A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658

Peter Bult; Gaurava K. Jaisawal; Tolga Güver; Tod E. Strohmayer; Diego Altamirano; Zaven Arzoumanian; David R. Ballantyne; Deepto Chakrabarty; Jérôme Chenevez; Keith C. Gendreau; Sebastien Guillot; Renee M. Ludlam

doi:10.3847/2041-8213/ab4ae1

A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658

Peter Bult, Gaurava K. Jaisawal, Tolga Güver, Tod E. Strohmayer, Diego Altamirano, Zaven Arzoumanian, David R. Ballantyne, Deepto Chakrabarty, Jérôme Chenevez, Keith C. Gendreau, Sebastien Guillot, Renee M. Ludlam

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Abstract

The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the 2019 August outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4–3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of (2.3 ± 0.1) × 10⁻⁷ erg s⁻¹ cm⁻², this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at 1.0 and 6.7 keV, and burst oscillations at the known pulsar spin frequency, with ≈4% fractional sinusoidal amplitude. We interpret the burst flux evolution as the detection of the local Eddington limits associated with the hydrogen and helium layers of the neutron star envelope. The emission lines are likely associated with Fe, due to reprocessing of the burst emission in the accretion disk.

Original language	English
Article number	L1
Journal	Astrophysical Journal Letters
Volume	885
Issue number	1
Number of pages	8
ISSN	2041-8205
DOIs	https://doi.org/10.3847/2041-8213/ab4ae1
Publication status	Published - 2019

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@article{e885b9be82c74b5a94d6eec30c8f605c,

title = "A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658",

abstract = "The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the 2019 August outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4–3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of (2.3 ± 0.1) × 10−7 erg s−1 cm−2, this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at 1.0 and 6.7 keV, and burst oscillations at the known pulsar spin frequency, with ≈4% fractional sinusoidal amplitude. We interpret the burst flux evolution as the detection of the local Eddington limits associated with the hydrogen and helium layers of the neutron star envelope. The emission lines are likely associated with Fe, due to reprocessing of the burst emission in the accretion disk.",

author = "Peter Bult and Jaisawal, {Gaurava K.} and Tolga G{\"u}ver and Strohmayer, {Tod E.} and Diego Altamirano and Zaven Arzoumanian and Ballantyne, {David R.} and Deepto Chakrabarty and J{\'e}r{\^o}me Chenevez and Gendreau, {Keith C.} and Sebastien Guillot and Ludlam, {Renee M.}",

year = "2019",

doi = "10.3847/2041-8213/ab4ae1",

language = "English",

volume = "885",

journal = "The Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "IOP Publishing",

number = "1",

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TY - JOUR

T1 - A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658

AU - Bult, Peter

AU - Jaisawal, Gaurava K.

AU - Güver, Tolga

AU - Strohmayer, Tod E.

AU - Altamirano, Diego

AU - Arzoumanian, Zaven

AU - Ballantyne, David R.

AU - Chakrabarty, Deepto

AU - Chenevez, Jérôme

AU - Gendreau, Keith C.

AU - Guillot, Sebastien

AU - Ludlam, Renee M.

PY - 2019

Y1 - 2019

N2 - The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the 2019 August outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4–3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of (2.3 ± 0.1) × 10−7 erg s−1 cm−2, this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at 1.0 and 6.7 keV, and burst oscillations at the known pulsar spin frequency, with ≈4% fractional sinusoidal amplitude. We interpret the burst flux evolution as the detection of the local Eddington limits associated with the hydrogen and helium layers of the neutron star envelope. The emission lines are likely associated with Fe, due to reprocessing of the burst emission in the accretion disk.

AB - The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the 2019 August outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4–3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of (2.3 ± 0.1) × 10−7 erg s−1 cm−2, this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at 1.0 and 6.7 keV, and burst oscillations at the known pulsar spin frequency, with ≈4% fractional sinusoidal amplitude. We interpret the burst flux evolution as the detection of the local Eddington limits associated with the hydrogen and helium layers of the neutron star envelope. The emission lines are likely associated with Fe, due to reprocessing of the burst emission in the accretion disk.

U2 - 10.3847/2041-8213/ab4ae1

DO - 10.3847/2041-8213/ab4ae1

M3 - Journal article

VL - 885

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 1

M1 - L1

ER -

A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658

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