NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1

L. Keek; Z. Arzoumanian; P. Bult; E. M. Cackett; D. Chakrabarty; J. Chenevez; A. C. Fabian; K. C. Gendreau; S. Guillot; T. Güver; J. Homan; G. K. Jaisawal; F. K. Lamb; R. M. Ludlam; S. Mahmoodifar; C. B. Markwardt; J. M. Miller; G. Prigozhin; Y. Soong; T. E. Strohmayer; M. T. Wolff

doi:10.3847/2041-8213/aab104

NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1

L. Keek, Z. Arzoumanian, P. Bult, E. M. Cackett, D. Chakrabarty, J. Chenevez, A. C. Fabian, K. C. Gendreau, S. Guillot, T. Güver, J. Homan, G. K. Jaisawal, F. K. Lamb, R. M. Ludlam, S. Mahmoodifar, C. B. Markwardt, J. M. Miller, G. Prigozhin, Y. Soong, T. E. StrohmayerM. T. Wolff

Physics

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Abstract

Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type-I X-ray bursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impact on the disk during one of the first X-ray burst observations with the Neutron Star Interior Composition Explorer (NICER) on the International Space Station. The burst is seen from Aql X-1 during the hard spectral state. In addition to thermal emission from the neutron star, the burst spectrum exhibits an excess of soft X-ray photons below 1 keV, where NICER's sensitivity peaks. We interpret the excess as a combination of reprocessing by the strongly photoionized disk and enhancement of the pre-burst persistent flux, possibly due to Poynting-Robertson drag or coronal reprocessing. This is the first such detection for a short sub-Eddington burst. As these bursts are observed frequently, NICER will be able to study how X-ray bursts affect the disk and corona for a range of accreting neutron star systems and disk states.

Original language	English (US)
Article number	L4
Journal	Astrophysical Journal Letters
Volume	855
Issue number	1
DOIs	https://doi.org/10.3847/2041-8213/aab104
State	Published - Mar 1 2018

Keywords

accretion, accretion disks
stars: individual (Aql X-1)
stars: neutron
X-rays: binaries
X-rays: bursts

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/2041-8213/aab104

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Keek, L., Arzoumanian, Z., Bult, P., Cackett, E. M., Chakrabarty, D., Chenevez, J., Fabian, A. C., Gendreau, K. C., Guillot, S., Güver, T., Homan, J., Jaisawal, G. K., Lamb, F. K., Ludlam, R. M., Mahmoodifar, S., Markwardt, C. B., Miller, J. M., Prigozhin, G., Soong, Y., ... Wolff, M. T. (2018). NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1. Astrophysical Journal Letters, 855(1), [L4]. https://doi.org/10.3847/2041-8213/aab104

Keek, L, Arzoumanian, Z, Bult, P, Cackett, EM, Chakrabarty, D, Chenevez, J, Fabian, AC, Gendreau, KC, Guillot, S, Güver, T, Homan, J, Jaisawal, GK, Lamb, FK, Ludlam, RM, Mahmoodifar, S, Markwardt, CB, Miller, JM, Prigozhin, G, Soong, Y, Strohmayer, TE & Wolff, MT 2018, 'NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1', Astrophysical Journal Letters, vol. 855, no. 1, L4. https://doi.org/10.3847/2041-8213/aab104

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title = "NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1",

abstract = "Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type-I X-ray bursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impact on the disk during one of the first X-ray burst observations with the Neutron Star Interior Composition Explorer (NICER) on the International Space Station. The burst is seen from Aql X-1 during the hard spectral state. In addition to thermal emission from the neutron star, the burst spectrum exhibits an excess of soft X-ray photons below 1 keV, where NICER's sensitivity peaks. We interpret the excess as a combination of reprocessing by the strongly photoionized disk and enhancement of the pre-burst persistent flux, possibly due to Poynting-Robertson drag or coronal reprocessing. This is the first such detection for a short sub-Eddington burst. As these bursts are observed frequently, NICER will be able to study how X-ray bursts affect the disk and corona for a range of accreting neutron star systems and disk states.",

keywords = "accretion, accretion disks, stars: individual (Aql X-1), stars: neutron, X-rays: binaries, X-rays: bursts",

