POLAR project: a numerical study to optimize the target design

Busschaert, C.; Falize, É.; Loupias, B.; Michaut, C.; Ravasio, A.; Pełka, A.; Yurchak, Roman; Kœnig, M.

doi:10.1088/1367-2630/15/3/035020

Cited by 10 publications

(9 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Additionally, it should be emphasized that the PSAC presents interesting similarity properties that allow us to reproduce a scaled model in laboratory on measured scales (Falize et al 2011b;Busschaert et al 2013b). This is the main objective of a laboratory astrophysics project: the POLAR project (Falize et al 2011a).…”

Section: Discussionmentioning

confidence: 99%

Quasi-periodic oscillations in accreting magnetic white dwarfs

Busschaert

Falize

Michaut

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. The high magnetic field strength leads to the formation of an accretion column instead of an accretion disk. High-energy radiation coming from those objects is emitted from the column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. Aims. We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. Methods. The radiation hydrodynamics code H was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. Synthetic light curves and X-ray spectra were extracted from numerical simulations. A fast Fourier analysis was performed on the simulated light curves. The oscillation frequencies and amplitudes in the X-ray and optical domains are studied to compare those numerical results to observational ones. Different dimensional formulae were developed to complete the numerical evaluations. Results. The complete characterization of the emitting region is described for the two main radiative regimes: when only the bremsstrahlung losses and when both cyclotron and bremsstrahlung losses are considered. The effect of the non-linear cooling instability regime on the accretion column behaviour is analysed. Variation in luminosity on short timescales (∼1 s quasi-periodic oscillations) is an expected consequence of this specific dynamic. The importance of secondary shock instability on the quasi-periodic oscillation phenomenon is discussed. The stabilization effect of the cyclotron process is confirmed by our numerical simulations, as well as the power distribution in the various modes of oscillation.

show abstract

Section: Discussionmentioning

confidence: 99%

Quasi-periodic oscillations in accreting magnetic white dwarfs

Busschaert

Falize

Michaut

et al. 2015

A&A

View full text Add to dashboard Cite

show abstract

“…In this case, the structure of the accretion column and its dynamics can be diagnosed precisely under variable experimental conditions, thus allowing a potential detailed analysis of the quasi-periodic oscillation phenomena in laboratory. Conclusive preliminary results for the building of an accretion shock similar to what is observed in accreting magnetic white dwarfs have already been obtained in the context of the POLAR project, using the LULI 2000 laser facility Michaut et al 2012;Busschaert et al 2013). Future more promising prospects are expected from the more powerful NIF and LMJ lasers (Moses et al 2009;Lion 2010).…”

Section: Introductionmentioning

confidence: 89%

Quasi-periodic oscillations in accreting magnetic white dwarfs

Bonnet‐Bidaud

Mouchet

Busschaert

et al. 2015

A&A

View full text Add to dashboard Cite

Quasi-periodic oscillations (QPOs) are observed in the optical flux of some polars with typical periods of 1 to 3 s but none have been observed yet in X-rays where a significant part of the accreting energy is released. QPOs are expected and predicted from shock oscillations. Most of the polars have been observed by the XMM-Newton satellite. We made use of the homogeneous set of observations of the polars by XMM-Newton to search for the presence of QPOs in the (0.5-10 keV) energy range and to set significant upper limits for the brightest X-ray polars. We extracted high time-resolution X-ray light curves by taking advantage of the 0.07 s resolution of the EPIC-PN camera. Among the 65 polars observed with XMM-Newton from 1998 to 2012, a sample of 24 sources was selected on the basis of their counting rate in the PN instrument to secure significant limits. We searched for QPOs using Fast Fourier Transform (FFT) methods and defined limits of detection using statistical tools. Among the sample surveyed, none shows QPOs at a significant level. Upper limits to the fractional flux in QPOs range from 7% to 71%. These negative results are compared to the detailed theoretical predictions of numerical simulations based on a 2D hydrodynamical code presented in Paper II. Cooling instabilities in the accretion column are expected to produce shock quasi-oscillations with a maximum amplitude reaching ∼40% in the bremsstrahlung (0.5-10 keV) X-ray emission and ∼20% in the optical cyclotron emission. The absence of X-ray QPOs imposes an upper limit of ∼(5-10) g cm −2 s −1 on the specific accretion rate but this condition is found inconsistent with the value required to account for the amplitudes and frequencies of the observed optical QPOs. This contradiction outlines probable shortcomings with the shock instability model.

show abstract

“…The POLAR project [2,3] aims to replicate in the laboratory some of the hydrodynamic processes occurring in X-ray binary star systems known as magnetic cataclysmic variables [4,5] . In these binary stars, matter from a cold Correspondence to: C. Spindloe, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Chilton, Didcot, Oxon OX11 0QX, UK.…”

Section: Introductionmentioning

confidence: 99%

Target fabrication for the POLAR experiment on the Orion laser facility

Spindloe

Wyatt

Haddock

et al. 2015

High Pow Laser Sci Eng

View full text Add to dashboard Cite

(2013)), studied conditions relevant to the radiation-hydrodynamic processes occurring in a remarkable class of astrophysical star systems known as magnetic cataclysmic variables. A large number of complex fabrication technologies and research and development activities were required to field a total of 80 high-specification targets. Target design and fabrication procedures are described and initial alignment and characterization data are discussed.

show abstract

POLAR project: a numerical study to optimize the target design

Cited by 10 publications

References 26 publications

Quasi-periodic oscillations in accreting magnetic white dwarfs

Quasi-periodic oscillations in accreting magnetic white dwarfs

Quasi-periodic oscillations in accreting magnetic white dwarfs

Target fabrication for the POLAR experiment on the Orion laser facility

Contact Info

Product

Resources

About