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Zamanov, A. D.

doi:10.1023/a:1014056806811

Cited by 7 publications

(2 citation statements)

References 2 publications

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“…Previously the superorbital modulation is often discussed as the result of a cyclical change in the density/size of the circumstellar disk of the masssive companion (e.g., Ackermann et al 2013;Saha et al 2016), as such changes have been relatively well observed in Be star systems (e.g., Rivinius et al 2013), including Be/X-ray binaries (e.g., . For the Be disk in LS I +61°303, changes in the radius of the disk at the superorbital period has been clearly seen in long-term optical spectroscopy (Zamanov & Martí 2000;Zamanov et al 2013). However in order to explain the clear trend of the phase shifts we have obtained (cf., Figure 4), a non-axisymmetric structure is needed (axisymmetric changes cannot produce the phase shifts, which are a function of orbital phase).…”

Section: Discussionmentioning

confidence: 77%

Superorbital Modulation at GeV Energies in the γ-Ray Binary LS I + 61°303

Xing

Wang

Takata

2017

ApJ

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We report the results from our analysis of 8 years of the data for the γ-ray binary LS I +61°303, obtained with the Large Area Telescope onboard the Fermi Gamma-Ray Space Telescope. We find a significant dip around the binary's periastron in the superorbital light curves, and by fitting the light curves with a sinusoidal function, clear phase shifts are obtained. The superorbital modulation seen in the binary has been long known and different scenarios have been proposed. Based on our results, we suggest that the circumstellar disk around the Be companion of this binary may have a non-axisymmetric structure, which rotates at the superorbital period of 1667 days. As a result, the density of the ambient material around the compact star of the binary changes along the binary orbit over the superorbital period, causing the phase shifts in the modulation, and around periastron, the compact star probably enters the Be disk or switches the mode of its emission due to the intereaction with the disk, causing the appearance of the dip. We discuss the implications of this possible scenario to the observed superorbital properties at multiple frequencies.

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Section: Discussionmentioning

confidence: 77%

Superorbital Modulation at GeV Energies in the γ-Ray Binary LS I + 61°303

Xing

Wang

Takata

2017

ApJ

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“…Shorter timescale variability has also been detected in X-rays (Smith et al 2009;Torres et al 2012) and hinted at in the TeV range (Aliu et al 2013). Additionally, the source exhibits a periodic superorbital modulation with a period of P sup ≈ 4.5 years in Hα emission (Zamanov & Martí 2000) and in radio (Gregory 2002), X-ray (Li et al 2012), and GeV (Ackermann et al 2013) bands. This modulation could be attributed to precessing relativistic jets if the compact object is a black hole or to cyclic variations of the B0 Ve star envelope if the compact object is a neutron star.…”

Section: Introductionmentioning

confidence: 81%

Exceptionally Bright Tev Flares From the Binary Ls I +61° 303

Archambault

Archer

Aune

et al. 2016

ApJL

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The TeV binary system LS I +61 • 303 is known for its regular, non-thermal emission pattern which traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5 % and 15 % of the steady flux from the Crab Nebula (> 300 GeV). In this article, VERITAS observations of LS I +61 • 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. This is the brightest such activity from this source ever seen in the TeV regime. The strong outbursts have rise and fall times of less than a day. The short timescale of the flares, in conjunction with the observation of 10 TeV photons from LS I +61 • 303 during the flares, provides constraints on the properties of the accelerator in the source.

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Natural vibrations of a strip made of a composite material with a locally curved structure

Zamanov

2005

Mech Compos Mater

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Cited by 7 publications

References 2 publications

Superorbital Modulation at GeV Energies in the γ-Ray Binary LS I + 61°303

Superorbital Modulation at GeV Energies in the γ-Ray Binary LS I + 61°303

Exceptionally Bright Tev Flares From the Binary Ls I +61° 303

Natural vibrations of a strip made of a composite material with a locally curved structure

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