICER observations of a transient outburst of the low-mass X-ray binary IGR J17494−3030 in 2020 October/November. The system is an accreting millisecond X-ray pulsar in a 75-minute ultracompact binary. The mass donor is most likely a sime0.02 M⊙ finite-entropy white dwarf composed of He or C/O. The fractional rms pulsed amplitude is 7.4%, and the soft (1–3 keV) X-ray pulse profile contains a significant second harmonic. The pulsed amplitude and pulse phase lag (relative to our mean timing model) are energy dependent, each having a local maximum at 4 and 1.5 keV, respectively. We also recovered the X-ray pulsations in archival 2012 XMM-Newton observations, allowing us to measure a long-term pulsar spin-down rate of $\dot{\nu }=-2.1(7)\times {10}^{-14}$ Hz s−1 and to infer a pulsar surface dipole magnetic field strength of sime109 G. We show that the mass transfer in the binary is likely nonconservative, and we discuss various scenarios for mass loss from the system.
2041-8205
Ng, Mason
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Ray, Paul S.
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Bult, Peter
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Chakrabarty, Deepto
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Jaisawal, Gaurava K.
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Malacaria, Christian
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Altamirano, Diego
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Arzoumanian, Zaven
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Gendreau, Keith C.
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Güver, Tolga
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Kerr, Matthew
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Strohmayer, Tod E.
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Wadiasingh, Zorawar
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Wolff, Michael T.
bf1dbc0e-28c1-4b44-aa86-71111986c73b
Ng, Mason
1ea126a4-d65f-4ea4-a97b-dd8620d745e4
Ray, Paul S.
773c1940-2b53-4871-8176-c363521bb83f
Bult, Peter
73bd0a3d-c566-4046-86c9-31f6e6cdac07
Chakrabarty, Deepto
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Jaisawal, Gaurava K.
4d5dcd39-0881-426d-8ad7-f378238405ae
Malacaria, Christian
309a8f91-28a7-4365-b0a3-633171fc2e51
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Arzoumanian, Zaven
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Gendreau, Keith C.
289c5283-377f-476a-aec3-5532dfff6f2b
Güver, Tolga
964ab35f-1906-4711-a39c-12a4a44aec7d
Kerr, Matthew
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Strohmayer, Tod E.
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Wadiasingh, Zorawar
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Wolff, Michael T.
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Ng, Mason, Ray, Paul S., Bult, Peter, Chakrabarty, Deepto, Jaisawal, Gaurava K., Malacaria, Christian, Altamirano, Diego, Arzoumanian, Zaven, Gendreau, Keith C., Güver, Tolga, Kerr, Matthew, Strohmayer, Tod E., Wadiasingh, Zorawar and Wolff, Michael T. (2021) NICER discovery of millisecond x-ray pulsations and an ultracompact orbit in IGR J17494-3030. Astrophysical Journal Letters, 908 (1), [L15]. (doi:10.3847/2041-8213/abe1b4).

Record type: Article

Abstract

We report the detection of 376.05 Hz (2.66 ms) coherent X-ray pulsations in NICER observations of a transient outburst of the low-mass X-ray binary IGR J17494−3030 in 2020 October/November. The system is an accreting millisecond X-ray pulsar in a 75-minute ultracompact binary. The mass donor is most likely a sime0.02 M⊙ finite-entropy white dwarf composed of He or C/O. The fractional rms pulsed amplitude is 7.4%, and the soft (1–3 keV) X-ray pulse profile contains a significant second harmonic. The pulsed amplitude and pulse phase lag (relative to our mean timing model) are energy dependent, each having a local maximum at 4 and 1.5 keV, respectively. We also recovered the X-ray pulsations in archival 2012 XMM-Newton observations, allowing us to measure a long-term pulsar spin-down rate of $\dot{\nu }=-2.1(7)\times {10}^{-14}$ Hz s−1 and to infer a pulsar surface dipole magnetic field strength of sime109 G. We show that the mass transfer in the binary is likely nonconservative, and we discuss various scenarios for mass loss from the system.

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NICER discovery of millisecond x-ray pulsations and an ultracompact orbit in IGR J17494-3030 - Accepted Manuscript
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Accepted/In Press date: 31 January 2021
e-pub ahead of print date: 15 February 2021
Additional Information: arxiv is am

Identifiers

Local EPrints ID: 447851
URI: http://eprints.soton.ac.uk/id/eprint/447851
ISSN: 2041-8205
PURE UUID: d36a8ef0-ea90-4e49-b118-a3b8ac3f1f9d
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

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Date deposited: 24 Mar 2021 18:30
Last modified: 26 Nov 2021 05:40

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Contributors

Author: Mason Ng
Author: Paul S. Ray
Author: Peter Bult
Author: Deepto Chakrabarty
Author: Gaurava K. Jaisawal
Author: Christian Malacaria
Author: Zaven Arzoumanian
Author: Keith C. Gendreau
Author: Tolga Güver
Author: Matthew Kerr
Author: Tod E. Strohmayer
Author: Zorawar Wadiasingh
Author: Michael T. Wolff

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