A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440

Tiziana Di Salvo, Rosario Iaria, Riggio, Bozzo, Pintore, Sanna, Sánchez-Fernández, Burderi, Mereghetti

Risultato della ricerca: Article

3 Citazioni (Scopus)

Abstract

SAX J1748.9-2021 is an accreting X-ray millisecond pulsar observed in outburst five times since its discovery in 1998. In early October 2017, the source started its sixth outburst, which lasted only ~13 days, significantly shorter than the typical 30 days duration of the previous outbursts. It reached a 0.3-70 keV unabsorbed peak luminosity of ~3 × 1036erg s-1. This is the weakest outburst ever reported for this source to date. We analysed almost simultaneous XMM-Newton, NuSTAR, and INTEGRAL observations taken during the decaying phase of its 2017 outburst. We found that the spectral properties of SAX J1748.9-2021 are consistent with an absorbed Comptonization plus a blackbody component. The former, characterized by an electron temperature of ~20 keV, a photon index of ~1.6-1.7 keV, and seed photon temperature of 0.44 keV, can be associated to a hot corona or the accretion column, while the latter is more likely originating from the neutron star surface (kTbb~ 0.6 keV, Rbb~ 2.5 km). These findings suggest that SAX J1748.9-2021 was observed in a hard spectral state, as it is typically the case for accreting millisecond pulsars in outburst. © 2018 The Author(s) Published by Oxford University Press on behalf of The Royal Astronomical Society.
Lingua originaleEnglish
pagine (da-a)4084-4090
Numero di pagine7
RivistaMonthly Notices of the Royal Astronomical Society
Volume479
Stato di pubblicazionePublished - 2018

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outburst
pulsars
photons
XMM-Newton telescope
newton
coronas
neutron stars
seeds
x rays
luminosity
electron energy
corona
temperature
accretion
seed
electron

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440. / Di Salvo, Tiziana; Iaria, Rosario; Riggio; Bozzo; Pintore; Sanna; Sánchez-Fernández; Burderi; Mereghetti.

In: Monthly Notices of the Royal Astronomical Society, Vol. 479, 2018, pag. 4084-4090.

Risultato della ricerca: Article

Di Salvo, T, Iaria, R, Riggio, Bozzo, Pintore, Sanna, Sánchez-Fernández, Burderi & Mereghetti 2018, 'A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440', Monthly Notices of the Royal Astronomical Society, vol. 479, pagg. 4084-4090.
Di Salvo, Tiziana ; Iaria, Rosario ; Riggio ; Bozzo ; Pintore ; Sanna ; Sánchez-Fernández ; Burderi ; Mereghetti. / A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440. In: Monthly Notices of the Royal Astronomical Society. 2018 ; Vol. 479. pagg. 4084-4090.
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title = "A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440",
abstract = "SAX J1748.9-2021 is an accreting X-ray millisecond pulsar observed in outburst five times since its discovery in 1998. In early October 2017, the source started its sixth outburst, which lasted only ~13 days, significantly shorter than the typical 30 days duration of the previous outbursts. It reached a 0.3-70 keV unabsorbed peak luminosity of ~3 × 1036erg s-1. This is the weakest outburst ever reported for this source to date. We analysed almost simultaneous XMM-Newton, NuSTAR, and INTEGRAL observations taken during the decaying phase of its 2017 outburst. We found that the spectral properties of SAX J1748.9-2021 are consistent with an absorbed Comptonization plus a blackbody component. The former, characterized by an electron temperature of ~20 keV, a photon index of ~1.6-1.7 keV, and seed photon temperature of 0.44 keV, can be associated to a hot corona or the accretion column, while the latter is more likely originating from the neutron star surface (kTbb~ 0.6 keV, Rbb~ 2.5 km). These findings suggest that SAX J1748.9-2021 was observed in a hard spectral state, as it is typically the case for accreting millisecond pulsars in outburst. {\circledC} 2018 The Author(s) Published by Oxford University Press on behalf of The Royal Astronomical Society.",
keywords = "Accretion, accretion discs; X-rays: binaries; X-Rays: galaxies -X-rays: individuals: SAX J1748.9-2021; Astronomy and Astrophysics; Space and Planetary Science",
author = "{Di Salvo}, Tiziana and Rosario Iaria and Riggio and Bozzo and Pintore and Sanna and S{\'a}nchez-Fern{\'a}ndez and Burderi and Mereghetti",
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TY - JOUR

T1 - A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440

AU - Di Salvo, Tiziana

AU - Iaria, Rosario

AU - Riggio, null

AU - Bozzo, null

AU - Pintore, null

AU - Sanna, null

AU - Sánchez-Fernández, null

AU - Burderi, null

AU - Mereghetti, null

PY - 2018

Y1 - 2018

N2 - SAX J1748.9-2021 is an accreting X-ray millisecond pulsar observed in outburst five times since its discovery in 1998. In early October 2017, the source started its sixth outburst, which lasted only ~13 days, significantly shorter than the typical 30 days duration of the previous outbursts. It reached a 0.3-70 keV unabsorbed peak luminosity of ~3 × 1036erg s-1. This is the weakest outburst ever reported for this source to date. We analysed almost simultaneous XMM-Newton, NuSTAR, and INTEGRAL observations taken during the decaying phase of its 2017 outburst. We found that the spectral properties of SAX J1748.9-2021 are consistent with an absorbed Comptonization plus a blackbody component. The former, characterized by an electron temperature of ~20 keV, a photon index of ~1.6-1.7 keV, and seed photon temperature of 0.44 keV, can be associated to a hot corona or the accretion column, while the latter is more likely originating from the neutron star surface (kTbb~ 0.6 keV, Rbb~ 2.5 km). These findings suggest that SAX J1748.9-2021 was observed in a hard spectral state, as it is typically the case for accreting millisecond pulsars in outburst. © 2018 The Author(s) Published by Oxford University Press on behalf of The Royal Astronomical Society.

AB - SAX J1748.9-2021 is an accreting X-ray millisecond pulsar observed in outburst five times since its discovery in 1998. In early October 2017, the source started its sixth outburst, which lasted only ~13 days, significantly shorter than the typical 30 days duration of the previous outbursts. It reached a 0.3-70 keV unabsorbed peak luminosity of ~3 × 1036erg s-1. This is the weakest outburst ever reported for this source to date. We analysed almost simultaneous XMM-Newton, NuSTAR, and INTEGRAL observations taken during the decaying phase of its 2017 outburst. We found that the spectral properties of SAX J1748.9-2021 are consistent with an absorbed Comptonization plus a blackbody component. The former, characterized by an electron temperature of ~20 keV, a photon index of ~1.6-1.7 keV, and seed photon temperature of 0.44 keV, can be associated to a hot corona or the accretion column, while the latter is more likely originating from the neutron star surface (kTbb~ 0.6 keV, Rbb~ 2.5 km). These findings suggest that SAX J1748.9-2021 was observed in a hard spectral state, as it is typically the case for accreting millisecond pulsars in outburst. © 2018 The Author(s) Published by Oxford University Press on behalf of The Royal Astronomical Society.

KW - Accretion

KW - accretion discs; X-rays: binaries; X-Rays: galaxies -X-rays: individuals: SAX J1748.9-2021; Astronomy and Astrophysics; Space and Planetary Science

UR - http://hdl.handle.net/10447/296909

UR - https://academic.oup.com/mnras/issue

M3 - Article

VL - 479

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EP - 4090

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

ER -