Management of intracranial arterial dissection

Rajpal, Girish; Naik, Vikas

doi:10.4103/0028-3886.222834

Cited by 3 publications

(9 citation statements)

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“…They found significantly higher energy of the fluorescent Fe K α emission line (∼6.6 keV), which could be a blend of 6.4 keV emission line with 6.7 keV emission line originating from hot matter surrounding the neutron star. Naik & Paul (2012) with the same XMM-Newton observation which we have analysed here, found significant variability in the line parameters of the three Fe K α emission lines during eclipse and out-of-eclipse phases. They also suggest that the colder material, causing 6.4 keV line emission, is relatively close to the neutron star at most on the scale of the companion, while the hot matter producing the Fe XXV and Fe XXVI emission lines are further away as suggested by Ebisawa et al (1996).…”

Section: Introductionsupporting

confidence: 73%

“…Eclipse spectra of individual sources have been reported before (Cen X-3 - Naik & Paul 2012;Wojdowski, Liedahl & Sako 2001;Ebisawa et al 1996, 4U 1538−522 -Rodes-Roca et al 2011, 4U 1700−377 -van der Meer et al 2005a, Vela X-1 - Sako et al 1999;Schulz et al 2002). The scattered reports on individual sources do not give an overall picture of the extent of reprocessing during eclipse in HMXBs, i.e, what is the fractional luminosity compared to the out-of-eclipse spectrum, how do the shape of the continuum during the eclipse compare with the out-of-eclipse spectrum, relative strength of the Iron (Fe) fluorescence line and other Fe lines if present.…”

Section: Introductionmentioning

confidence: 63%

“…The fluxes of the Fe XXV and Fe XXVI emission lines increase by a factor of more than 5 but their equivalent widths fall by a factor of ∼2 in the out-of-eclipse phase compared to their values in the eclipse phase. An increase of equivalent width of fluorescent Fe K α emission lines has been observed in the out-of-eclipse phase compared to the eclipse phase earlier from the same XMM-Newton observation (Naik & Paul 2012) and from an ASCA observation of Cen X-3 (Ebisawa et al 1996).…”

Section: Of the Hmxbsmentioning

confidence: 74%

“…The equivalent width of the Fe emission lines in this source during eclipse is smaller than for other SgHMXBs with similar line of sight equivalent Hydrogen column density (N H ). Ebisawa et al (1996) and Naik & Paul (2012) have also found lower equivalent width of Fe emission lines in eclipse compared to out-of-eclipse with ASCA and XMM-Newton respectively. The wind in Cen X-3 is smooth (Wojdowski, Liedahl & Sako 2001).…”

Section: Cen X-3mentioning

confidence: 92%

“…The broad band (0.5-70 keV) eclipse and out-of-eclipse spectra of Cen X-3 with Suzaku (Naik, Paul & Ali 2011) were well fitted with partial covering powerlaw model with high-energy cutoff and Gaussian functions for the three Fe emission lines (6.4 keV, 6.7 keV, and 6.97 keV). Naik & Paul (2012) have obtained best fit with XMM-Newton eclipse and out-of-eclipse spectra in the energy range of (4-10 keV) with powerlaw and three Gaussian functions for the above three Fe emission lines. Powerlaw photon index were found to be the lowest in the eclipse phase which then increases with the increase of flux.…”

Section: Of the Hmxbsmentioning

confidence: 99%

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X-Ray Reprocessing: Through the Eclipse Spectra of High-mass X-Ray Binaries with XMM-Newton

Aftab¹,

Paul²,

Kretschmar³

2019

ApJS

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The study of X-ray reprocessing is one of the key diagnostic tools to probe the environment in X-ray binary systems. One difficult aspect of studying X-ray reprocessing is the presence of much brighter primary radiation from the compact star together with the reprocessed radiation. In contrast for eclipsing systems, the X-rays we receive during eclipse are only those produced by reprocessing of the emission from the compact star by the surrounding medium. We report results from a spectral study of the X-ray emission during eclipse and outside eclipse (when available) in 9 high mass X-ray binaries (HMXBs) with XMM-Newton EPIC pn to investigate different aspects of the stellar wind in these HMXBs. During eclipse the continuum component of the spectrum is reduced by a factor of ∼8-237, but the count-rate for 6.4 keV Iron emission line or complex of Iron emission lines in HMXBs are reduced by a smaller factor leading to large equivalent widths of the Iron emission lines. This indicates a large size for the line emission region, comparable to or larger than the companion star in these HMXB systems. However there are significant system to system differences. 4U 1538−52, in spite of having a large absorption column density, shows a soft emission component with comparable flux during the eclipse and out-of-eclipse phases. Emission from Hydrogen-like Iron has been observed in LMC X-4 for the first time, in the out-of-eclipse phase in one of the observations. Overall, we find significant differences in the eclipse spectrum of different HMXBs and also in their eclipse spectra against out-of-eclipse spectra.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 63%

