An XMM-Newton and NuSTAR Study of IGR J18214-1318: A Non-pulsating High-mass X-Ray Binary with a Neutron Star

Fornasini, Francesca M.; Tomsick, John A.; Bachetti, Matteo; Krivonos, R.; Fürst, Felix; Natalucci, L.; Pottschmidt, K.; Wilms, J.

doi:10.3847/1538-4357/aa6ff4

Cited by 17 publications

(24 citation statements)

References 109 publications

(147 reference statements)

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“…3.1 and also Carpano et al 2018), compared to E cut ∼20-30 keV observed in most nominal X-ray pulsars (e.g. White et al 1983;Di Salvo et al 1998;Coburn et al 2002;Miyasaka et al 2013;Fürst et al 2013Fürst et al , 2014Fornasini et al 2017) and also predicted by thermal and bulk comptonization models in the accretion column (e.g. Becker & Wolff 2007).…”

Section: Accretion Column Modelsupporting

confidence: 50%

Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1

Koliopanos

Vasilopoulos

Buchner

et al. 2019

A&A

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Aims. We investigate accretion models for the newly discovered pulsating ultraluminous X-ray source (ULX) NGC 300 ULX1 Methods. We analyzed broadband XMM-Newton and NuSTAR observations of NGC 300 ULX1, performing phaseaveraged and phase-resolved spectroscopy. Using the Bayesian framework we compared two physically motivated models for the source spectrum: Non-thermal accretion column emission modeled by a power law with a high-energy exponential roll-off (AC model) vs multicolor thermal emission from an optically thick accretion envelope plus a hard power-law tail (MCAE model). The AC model is an often used phenomenological model for the emission of X-ray pulsars, while the MCAE model has been recently proposed for the emission of the optically thick accretion envelope expected to form in ultraluminous (L X > 10 39 erg/s), highly magnetized accreting neutron stars. We combine the findings of our Bayesian analysis with qualitative physical considerations to evaluate the suitability of each model. Results. The low-energy part (<2 keV) of the source spectrum is dominated by non-pulsating, multicolor thermal emission. The (pulsating) high energy continuum is more ambiguous. If modelled with the AC model a residual structure is detected, that can be modeled using a broad Gaussian absorption line centered at ∼12 keV. However, the same residuals can be successfully modeled using the MCAE model, without the need for the absorption-like feature. Model comparison, using the Bayesian approach strongly indicates that the MCAE model -without the absorption line -is the preferred model. Conclusions. The spectro-temporal characteristics of NGC 300 ULX1 are consistent with previously reported traits for X-ray pulsars and (pulsating) ULXs. All models considered strongly indicate the presence of an accretion disk truncated at a large distance from the central object, as has been recently suggested for a large fraction of both pulsating and nonpulsating ULXs. The hard, pulsed emission is not described by a smooth spectral continuum. If modelled by a broad Gaussian absorption line, the fit residuals can be interpreted as a cyclotron scattering feature (CRSF) compatible with a ∼10 12 G magnetic field. However, the MCAE model can successfully describe the spectral and temporal characteristics of the source emission, without the need for an additional absorption feature and yields physically meaningful parameter values. Therefore strong doubts are cast on the presence of a CRSF in NGC 300 ULX1.

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Section: Accretion Column Modelsupporting

confidence: 50%

Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1

Koliopanos

Vasilopoulos

Buchner

et al. 2019

A&A

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“…Attempts to fit the same model as Carpano et al (2018) to the continuum did not result in an acceptable fit, with a χ 2 r =1.17 for 515 dof (χ 2 =604.7), unphysical and unconstrained parameters and clear structure in the residuals, particularly for the 2001 and 2003 spectra. Untying the parameters, does little to improve the fit nor does deleting components to emulate the models of Fornasini et al (2017). The TBabs*pcfabs(po*highecut) model has an identical χ 2 r =1.17 for 515 dof (χ 2 =604.7), whereas the TBabs*(bbody+po*highecut) had χ 2 r values of 1.39 (χ 2 =724.64) for 521 dof and 1.37 for 517 dof (χ 2 =709.19) for when the blackbody temperature components are tied across all observations or allowed to vary respectively.…”

Section: The X-ray Continuummentioning

confidence: 99%

CI Camelopardalis: The first sgB[e]-high mass X-ray binary twenty years on: A supernova imposter in our own Galaxy?

