A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371

Carmela Galiano, Marco Matranga, Rosario Iaria, Tiziana Di Salvo, Riggio, Pintore, Sanna, Del Santo, Burderi, Ferrigno

Risultato della ricerca: Article

11 Citazioni (Scopus)

Abstract

Context. The source X1822-371 is a low-mass X-ray binary system (LMXB) viewed at a high inclination angle. It hosts a neutron star with a spin period of ∼0.59 s, and recently, the spin period derivative was estimated to be (-2.43 ± 0.05) × 10<sup>-12</sup> s/s. Aims. Our aim is to address the origin of the large residuals below 0.8 keV previously observed in the XMM/EPIC-pn spectrum of X1822-371. Methods. We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at ∼0.7 keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. Results. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, (8.8 ± 0.3) × 10<sup>10</sup> G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is (-2.55 ± 0.03) × 10<sup>-12</sup> s/s using all available pulse period measurements. Assuming that the intrinsic luminosity of X1822-371 is at the Eddington limit and using the values of spin period and spin period derivative of the source, we constrain the neutron star and companion star masses. We find the neutron star and the companion star masses to be 1.69 ± 0.13 M<inf>⊙</inf> and 0.46 ± 0.02 M<inf>⊙</inf>, respectively, for a neutron star radius of 10 km. Conclusions. In a self-consistent scenario in which X1822-371 is spinning-up and accretes at the Eddington limit, we estimate that the magnetic field of the neutron star is (8.8 ± 0.3) × 10<sup>10</sup> G for a neutron star radius of 10 km. If our interpretation is correct, the Gaussian absorption feature near 0.7 keV is the very first detection of a CRSF below 1 keV in a LMXB.
Lingua originaleEnglish
pagine (da-a)63-
Numero di pagine14
RivistaASTRONOMY &amp; ASTROPHYSICS
Volume577
Stato di pubblicazionePublished - 2015

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resonance scattering
cyclotron resonance
neutron stars
scattering
magnetic field
companion stars
XMM-Newton telescope
radii
cyclotrons
interstellar matter
x rays
estimates
pulses
magnetic fields
newton
metal spinning
inclination
energy
field strength
luminosity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371. / Galiano, Carmela; Matranga, Marco; Iaria, Rosario; Di Salvo, Tiziana; Riggio; Pintore; Sanna; Del Santo; Burderi; Ferrigno.

In: ASTRONOMY &amp; ASTROPHYSICS, Vol. 577, 2015, pag. 63-.

Risultato della ricerca: Article

@article{f7aa1cd0b67f44f2ae21f5ca3220fd7b,
title = "A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371",
abstract = "Context. The source X1822-371 is a low-mass X-ray binary system (LMXB) viewed at a high inclination angle. It hosts a neutron star with a spin period of ∼0.59 s, and recently, the spin period derivative was estimated to be (-2.43 ± 0.05) × 10-12 s/s. Aims. Our aim is to address the origin of the large residuals below 0.8 keV previously observed in the XMM/EPIC-pn spectrum of X1822-371. Methods. We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at ∼0.7 keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. Results. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, (8.8 ± 0.3) × 1010 G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is (-2.55 ± 0.03) × 10-12 s/s using all available pulse period measurements. Assuming that the intrinsic luminosity of X1822-371 is at the Eddington limit and using the values of spin period and spin period derivative of the source, we constrain the neutron star and companion star masses. We find the neutron star and the companion star masses to be 1.69 ± 0.13 M⊙ and 0.46 ± 0.02 M⊙, respectively, for a neutron star radius of 10 km. Conclusions. In a self-consistent scenario in which X1822-371 is spinning-up and accretes at the Eddington limit, we estimate that the magnetic field of the neutron star is (8.8 ± 0.3) × 1010 G for a neutron star radius of 10 km. If our interpretation is correct, the Gaussian absorption feature near 0.7 keV is the very first detection of a CRSF below 1 keV in a LMXB.",
author = "Carmela Galiano and Marco Matranga and Rosario Iaria and {Di Salvo}, Tiziana and Riggio and Pintore and Sanna and {Del Santo} and Burderi and Ferrigno",
year = "2015",
language = "English",
volume = "577",
pages = "63--",
journal = "ASTRONOMY &amp; ASTROPHYSICS",
issn = "0004-6361",

}

TY - JOUR

T1 - A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371

AU - Galiano, Carmela

AU - Matranga, Marco

AU - Iaria, Rosario

AU - Di Salvo, Tiziana

AU - Riggio, null

AU - Pintore, null

AU - Sanna, null

AU - Del Santo, null

AU - Burderi, null

AU - Ferrigno, null

PY - 2015

Y1 - 2015

N2 - Context. The source X1822-371 is a low-mass X-ray binary system (LMXB) viewed at a high inclination angle. It hosts a neutron star with a spin period of ∼0.59 s, and recently, the spin period derivative was estimated to be (-2.43 ± 0.05) × 10-12 s/s. Aims. Our aim is to address the origin of the large residuals below 0.8 keV previously observed in the XMM/EPIC-pn spectrum of X1822-371. Methods. We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at ∼0.7 keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. Results. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, (8.8 ± 0.3) × 1010 G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is (-2.55 ± 0.03) × 10-12 s/s using all available pulse period measurements. Assuming that the intrinsic luminosity of X1822-371 is at the Eddington limit and using the values of spin period and spin period derivative of the source, we constrain the neutron star and companion star masses. We find the neutron star and the companion star masses to be 1.69 ± 0.13 M⊙ and 0.46 ± 0.02 M⊙, respectively, for a neutron star radius of 10 km. Conclusions. In a self-consistent scenario in which X1822-371 is spinning-up and accretes at the Eddington limit, we estimate that the magnetic field of the neutron star is (8.8 ± 0.3) × 1010 G for a neutron star radius of 10 km. If our interpretation is correct, the Gaussian absorption feature near 0.7 keV is the very first detection of a CRSF below 1 keV in a LMXB.

AB - Context. The source X1822-371 is a low-mass X-ray binary system (LMXB) viewed at a high inclination angle. It hosts a neutron star with a spin period of ∼0.59 s, and recently, the spin period derivative was estimated to be (-2.43 ± 0.05) × 10-12 s/s. Aims. Our aim is to address the origin of the large residuals below 0.8 keV previously observed in the XMM/EPIC-pn spectrum of X1822-371. Methods. We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at ∼0.7 keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. Results. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, (8.8 ± 0.3) × 1010 G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is (-2.55 ± 0.03) × 10-12 s/s using all available pulse period measurements. Assuming that the intrinsic luminosity of X1822-371 is at the Eddington limit and using the values of spin period and spin period derivative of the source, we constrain the neutron star and companion star masses. We find the neutron star and the companion star masses to be 1.69 ± 0.13 M⊙ and 0.46 ± 0.02 M⊙, respectively, for a neutron star radius of 10 km. Conclusions. In a self-consistent scenario in which X1822-371 is spinning-up and accretes at the Eddington limit, we estimate that the magnetic field of the neutron star is (8.8 ± 0.3) × 1010 G for a neutron star radius of 10 km. If our interpretation is correct, the Gaussian absorption feature near 0.7 keV is the very first detection of a CRSF below 1 keV in a LMXB.

UR - http://hdl.handle.net/10447/153966

UR - http://www.edpsciences.org/journal/index.cfm?edpsname=aa

M3 - Article

VL - 577

SP - 63-

JO - ASTRONOMY &amp; ASTROPHYSICS

JF - ASTRONOMY &amp; ASTROPHYSICS

SN - 0004-6361

ER -