Section: Of the Hmxbsmentioning

confidence: 74%

Section: Cen X-3mentioning

confidence: 92%

Section: Of the Hmxbsmentioning

confidence: 99%

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X-Ray Reprocessing: Through the Eclipse Spectra of High-mass X-Ray Binaries with XMM-Newton

Aftab¹,

Paul²,

Kretschmar³

2019

ApJS

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Fitting strategies of accretion column models and application to the broadband spectrum of Cen X-3

Thalhammer

Bissinger

Ballhausen

et al. 2021

A&A

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Due to the complexity of modeling the radiative transfer inside the accretion columns of neutron star binaries, their X-ray spectra are still commonly described with phenomenological models, for example, a cutoff power law. While the behavior of these models is well understood and they allow for a comparison of different sources and studying source behavior, the extent to which the underlying physics can be derived from the model parameters is very limited. During recent years, several physically motivated spectral models have been developed to overcome these limitations. Their application, however, is generally computationally much more expensive and they require a high number of parameters which are difficult to constrain. Previous works have presented an analytical solution to the radiative transfer equation inside the accretion column assuming a velocity profile that is linear in the optical depth. An implementation of this solution that is both fast and accurate enough to be fitted to observed spectra is available as a model in XSPEC. The main difficulty of this implementation is that some solutions violate energy conservation and therefore have to be rejected by the user. We propose a novel fitting strategy that ensures energy conservation during the χ2-minimization which simplifies the application of the model considerably. We demonstrate this approach as well as a study of possible parameter degeneracies with a comprehensive Markov-chain Monte Carlo analysis of the complete parameter space for a combined NuSTAR and Swift/XRT dataset of Cen X-3. The derived accretion-flow structure features a small column radius of ∼63 m and a spectrum dominated by bulk-Comptonization of bremsstrahlung seed photons, in agreement with previous studies.

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Ischemic stroke caused by spontaneous anterior circulation intracranial arterial dissections: patient series

Furst

Ellens

Bender

et al. 2023

Journal of Neurosurgery: Case Lessons

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BACKGROUND Intracranial arterial dissections (IADs) are classically associated with the vertebrobasilar system, yet are a devastating cause of ischemic stroke within the anterior circulation. Current literature regarding the surgical management of anterior circulation IAD is lacking. As a result, data on 9 patients presenting with ischemic stroke due to spontaneous anterior circulation IAD between 2019 and 2021 were collected in a retrospective manner. Symptoms, diagnostic modalities, treatment, and outcomes are presented for each case. Patients who underwent endovascular procedures had 10-minute follow-up angiography performed to identify signs of reocclusion, which prompted initiation of glycoprotein IIb/IIIa therapy and stent placement. OBSERVATIONS Seven patients underwent emergent endovascular intervention (stenting: n = 5; thrombectomy alone: n = 2). The remaining 2 were managed medically. Two patients developed progressive flow limiting stenosis requiring further intervention, 2 developed asymptomatic progressive stenosis/occlusion with robust collateral formation and the remainder have patent vasculature upon follow up imaging at 6 to 12 months. Seven patients had a modified Rankin Scale score of 1 or less at the 3-month follow-up. LESSONS IAD is a devastating yet rare cause of anterior circulation ischemic stroke. The treatment algorithm proposed resulted in positive clinical and angiographic outcomes warranting future consideration and study in the emergent management of spontaneous anterior circulation IAD.

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Management of intracranial arterial dissection

Cited by 3 publications

References 0 publications

X-Ray Reprocessing: Through the Eclipse Spectra of High-mass X-Ray Binaries with XMM-Newton

X-Ray Reprocessing: Through the Eclipse Spectra of High-mass X-Ray Binaries with XMM-Newton

Fitting strategies of accretion column models and application to the broadband spectrum of Cen X-3

Ischemic stroke caused by spontaneous anterior circulation intracranial arterial dissections: patient series

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