Measuring a truncated disk in Aquila X-1

Ashley L. King; John A. Tomsick; Jon M. Miller; Jérôme Chenevez; Didier Barret; Steven E. Boggs; Deepto Chakrabarty; Finn Erland Christensen; William W. Craig; Felix Fürst; Charles J. Hailey; Fiona A. Harrison; Michael L. Parker; Daniel Stern; Patrizia Romano; Dominic J. Walton; William W. Zhang

doi:10.3847/2041-8205/819/2/L29

Measuring a truncated disk in Aquila X-1

Ashley L. King, John A. Tomsick, Jon M. Miller, Jérôme Chenevez, Didier Barret, Steven E. Boggs, Deepto Chakrabarty, Finn Erland Christensen, William W. Craig, Felix Fürst, Charles J. Hailey, Fiona A. Harrison, Michael L. Parker, Daniel Stern, Patrizia Romano, Dominic J. Walton, William W. Zhang

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Abstract

We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 ± 3R_G. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B<5 ± 2x10⁸. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.

Original language	English
Journal	The Astrophysical Journal Letters
Volume	819
Issue number	2
Pages (from-to)	L29
Number of pages	6
ISSN	2041-8205
DOIs	https://doi.org/10.3847/2041-8205/819/2/L29
Publication status	Published - 2016

Keywords

Accretion
Accretion disks
Magnetic fields
Stars: neutron
X-rays: binaries
X-rays: bursts

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Apjl 819 2 L29Final published version, 1.02 MB

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King, A. L., Tomsick, J. A., Miller, J. M., Chenevez, J., Barret, D., Boggs, S. E., Chakrabarty, D., Christensen, F. E., Craig, W. W., Fürst, F., Hailey, C. J., Harrison, F. A., Parker, M. L., Stern, D., Romano, P., Walton, D. J., & Zhang, W. W. (2016). Measuring a truncated disk in Aquila X-1. The Astrophysical Journal Letters, 819(2), L29. https://doi.org/10.3847/2041-8205/819/2/L29

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title = "Measuring a truncated disk in Aquila X-1",

abstract = "We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 ± 3RG. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B<5 ± 2x108. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.",

keywords = "Accretion, Accretion disks, Magnetic fields, Stars: neutron, X-rays: binaries, X-rays: bursts",

author = "King, {Ashley L.} and Tomsick, {John A.} and Miller, {Jon M.} and J{\'e}r{\^o}me Chenevez and Didier Barret and Boggs, {Steven E.} and Deepto Chakrabarty and Christensen, {Finn Erland} and Craig, {William W.} and Felix F{\"u}rst and Hailey, {Charles J.} and Harrison, {Fiona A.} and Parker, {Michael L.} and Daniel Stern and Patrizia Romano and Walton, {Dominic J.} and Zhang, {William W.}",

year = "2016",

doi = "10.3847/2041-8205/819/2/L29",

language = "English",

volume = "819",

pages = "L29",

journal = "The Astrophysical Journal Letters",

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TY - JOUR

T1 - Measuring a truncated disk in Aquila X-1

AU - King, Ashley L.

AU - Tomsick, John A.

AU - Miller, Jon M.

AU - Chenevez, Jérôme

AU - Barret, Didier

AU - Boggs, Steven E.

AU - Chakrabarty, Deepto

AU - Christensen, Finn Erland

AU - Craig, William W.

AU - Fürst, Felix

AU - Hailey, Charles J.

AU - Harrison, Fiona A.

AU - Parker, Michael L.

AU - Stern, Daniel

AU - Romano, Patrizia

AU - Walton, Dominic J.

AU - Zhang, William W.

PY - 2016

Y1 - 2016

N2 - We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 ± 3RG. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B<5 ± 2x108. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.

AB - We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 ± 3RG. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B<5 ± 2x108. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.

KW - Accretion

KW - Accretion disks

KW - Magnetic fields

KW - Stars: neutron

KW - X-rays: binaries

KW - X-rays: bursts

U2 - 10.3847/2041-8205/819/2/L29

DO - 10.3847/2041-8205/819/2/L29

M3 - Journal article

SN - 2041-8205

VL - 819

SP - L29

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

IS - 2

ER -

Measuring a truncated disk in Aquila X-1

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