On the Curious Pulsation Properties of the Accreting Millisecond Pulsar IGR J17379-3747

Peter Bult; Craig B. Markwardt; Diego Altamirano; Zaven Arzoumanian; Deepto Chakrabarty; Keith C. Gendreau; Sebastien Guillot; Gaurava K. Jaisawal; Paul S. Ray; Tod E. Strohmayer

doi:10.3847/1538-4357/ab1b26

On the Curious Pulsation Properties of the Accreting Millisecond Pulsar IGR J17379-3747

Peter Bult, Craig B. Markwardt, Diego Altamirano, Zaven Arzoumanian, Deepto Chakrabarty, Keith C. Gendreau, Sebastien Guillot, Gaurava K. Jaisawal, Paul S. Ray, Tod E. Strohmayer

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Abstract

We report on the Neutron Star Interior Composition Explorer (NICER) monitoring campaign of the 468 Hz accreting millisecond X-ray pulsar IGR J17379-3747. From a detailed spectral and timing analysis of the coherent pulsations we find that they show a strong energy dependence, with soft thermal emission lagging about 640 µs behind the hard, Comptonized emission. Additionally, we observe uncommonly large pulse fractions, with measured amplitudes in excess of 20% sinusoidal fractional amplitude across the NICER passband and fluctuations of up to similar to 70%. Based on a phase-resolved spectral analysis, we suggest that these extreme properties might be explained if the source has an unusually favorable viewing geometry with a large magnetic misalignment angle. Due to these large pulse fractions, we were able to detect pulsations down to quiescent luminosities (similar to 5 x 10³³ erg s^-1. We discuss these low-luminosity pulsations in the context of transitional millisecond pulsars.

Original language	English
Article number	70
Journal	Astrophysical Journal
Volume	877
Issue number	2
Number of pages	12
ISSN	0004-637X
DOIs	https://doi.org/10.3847/1538-4357/ab1b26
Publication status	Published - 2019

Keywords

Stars: neutron
X-rays: binaries
X-rays: individual (IGR J17379-3747)

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10.3847/1538-4357/ab1b26

Bult 2019 ApJ 877 70Final published version, 2.46 MB

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@article{cfdf323598334c2dbc2e6dffbaf54b71,

title = "On the Curious Pulsation Properties of the Accreting Millisecond Pulsar IGR J17379-3747",

abstract = "We report on the Neutron Star Interior Composition Explorer (NICER) monitoring campaign of the 468 Hz accreting millisecond X-ray pulsar IGR J17379-3747. From a detailed spectral and timing analysis of the coherent pulsations we find that they show a strong energy dependence, with soft thermal emission lagging about 640 µs behind the hard, Comptonized emission. Additionally, we observe uncommonly large pulse fractions, with measured amplitudes in excess of 20\% sinusoidal fractional amplitude across the NICER passband and fluctuations of up to similar to 70\%. Based on a phase-resolved spectral analysis, we suggest that these extreme properties might be explained if the source has an unusually favorable viewing geometry with a large magnetic misalignment angle. Due to these large pulse fractions, we were able to detect pulsations down to quiescent luminosities (similar to 5 x 1033 erg s-1. We discuss these low-luminosity pulsations in the context of transitional millisecond pulsars.",

keywords = "Stars: neutron, X-rays: binaries, X-rays: individual (IGR J17379-3747)",

author = "Peter Bult and Markwardt, \{Craig B.\} and Diego Altamirano and Zaven Arzoumanian and Deepto Chakrabarty and Gendreau, \{Keith C.\} and Sebastien Guillot and Jaisawal, \{Gaurava K.\} and Ray, \{Paul S.\} and Strohmayer, \{Tod E.\}",

year = "2019",

doi = "10.3847/1538-4357/ab1b26",

language = "English",

volume = "877",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

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TY - JOUR

T1 - On the Curious Pulsation Properties of the Accreting Millisecond Pulsar IGR J17379-3747

AU - Bult, Peter

AU - Markwardt, Craig B.

AU - Altamirano, Diego

AU - Arzoumanian, Zaven

AU - Chakrabarty, Deepto

AU - Gendreau, Keith C.

AU - Guillot, Sebastien

AU - Jaisawal, Gaurava K.

AU - Ray, Paul S.

AU - Strohmayer, Tod E.

PY - 2019

Y1 - 2019

N2 - We report on the Neutron Star Interior Composition Explorer (NICER) monitoring campaign of the 468 Hz accreting millisecond X-ray pulsar IGR J17379-3747. From a detailed spectral and timing analysis of the coherent pulsations we find that they show a strong energy dependence, with soft thermal emission lagging about 640 µs behind the hard, Comptonized emission. Additionally, we observe uncommonly large pulse fractions, with measured amplitudes in excess of 20% sinusoidal fractional amplitude across the NICER passband and fluctuations of up to similar to 70%. Based on a phase-resolved spectral analysis, we suggest that these extreme properties might be explained if the source has an unusually favorable viewing geometry with a large magnetic misalignment angle. Due to these large pulse fractions, we were able to detect pulsations down to quiescent luminosities (similar to 5 x 1033 erg s-1. We discuss these low-luminosity pulsations in the context of transitional millisecond pulsars.

AB - We report on the Neutron Star Interior Composition Explorer (NICER) monitoring campaign of the 468 Hz accreting millisecond X-ray pulsar IGR J17379-3747. From a detailed spectral and timing analysis of the coherent pulsations we find that they show a strong energy dependence, with soft thermal emission lagging about 640 µs behind the hard, Comptonized emission. Additionally, we observe uncommonly large pulse fractions, with measured amplitudes in excess of 20% sinusoidal fractional amplitude across the NICER passband and fluctuations of up to similar to 70%. Based on a phase-resolved spectral analysis, we suggest that these extreme properties might be explained if the source has an unusually favorable viewing geometry with a large magnetic misalignment angle. Due to these large pulse fractions, we were able to detect pulsations down to quiescent luminosities (similar to 5 x 1033 erg s-1. We discuss these low-luminosity pulsations in the context of transitional millisecond pulsars.

KW - Stars: neutron

KW - X-rays: binaries

KW - X-rays: individual (IGR J17379-3747)

U2 - 10.3847/1538-4357/ab1b26

DO - 10.3847/1538-4357/ab1b26

M3 - Journal article

SN - 0004-637X

VL - 877

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 70

ER -

On the Curious Pulsation Properties of the Accreting Millisecond Pulsar IGR J17379-3747

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Keywords

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