Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808

Tiziana Di Salvo, Rosario Iaria, Riggio, Bozzo, Rea, Sanna, Burderi, Papitto, Ferrigno

Risultato della ricerca: Article

15 Citazioni (Scopus)

Abstract

We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.3 min and a projected semi-major axis of 17.6 lt-ms. Based on the mass function, we estimate a minimum companion mass of 0.024 M⊙, which assumes a neutron star mass of 1.4 M⊙ and a maximum inclination angle of 75° (derived from the lack of eclipses and dips in the light-curve of the source). We find that the Roche-lobe of the companion star could either be filled by a hot (5 × 106 K) pure helium white dwarf with a 0.028 M⊙ mass (implying i ≃ 58°) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065 to 0.085 (16 < i < 21). During the outburst, the broad-band energy spectra are well described by a superposition of a weak black-body component (kT 0.5 keV) and a hard cut-off power-law with photon index Γ 1.7 and cut-off at a temperature kTe 130 keV. Up until the latest Swift-XRT observation performed on 19th July, 2016, the source had been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.
Lingua originaleEnglish
pagine (da-a)34-
Numero di pagine7
RivistaASTRONOMY &amp; ASTROPHYSICS
Volume598
Stato di pubblicazionePublished - 2017

Fingerprint

globular clusters
pulsars
outburst
x rays
cut-off
companion stars
eclipses
XMM-Newton telescope
lobes
newton
helium
neutron stars
light curve
inclination
metallicity
dip
power law
energy spectra
broadband
intervals

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cita questo

Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808. / Di Salvo, Tiziana; Iaria, Rosario; Riggio; Bozzo; Rea; Sanna; Burderi; Papitto; Ferrigno.

In: ASTRONOMY &amp; ASTROPHYSICS, Vol. 598, 2017, pag. 34-.

Risultato della ricerca: Article

Di Salvo, Tiziana ; Iaria, Rosario ; Riggio ; Bozzo ; Rea ; Sanna ; Burderi ; Papitto ; Ferrigno. / Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808. In: ASTRONOMY &amp; ASTROPHYSICS. 2017 ; Vol. 598. pagg. 34-.
@article{7d2ebdad836b4ed2a48378e213372a6c,
title = "Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808",
abstract = "We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.3 min and a projected semi-major axis of 17.6 lt-ms. Based on the mass function, we estimate a minimum companion mass of 0.024 M⊙, which assumes a neutron star mass of 1.4 M⊙ and a maximum inclination angle of 75° (derived from the lack of eclipses and dips in the light-curve of the source). We find that the Roche-lobe of the companion star could either be filled by a hot (5 × 106 K) pure helium white dwarf with a 0.028 M⊙ mass (implying i ≃ 58°) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065 to 0.085 (16 < i < 21). During the outburst, the broad-band energy spectra are well described by a superposition of a weak black-body component (kT 0.5 keV) and a hard cut-off power-law with photon index Γ 1.7 and cut-off at a temperature kTe 130 keV. Up until the latest Swift-XRT observation performed on 19th July, 2016, the source had been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.",
author = "{Di Salvo}, Tiziana and Rosario Iaria and Riggio and Bozzo and Rea and Sanna and Burderi and Papitto and Ferrigno",
year = "2017",
language = "English",
volume = "598",
pages = "34--",
journal = "ASTRONOMY &amp; ASTROPHYSICS",
issn = "0004-6361",

}

TY - JOUR

T1 - Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808

AU - Di Salvo, Tiziana

AU - Iaria, Rosario

AU - Riggio, null

AU - Bozzo, null

AU - Rea, null

AU - Sanna, null

AU - Burderi, null

AU - Papitto, null

AU - Ferrigno, null

PY - 2017

Y1 - 2017

N2 - We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.3 min and a projected semi-major axis of 17.6 lt-ms. Based on the mass function, we estimate a minimum companion mass of 0.024 M⊙, which assumes a neutron star mass of 1.4 M⊙ and a maximum inclination angle of 75° (derived from the lack of eclipses and dips in the light-curve of the source). We find that the Roche-lobe of the companion star could either be filled by a hot (5 × 106 K) pure helium white dwarf with a 0.028 M⊙ mass (implying i ≃ 58°) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065 to 0.085 (16 < i < 21). During the outburst, the broad-band energy spectra are well described by a superposition of a weak black-body component (kT 0.5 keV) and a hard cut-off power-law with photon index Γ 1.7 and cut-off at a temperature kTe 130 keV. Up until the latest Swift-XRT observation performed on 19th July, 2016, the source had been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.

AB - We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.3 min and a projected semi-major axis of 17.6 lt-ms. Based on the mass function, we estimate a minimum companion mass of 0.024 M⊙, which assumes a neutron star mass of 1.4 M⊙ and a maximum inclination angle of 75° (derived from the lack of eclipses and dips in the light-curve of the source). We find that the Roche-lobe of the companion star could either be filled by a hot (5 × 106 K) pure helium white dwarf with a 0.028 M⊙ mass (implying i ≃ 58°) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065 to 0.085 (16 < i < 21). During the outburst, the broad-band energy spectra are well described by a superposition of a weak black-body component (kT 0.5 keV) and a hard cut-off power-law with photon index Γ 1.7 and cut-off at a temperature kTe 130 keV. Up until the latest Swift-XRT observation performed on 19th July, 2016, the source had been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.

UR - http://hdl.handle.net/10447/228215

UR - http://adsabs.harvard.edu/abs/2017A%26A...598A..34S

M3 - Article

VL - 598

SP - 34-

JO - ASTRONOMY &amp; ASTROPHYSICS

JF - ASTRONOMY &amp; ASTROPHYSICS

SN - 0004-6361

ER -