Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Escorial, A. Rouco; Wijnands, Rudy; Ootes, L. S.; Degenaar, N.; Snelders, M. P.; Kaper, L.; Cackett, E.; Homan, J.

doi:10.1051/0004-6361/201834327

Cited by 11 publications

(10 citation statements)

References 63 publications

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“…The source was not detected on the average sky map with the 2σ upper limit comparable with the further Chandra detection (see Fig. 3 and recent paper of Rouco Escorial et al 2018 for studying of the low level state). This drastic change of the source luminosity is very similar to what observed recently with Swift/XRT in several other X-ray pulsars (Tsygankov et al 2016b;Lutovinov et al 2017) and most likely related to its transition to the propeller regime.…”

Section: Propeller Effectsupporting

confidence: 73%

GRO J1750–27: A neutron star far behind the Galactic Center switching into the propeller regime

Lutovinov

Tsygankov

Karasev

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report on analysis of properties of the X-ray binary pulsar GRO J1750−27 based on X-ray (Chandra, Swift, and Fermi/GBM), and near-infrared (VVV and UKIDSS surveys) observations. An accurate position of the source is determined for the first time and used to identify its infrared counterpart. Based on the VVV data we investigate the spectral energy distribution (SED) of the companion, taking into account a non-standard absorption law in the source direction. A comparison of this SED with those of known Be/X-ray binaries and early type stars has allowed us to estimate a lower distance limit to the source at > 12 kpc. An analysis of the observed spin-up torque during a giant outburst in 2015 provides an independent distance estimate of 14 − 22 kpc, and also allows to estimate the magnetic field on the surface of the neutron star at B ≃ (3.5 − 4.5) × 10 12 G. The latter value is in agreement with the possible transition to the propeller regime, a strong hint for which was revealed by Swift/XRT and Chandra. We conclude, that GRO J1750−27 is located far behind the Galactic Center, which makes it one of the furthest Galactic X-ray binaries known.

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Section: Propeller Effectsupporting

confidence: 73%

GRO J1750–27: A neutron star far behind the Galactic Center switching into the propeller regime

Lutovinov

Tsygankov

Karasev

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…The best-fitting returned NS blackbody temperatures of 1.1 ± 0.1 and 1.2 ± 0.1 keV with inferred emission radii of 12 ± 2 and 5 +2 −1 km for M1 and M2, respectively. The inferred small radii imply that emission originates from a smaller region of the NS surface/boundary layer (Rouco Escorial et al 2019). The discovery of narrow neutral iron emission line (𝜎 < 0.3 keV) implies that the emission line originates in a sparse and cold region, away from the NS.…”

Section: Discussionmentioning

confidence: 99%

Discovery of cyclotron and narrow Fe K$_α$ lines in HMXB GRO J1750-27

Sharma,

Jain,

Dutta

2022

Preprint

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We report on timing and spectral analysis of transient Be X-ray pulsar GRO J1750-27 using the Nuclear Spectroscopic Telescope Array (NuSTAR) observation from September 2021. This is the fourth outburst of the system since 1995. The NuSTAR observation was performed during the rising phase of the outburst. Pulsations at a period of 4.450710(1) s were observed in the 3-60 keV energy range. The average pulse profile comprised of a broad peak with a weak secondary peak which evolved with energy. We did not find any appreciable variation in the X-ray emission during this observation. The broad-band phase-averaged spectrum is described by a blackbody, a powerlaw or Comptonization component. We report discovery of Fe K 𝛼 line at 6.4 keV along with presence of two cyclotron resonant scattering features around 36 and 42 keV. These lines indicate a magnetic field strength of 3.7 +0.1 −0.3 × 10 12 and 4.4 ± 0.10 × 10 12 G for the neutron star. We have estimated a source distance of ∼ 13.6-16.4 kpc based on the accretion-disc torque models.

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“…The luminosities were calculated based on the distances to the sources reported in literature (Treuz et al 2018;Bailer-Jones et al 2018;Rouco Escorial et al 2019;Arnason et al 2021) and listed in Table 1, and fluxes derived from spectral analysis in this work for each observation. In particular, Standard2 spectra were modelled in the energy range of 3-50 keV.…”

Section: X-ray Pulsarsmentioning

confidence: 99%

Constraints on the magnetic field structure in accreting compact objects from aperiodic variability

Mönkkönen

Tsygankov

Mushtukov

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We investigate the aperiodic variability for a relatively large sample of accreting neutron stars and intermediate polars, focusing on the properties of the characteristic break commonly observed in power spectra of accreting objects. In particular, we investigate the relation of the break frequency and the magnetic field strength, both of which are connected to the size of the magnetosphere. We find that for the majority of objects in our sample the measured break frequency values indeed agree with estimated inner radii of the accretion disc, which allows to use observed break frequencies to independently assess the magnetic field strength and structure in accreting compact objects. As a special case, we focus on Hercules X-1 which is a persistent, medium-luminosity X-ray pulsar accreting from its low-mass companion. In the literature, it has been suggested that the complex pulse profiles, the spin-up behaviour and the luminosity-correlation of the cyclotron energy seen in Her X-1 can be explained with a complex magnetic field structure of the neutron star. Here, we connect the measured break frequency to the magnetospheric radius and show that the magnetic field strength derived assuming a dipole configuration is nearly an order of magnitude smaller than the magnetic field strength corresponding to the cyclotron energy. Accordingly, this discrepancy can be explained with the magnetic field having strong multipole components. The multipolar structure would also increase the accreting area on the neutron star surface, explaining why the critical luminosity for accretion column formation is puzzlingly high in this source.

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Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27

Cited by 11 publications

References 63 publications

GRO J1750–27: A neutron star far behind the Galactic Center switching into the propeller regime

GRO J1750–27: A neutron star far behind the Galactic Center switching into the propeller regime

Discovery of cyclotron and narrow Fe K$_α$ lines in HMXB GRO J1750-27

Constraints on the magnetic field structure in accreting compact objects from aperiodic variability

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