XMM-Newton observations of the eclipsing polar V2301 Oph

Ramsay, Gavin; Cropper, Mark

doi:10.1111/j.1365-2966.2007.12011.x

Cited by 22 publications

(23 citation statements)

References 33 publications

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“…The white dwarf mass is not strictly determined, but an upper limit of M < 1.2 M is found from the eclipse modelling and it is suggested that an acceptable range is M = 1.0-1.1 M . (Ramsay & Cropper 2007). Using a distance of 150 pc, an unabsorbed bolometric X-ray luminosity of L x = 2 × 10 32 erg s −1 is derived from the spectral analysis of the bright phase during the XMM observations by Ramsay & Cropper (2007).…”

Section: V2301 Ophmentioning

confidence: 99%

Quasi-periodic oscillations in accreting magnetic white dwarfs

Bonnet‐Bidaud

Mouchet

Busschaert

et al. 2015

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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.

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Section: V2301 Ophmentioning

confidence: 99%

Quasi-periodic oscillations in accreting magnetic white dwarfs

Bonnet‐Bidaud

Mouchet

Busschaert

et al. 2015

A&A

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“…In the few systems lacking distinct soft X-ray emission, such as 2XMMp J131223.4+173659 (Vogel et al 2008) and V2301 Oph (Ramsay & Cropper 2007), the flux maximum of the reprocessed component appears to be shifted towards the EUV and UV regime. The same could apply to objects that show a detectable, but very weak soft component, such as EV UMa (Ramsay & Cropper 2003).…”

Section: Flux Ratios From Multi-temperature Spectral Modelingmentioning

confidence: 99%

X-ray spectroscopy and photometry of the long-period polar AI Trianguli with XMM-Newton

Traulsen

Reinsch

Schwarz

et al. 2010

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Context. The energy balance of cataclysmic variables with strong magnetic fields is a central subject in understanding accretion processes on magnetic white dwarfs. With XMM-Newton, we perform a spectroscopic and photometric study of soft X-ray selected polars during their high states of accretion. Aims. On the basis of X-ray and optical observations of the magnetic cataclysmic variable AI Tri, we derive the properties of the spectral components, their flux contributions, and the physical structure of the accretion region in soft polars.Methods. We use multi-temperature approaches in our xspec modeling of the X-ray spectra to describe the physical conditions and the structures of the post-shock accretion flow and the accretion spot on the white-dwarf surface. In addition, we investigate the accretion geometry of the system by completing a timing analysis of the photometric data. Results. Flaring soft X-ray emission from the heated surface of the white dwarf dominates the X-ray flux during roughly 70% of the binary cycle. This component deviates from a single black body and can be described by a superimposition of mildly absorbed black bodies with a Gaussian temperature distribution between kT bb,low := 2 eV and kT bb,high = 43.9 +3.3 −3.2 eV, and N H,ISM = 1.5 +0.8 −0.7 ×10 20 cm −2 . In addition, weaker hard X-ray emission is visible nearly all the time. The spectrum from the cooling post-shock accretion flow is most closely fitted by a combination of thermal plasma mekal models with temperature profiles adapted from prior stationary two-fluid hydrodynamic calculations. The resulting plasma temperatures lie between kT MEKAL,low = 0.8 +0.4 −0.2 keV and kT MEKAL,high = 20.0 +9.9 −6.1 keV; additional intrinsic, partial-covering absorption is on the order of N H,int = 3.3 +2.5 −1.2 × 10 23 cm −2 . The soft X-ray light curves show a dip during the bright phase, which can be interpreted as self-absorption in the accretion stream. Phase-resolved spectral modeling supports the picture of one-pole accretion and self-eclipse. One of the optical light curves corresponds to an irregular mode of accretion. During a short XMM-Newton observation at the same epoch, the X-ray emission of the system is clearly dominated by the soft component.

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“…In most AM Her stars, the soft component originates from the heated atmosphere of the white dwarf around the accretion spot. Thus, 2XMM1312 joins the group of now 9 out of ∼80 polars without a soft component (Ramsay & Cropper 2007). A likely explanation for the non-detection of the soft component is its low temperature which shifts the emission towards lower energies not covered by the X-ray cameras of the XMM-Newton.…”

Section: = 28 × 10mentioning

confidence: 99%

The serendipituous discovery of a short-period eclipsing polar in 2XMMp

Vogel¹,

Byckling

Schwope³

et al. 2008

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We report the serendipituous discovery of the new eclipsing polar 2XMMp J131223.4+173659. Its striking X-ray light curve attracted immediate interest when we were visually inspecting the source products of the 2XMMp catalogue. This light curve revealed its likely nature as a magnetic cataclysmic variable of AM Herculis (or polar) type with an orbital period of ∼92 min, which was confirmed by follow-up optical spectroscopy and photometry. 2XMMp J131223.4+173659 probably has a one-pole accretion geometry. It joins the group of now nine objects that show no evidence of a soft component in their X-ray spectra despite being in a high accretion state, thus escaping ROSAT/EUVE detection. We discuss the likely accretion scenario, the system parameters, and the spectral energy distribution.

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XMM-Newton observations of the eclipsing polar V2301 Oph

Cited by 22 publications

References 33 publications

Quasi-periodic oscillations in accreting magnetic white dwarfs

Quasi-periodic oscillations in accreting magnetic white dwarfs

X-ray spectroscopy and photometry of the long-period polar AI Trianguli with XMM-Newton

The serendipituous discovery of a short-period eclipsing polar in 2XMMp

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