Bartlett

Clark

Negueruela

2019

A&A

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Context. The Galactic supergiant B[e] star CI Camelopardalis (CI Cam) was the first sgB[e] star detected during an X-ray outburst. The star brightened to ∼2 Crab in the X-ray regime (∼ 5 × 10 −8 ergs cm −2 s −1 in the 2-25 keV range) within hours before decaying to a quiescent level in less than 2 weeks, clearly indicative of binarity. Since the outburst of CI Cam, a number of sgB[e] stars have been identified as X-ray overluminous for a single star (i.e., L X > 10 −7 L bol ). This small population has recently expanded to include two Ultra Luminous X-ray sources (ULX), Holmberg II X-1 and NGC300 ULX-1/supernova imposter SN2010da. Aims. Since the discovery of X-ray emission from CI Cam, there have been many developments in the field of massive binary evolution. In light of the recent inclusion of two ULXs in the population of X-ray bright sgB[e] stars, we revisit CI Cam to investigate its behaviour over several timescales and shed further light on the nature of the compact object in the system, its X-ray outburst in 1998 and the binary system parameters. Methods. We analyse archival XMM-Newton EPIC-pn spectra and light curves along with new data from Swift and NuSTAR. We also present high-resolution (R∼85,000) MERCATOR/HERMES optical spectra, including a spectrum taken 1.02 days after our NuSTAR observation. Results. Despite being in quiescence, CI Cam is highly X-ray variable on timescales of days, both in terms of total integrated flux and spectral shape. We interpret these variations by invoking the presence of an accreting compact companion immersed in a dense, highly structured, aspherical circumstellar envelope. The differences in the accretion flux and circumstellar extinction represent either changes in this environment, triggered by variable mass loss from the star, or the local conditions to the accretor due to its orbital motion. We find no evidence for pulsations in the X-ray light curve. Conclusions. CI Cam has many similarities with SN2010da across mid-IR, optical and X-ray wavelengths suggesting that, subject to distance determination for CI Cam, if CI Cam was located in an external galaxy its 1998 outburst would have led to a classification as a supernova imposter.

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“…There are no indications of spectral features in the fit residuals, including around the Fe Kα line complex at 6-7 keV. Moreover, considering the NuSTAR spectra alone, we find no evidence of a high-energy cutoff usually present in the hard X-ray spectra of HMXBs harboring accreting neutron stars (see, e.g., Coburn et al 2002;Krivonos et al 2015;Fornasini et al 2017). The photon index as inferred from the NuSTAR spectra is larger than Γ = 1.51±0.01 found at lower X-ray energies with Suzaku (Takahashi et al 2009).…”

Section: Phase-integrated Spectroscopymentioning

confidence: 55%

NuSTAR observation of LS 5039

Volkov,

Kargaltsev,

Younes

et al. 2021

Preprint

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LS 5039 is a high-mass γ-ray binary hosting a compact object of unknown type. NuSTAR observed LS 5039 during its entire 3.9 day binary period. We performed a periodic signal search up to 1000 Hz which did not produce credible period candidates. We do see the 9.05 s period candidate, originally reported by Yoneda et al. (2020) using the same data, in the Fourier power spectrum, but we find that the statistical significance of this feature is too low to claim it as a real detection. We also did not find significant bursts or quasi-periodic variability. The modulation with the orbital period is clearly seen and remains unchanged over a decade long timescale when compared to the earlier Suzaku light curve. The joint analysis of the NuSTAR and Suzaku XIS data shows that the 0.7-70 keV spectrum can be satisfactory described by a single absorbed power-law model with no evidence of cutoff at higher energies. The slope of the spectrum anti-correlates with the flux during the binary orbit. Therefore, if LS 5039 hosts a young neutron star, its X-ray pulsations appear to be outshined by the intrabinary shock emission. The lack of spectral lines and/or an exponential cutoff at higher energies suggests that the putative neutron star is not actively accreting. Although a black hole scenario still remains a possibility, the lack of variability or Fe Kα lines, which typically accompany accretion, makes it less likely.

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An XMM-Newton and NuSTAR Study of IGR J18214-1318: A Non-pulsating High-mass X-Ray Binary with a Neutron Star

Cited by 17 publications

References 109 publications

Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1

Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1

CI Camelopardalis: The first sgB[e]-high mass X-ray binary twenty years on: A supernova imposter in our own Galaxy?

NuSTAR observation of LS 5039

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