author = "L. Keek and Z. Arzoumanian and P. Bult and Cackett, {E. M.} and D. Chakrabarty and J. Chenevez and Fabian, {A. C.} and Gendreau, {K. C.} and S. Guillot and T. G{\"u}ver and J. Homan and Jaisawal, {G. K.} and Lamb, {F. K.} and Ludlam, {R. M.} and S. Mahmoodifar and Markwardt, {C. B.} and Miller, {J. M.} and G. Prigozhin and Y. Soong and Strohmayer, {T. E.} and Wolff, {M. T.}",

note = "Funding Information: This work was supported by NASA through the NICER mission and the Astrophysics Explorers Program. It benefited from JINA CEE (NSF grant PHY-1430152). E.M.C. acknowledges NSF CAREER award AST-1351222. S.G. acknowledges CNES. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved.",

year = "2018",

month = mar,

day = "1",

doi = "10.3847/2041-8213/aab104",

language = "English (US)",

volume = "855",

journal = "Astrophysical Journal Letters",

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TY - JOUR

T1 - NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1

AU - Keek, L.

AU - Arzoumanian, Z.

AU - Bult, P.

AU - Cackett, E. M.

AU - Chakrabarty, D.

AU - Chenevez, J.

AU - Fabian, A. C.

AU - Gendreau, K. C.

AU - Guillot, S.

AU - Güver, T.

AU - Homan, J.

AU - Jaisawal, G. K.

AU - Lamb, F. K.

AU - Ludlam, R. M.

AU - Mahmoodifar, S.

AU - Markwardt, C. B.

AU - Miller, J. M.

AU - Prigozhin, G.

AU - Soong, Y.

AU - Strohmayer, T. E.

AU - Wolff, M. T.

N1 - Funding Information: This work was supported by NASA through the NICER mission and the Astrophysics Explorers Program. It benefited from JINA CEE (NSF grant PHY-1430152). E.M.C. acknowledges NSF CAREER award AST-1351222. S.G. acknowledges CNES. Publisher Copyright: © 2018. The American Astronomical Society. All rights reserved.

PY - 2018/3/1

Y1 - 2018/3/1

N2 - Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type-I X-ray bursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impact on the disk during one of the first X-ray burst observations with the Neutron Star Interior Composition Explorer (NICER) on the International Space Station. The burst is seen from Aql X-1 during the hard spectral state. In addition to thermal emission from the neutron star, the burst spectrum exhibits an excess of soft X-ray photons below 1 keV, where NICER's sensitivity peaks. We interpret the excess as a combination of reprocessing by the strongly photoionized disk and enhancement of the pre-burst persistent flux, possibly due to Poynting-Robertson drag or coronal reprocessing. This is the first such detection for a short sub-Eddington burst. As these bursts are observed frequently, NICER will be able to study how X-ray bursts affect the disk and corona for a range of accreting neutron star systems and disk states.

AB - Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type-I X-ray bursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impact on the disk during one of the first X-ray burst observations with the Neutron Star Interior Composition Explorer (NICER) on the International Space Station. The burst is seen from Aql X-1 during the hard spectral state. In addition to thermal emission from the neutron star, the burst spectrum exhibits an excess of soft X-ray photons below 1 keV, where NICER's sensitivity peaks. We interpret the excess as a combination of reprocessing by the strongly photoionized disk and enhancement of the pre-burst persistent flux, possibly due to Poynting-Robertson drag or coronal reprocessing. This is the first such detection for a short sub-Eddington burst. As these bursts are observed frequently, NICER will be able to study how X-ray bursts affect the disk and corona for a range of accreting neutron star systems and disk states.

KW - accretion, accretion disks

KW - stars: individual (Aql X-1)

KW - stars: neutron

KW - X-rays: binaries

KW - X-rays: bursts

UR - http://www.scopus.com/inward/record.url?scp=85043451649&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85043451649&partnerID=8YFLogxK

U2 - 10.3847/2041-8213/aab104

DO - 10.3847/2041-8213/aab104

M3 - Article

AN - SCOPUS:85043451649

SN - 2041-8205

VL - 855

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L4

ER -

NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1

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