SWIFT J1756.9−2508: spectral and timing properties of its 2018 outburst

Sanna, A.; Pintore, Fabio; Riggio, A.; Mazzola, S. M.; Bozzo, E.; Salvo, T. Di; Ferrigno, C.; Gambino, A. F.; Papitto, A.; Iaria, R.; Burderi, L.

doi:10.1093/mnras/sty2316

Cited by 20 publications

(18 citation statements)

References 42 publications

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“…In fact, the electron cross section and the resulting Compton optical depth decrease at high energies, allowing a larger fraction of the pulsed harder X-rays to reach the observer un-scattered. Note that a trend of increasing pulsed fraction with energy, albeit already at softer X-rays, was observed by other missions (e.g., RXTE, XMM-Newton and NuSTAR) also from SAX J1748.9−2021 (Patruno et al, 2009;Sanna et al, 2016), Swift J1756.9−2508 (Patruno et al, 2010;Sanna et al, 2018d) and, to a lesser extent, Swift J1749.4−2807 (Ferrigno et al, 2011).…”

Section: The Hard X-ray Pulse Profilesmentioning

confidence: 71%

The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars

Papitto¹,

Falanga

Hermsen

et al. 2020

New Astronomy Reviews

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In the last 25 years, a new generation of X-ray satellites imparted a significant leap forward in our knowledge of X-ray pulsars. The discovery of accreting and transitional millisecond pulsars proved that disk accretion can spin up a neutron star to a very high rotation speed. The detection of MeV-GeV pulsed emission from a few hundreds of rotation-powered pulsars probed particle acceleration in the outer magnetosphere, or even beyond. Also, a population of two dozens of magnetars has emerged. INTEGRAL played a central role to achieve these results by providing instruments with high temporal resolution up to the hard X-ray/soft γ-ray band and a large field of view imager with good angular resolution to spot hard X-ray transients. In this article, we review the main contributions by INTEGRAL to our understanding of the pulsating hard X-ray sky, such as the discovery and characterization of several accreting and transitional millisecond pulsars, the generation of the first catalog of hard X-ray/soft γ-ray rotation-powered pulsars, the detection of polarization in the hard X-ray emission from the Crab pulsar, and the discovery of persistent hard X-ray emission from several magnetars.

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Section: The Hard X-ray Pulse Profilesmentioning

confidence: 71%

The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars

Papitto¹,

Falanga

Hermsen

et al. 2020

New Astronomy Reviews

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“…This component of the spectrum introduces an additional stochastic noise which has a complex shape in the power spectra (see, e.g. Sanna et al 2018). In order to reduce the impact of this noise in our data we applied additional filtering criterion to the NICER data, following Bult et al (2018).…”

Section: Nicer Datamentioning

confidence: 99%

Observational constraints on the magnetic field of the bright transient Be/X-ray pulsar SXP 4.78

Семена

Lutovinov

Mereminskiy

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report results of the spectral and timing analysis of the Be/X-ray pulsar SXP 4.78 using the data obtained during its recent outburst with NuSTAR, Swift, Chandra and NICER observatories. Using an overall evolution of the system luminosity, spectral analysis and variability power spectrum we obtain constraints on the neutron star magnetic field strength. We found a rapid evolution of the variability power spectrum during the rise of the outburst, and absence of the significant changes during the flux decay. Several low frequency quasi-periodic oscillation features are found to emerge on the different stages of the outburst, but no clear clues on their origin were found in the energy spectrum and overall flux behaviour. We use several indirect methods to estimate the magnetic field strength on the neutron star surface and found that most of them suggest magnetic field B 2 × 10 12 G. The strictest upper limit comes from the absence of the cyclotron absorption features in the energy spectra and suggests relatively weak magnetic field B < 6 × 10 11 G.

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Section: Introductionmentioning

confidence: 99%

“…2018 (Sanna et al 2018c;Bult et al 2018a;Rai & Paul 2019;Chakraborty & Bhattacharyya 2018) and 2019 (Sanna et al 2019). During the first three recurrent outbursts from 2007 to 2018, the orbital period variation has not been detected (Krimm et al 2007b;Patruno et al 2010;Bult et al 2018a;Sanna et al 2018c). Moreover, the upper limit on the orbital period derivative is | Ṗorb | < 7.4 × 10 −13 s s −1 from the total 11 years span of the observations, consistent with the prediction of a conservative mass transfer in the binary system (Bult et al 2018a).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the upper limit on the orbital period derivative is | Ṗorb | < 7.4 × 10 −13 s s −1 from the total 11 years span of the observations, consistent with the prediction of a conservative mass transfer in the binary system (Bult et al 2018a). Swift J1756.9−2508 showed long term spin-down behavior with a spin frequency derivative of |ν| 3 × 10 −13 Hz s −1 measured by Patruno et al (2010), |ν| ∼ 7.3 × 10 −16 Hz s −1 by Bult et al (2018a) and a smaller value |ν| ∼ 4.8 × 10 −16 Hz s −1 by Sanna et al (2018c). Assuming that the rotational energy loss due to the magnetic dipole emission dominated the spin evolution of Swift J1756.9−2508, the magnetic field strength at the stellar magnetic poles was constrained to the range (3 − 6) × 10 8 G (see, e.g., Patruno et al 2010;Bult et al 2018a;Sanna et al 2018c, and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.9$-$2508 during its 2018 and 2019 outbursts

Li,

Kuiper,

Falanga

et al. 2021

Preprint

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The accreting millisecond X-ray pulsar Swift J1756.9−2508 went into outburst in April 2018 and June 2019, 8.7 yr after the previous activity period. We investigated the temporal, timing and spectral properties of these two outbursts using data from NICER, XMM-Newton, NuSTAR, INTEGRAL, Swift and Insight-HXMT. The two outbursts exhibited similar broad-band spectra and X-ray pulse profiles. For the first time, we report the detection of the pulsed emission up to ∼ 100 keV observed by Insight-HXMT during the 2018 outburst. We also found the pulsation up to ∼ 60 keV observed by NICER and NuSTAR during the 2019 outburst. We performed a coherent timing analysis combining the data from two outbursts. The binary system is well described by a constant orbital period over a time span of ∼ 12 years. The time-averaged broad-band spectra are well fitted by an absorbed thermal Comptonization model compps in a slab geometry with the electron temperature kT e = 40-50 keV, Thomson optical depth τ ∼ 1.3, blackbody seed photon temperature kT bb,seed ∼0.7-0.8 keV and hydrogen column density of N H ∼ 4.2 × 10 22 cm −2 . We searched the available data for type-I (thermonuclear) X-ray bursts, but found none, which is unsurprising given the estimated low peak accretion rate (≈ 0.05 of the Eddington rate) and generally low expected burst rates for hydrogen-poor fuel. Based on the history of four outbursts to date, we estimate the long-term average accretion rate at roughly 5 × 10 −12 M yr −1 for an assumed distance of 8 kpc. The expected mass transfer rate driven by gravitational radiation in the binary implies the source can be no closer than 4 kpc. Swift J1756.9−2508 is the third low mass X-ray binary exhibiting "double" outbursts, separated by much shorter intervals than usual, and likely resulting from interruption of the accretion flow from the disk onto the neutron star. Such behavior may have important implications for the disk instability model.

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SWIFT J1756.9−2508: spectral and timing properties of its 2018 outburst

Cited by 20 publications

References 42 publications

The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars

The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars

Observational constraints on the magnetic field of the bright transient Be/X-ray pulsar SXP 4.78

Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.9$-$2508 during its 2018 and 2019 outbursts

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