Observations of GRO J1744–28 in quiescence with <i>XMM-Newton</i>

Doroshenko, V.; Suleimanov, V.; Tsygankov, Sergey S.; Mönkkönen, Juhani; Ji, Long; Santangelo, A.

doi:10.1051/0004-6361/202038093

Cited by 11 publications

(6 citation statements)

References 48 publications

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“…Our detection of the CRSF thus strongly implies that the latter scenario is indeed correct, which is the first unambiguous evidence for the presence of the multipole fields in accreting neutron stars. We note that a similar scenario has been invoked for several other pulsing ultraluminous X-ray sources (pULXs) including SMC X-3 (Tsygankov et al 2017), GRO J1744-28 (Doroshenko et al 2020a), ULX M82 X-2 (Brice et al 2021), M51 ULX-8 (Middleton et al 2019), and others (Brice et al 2021). Our result unambiguously confirms that this scenario is indeed viable and certainly realized in at least one pulsating ULX (i.e., Swift J0243.6+6124).…”

Section: Discussionsupporting

confidence: 87%

Insight-HXMT discovery of the highest energy CRSF from the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Kong,

Zhang,

Zhang

et al. 2022

Preprint

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The detection of cyclotron resonance scattering features (CRSFs) is the only way to directly and reliably measure the magnetic field near the surface of a neutron star (NS). The broad energy coverage and large collection area of Insight-HXMT in the hard X-ray band allowed us to detect the CRSF with the highest energy known to date, reaching about 146 keV during the 2017 outburst of the first galactic pulsing ultraluminous X-ray source (pULX) Swift J0243.6+6124. During this outburst, the CRSF was only prominent close to the peak luminosity ∼ 2 × 10 39 erg s −1 , the highest to date in any of the Galactic pulsars. The CRSF is most significant in the spin phase region corresponding to the main pulse of the pulse profile, and its centroid energy evolves with phase from 120 to 146 keV. We identify this feature as the fundamental CRSF, since no spectral feature exists at 60 − 70 keV. This is the first unambiguous detection of an electron CRSF from an ULX. We also estimate a surface magnetic field ∼ 1.6 × 10 13 G for Swift J0243.6+6124. Considering that the dipole magnetic field strengths, inferred from several independent estimates of magnetosphere radius, are at least an order of magnitude lower than our measurement, we argue that the detection of the highest energy CRSF reported here unambiguously proves the presence of multipole field components close to the surface of the neutron star. Such a scenario has previously been suggested for several pulsating ULXs, including Swift J0243.6+6124, and our result represents the first direct confirmation of this scenario.

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Section: Discussionsupporting

confidence: 87%

Insight-HXMT discovery of the highest energy CRSF from the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Kong,

Zhang,

Zhang

et al. 2022

Preprint

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“…In our sample, two XRPs, Her X-1 and GRO J1744−28, stand out having a break frequency an order of magnitude higher than expected, beyond a combined effect of all the uncertainties. It is interesting to note that the presence of strong multipole field components has been suggested for both objects in the literature (Shakura et al 1991;Postnov et al 2013;Mönkkönen et al 2019;Doroshenko et al 2020b) based on multiple independent considerations. If that is indeed the case, one could expect to observe a reduced effective magnetosphere size (compared to the estimate for a dipole field) which could help to explain the observed high break frequency values.…”

Section: Discussionmentioning

confidence: 98%

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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“…This is achieved by simply summing up the power at each trial frequency with that of its m harmonics. This technique is known as the "Z m 2 periodogram" (Buccheri et al 1983), and it is widely used (e.g., Papa et al 2020;Doroshenko et al 2020;Takata et al 2021). 19 However, the phased lightcurve shape needed to choose an optimum value of m is typically unknown in advance.…”

Section: Context and Implicationsmentioning

confidence: 99%

1RXH J082623.6–505741: A New Long-period Cataclysmic Variable with an Evolved Donor and a Low Mass-transfer Rate

Sokolovsky

Strader

Swihart

et al. 2022

ApJ

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We report the discovery of 1RXH J082623.6−505741, a 10.4 hr orbital period compact binary. Modeling extensive optical photometry and spectroscopy reveals a ∼0.4 M ⊙ K-type secondary transferring mass through a low-state accretion disk to a nonmagnetic ∼0.8 M ⊙ white dwarf. The secondary is overluminous for its mass and dominates the optical spectra at all epochs and must be evolved to fill its Roche Lobe at this orbital period. The X-ray luminosity L X ∼ 1–2 × 1032 erg s−1 derived from both new XMM-Newton and archival observations, although high compared to most CVs, still only requires a modest accretion rate onto the white dwarf of M ̇ ∼ 3 × 10−11 to 3 × 10−10 M ⊙ yr−1, lower than expected for a cataclysmic variable with an evolved secondary. No dwarf nova outbursts have yet been observed from the system, consistent with the low derived mass-transfer rate. Several other cataclysmic variables with similar orbital periods also show unexpectedly low mass-transfer rates, even though selection effects disfavor the discovery of binaries with these properties. This suggests the abundance and evolutionary state of long-period, low mass-transfer rate cataclysmic variables are worthy of additional attention.

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Observations of GRO J1744–28 in quiescence with XMM-Newton

Cited by 11 publications

References 48 publications

Insight-HXMT discovery of the highest energy CRSF from the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Insight-HXMT discovery of the highest energy CRSF from the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

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

1RXH J082623.6–505741: A New Long-period Cataclysmic Variable with an Evolved Donor and a Low Mass-transfer Rate

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