Accretion Flow in Magnetic Cataclysmic Variables

Wu, Kinwah; Cropper, Mark; Ramsay, Gavin; Saxton, C. J.; Bridge, Chris

doi:10.1088/1009-9271/3/s1/235

Cited by 12 publications

(12 citation statements)

References 34 publications

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“…This is fairly bright for an IP in the dim, hard state (although a distance of ∼2.5 kpc would be required in order for this to be the brightest; Stacey et al 2011). However, whilst the source is relatively bright, the hard continuum precludes a useful RGS analysis which could help identify soft emission/absorption features (and identify the physical, multitemperature nature of the emission; Wu et al 2003).…”

Section: X‐ray Spectral Analysismentioning

confidence: 99%

Identifying a new intermediate polar using XMM-Newton and INTEGRAL

Middleton¹,

Cackett²,

Shaw³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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The bright X-ray source 2XMMi J180438.7−145647 is fortunate to have long baseline observations in INTEGRAL that complement observations taken by other missions. Optical spectroscopy of this object has suggested a distance of ∼7 kpc and an identification with a low-mass X-ray binary. We instead use the X-ray data from 0.3 to 40 keV to identify the source as a bright intermediate polar (IP) with an estimate for the white dwarf mass of ∼0.60 M . This identification is supported by the presence of an iron triplet, the component lines of which are some of the strongest seen in IPs, and the signature of the spin period of the white dwarf at ∼24 min. We note that the lack of broad-band variability may suggest that this object is a stream-fed IP, similar in many respects to the well-studied IP, V2400 Oph. Phase binning has allowed us to create spectra corresponding to the peaks and troughs of the light curve from which we determine that the spectra appear harder in the troughs, consistent with the behaviour of other IPs binned on their spin periods. This work strongly suggests a misidentification in the optical due to the presence of large columns of enshrouding material. We instead propose a distance to the source of <2.5 kpc to be consistent with the luminosities of other IPs in the dim, hard state. The considerable flux of the source together with the strength of the iron lines may, in future, allow the source to be used to diagnose the properties of the shock-heated plasma and the reflected component of the emission.

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Section: X‐ray Spectral Analysismentioning

confidence: 99%

Identifying a new intermediate polar using XMM-Newton and INTEGRAL

Middleton¹,

Cackett²,

Shaw³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…For accretion on to white dwarfs in magnetic cataclysmic variables (mCVs) (Warner 1995; Cropper 1990), the magnetic field not only directs the flow but could also dictate the radiative‐loss processes (see e.g. Wu et al 2003). This, in turn, alters the flow hydrodynamics, leading to observable consequences, for example, in the optical/infrared polarization and keV X‐ray spectra of the system.…”

Section: Introductionmentioning

confidence: 99%

X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel

Saxton

Canalle

et al. 2007

Monthly Notices of the Royal Astronomical Society

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We investigate the hydrodynamics of accretion channelled by a dipolar magnetic field (funnel flows). We consider situations in which the electrons and ions in the flow cannot maintain thermal equilibrium [two-temperature (2T) effects] due to strong radiative loss, and determine the effects on the keV X-ray properties of the systems. We apply this model to investigate the accretion shocks of white dwarfs in magnetic cataclysmic variables (mCVs). We have found that the incorporation of 2T effects could harden the keV X-rays. Also, the dipolar model yields harder X-ray spectra than the standard planar model if white dwarf is sufficiently massive ( 1 M ). When fitting observed keV X-ray spectra of mCVs, the inclusion of 2T hydrodynamics and a dipolar accretion geometry lowers estimates for white dwarf masses when compared with masses inferred from models excluding these effects. We find mass reductions 9 per cent in the most massive cases.

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“…Being interacting red dwarf-white dwarf pairs, polars are a class of Cataclysmic variable (CV). For a review of cataclysmic variables and polars, see Cropper (1990), Warner (1995), Wu (2000), Beuermann (2002), Wu et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Spectral behavior of AM Her and QQ Vul in high and intermediate states in the UV

Sanad

2010

Astrophys Space Sci

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We present low resolution UV spectra of two polar systems, AM Her and QQ Vul from the observations taken by the IUE (International Ultraviolet Explorer) of the period between 1978-1996 and 1983-1996 for both systems respectively, to accomplish a large scale study of what happens to the ultraviolet flux of C IV 1550 Å spectral line during different orbital phases. Two spectra for both systems showing the variations in line fluxes and line widths at different orbital phases in high and intermediate states are presented. We concentrated on calculating the line fluxes and line widths of C IV 1550 Å emission line originating in the accretion stream. Our results show that there is spectral variability for the aformentioned physical parameters at different times, similar to that known for the light curve (Heise and Verbunt, Astron. Astrophys. 189:112, 1988; Gansicke et al., Astron. Astrophys. 303:127, 1995;Kafka and Honeycutt, Astron. J. 125:2188K, 2003). We attribute it to the variations of both density and temperature as a result of changing the mass transfer rate (Hutchings et al., Astron. J. 123:2841H, 2002 King and Lasota, Astron. Astrophys. 140L:16K, 1984) which is responsible for this spectral variability. Also we found that the line fluxes of AM Her are greater than the line fluxes of QQ Vul, while the line widths of both systems are approximately the same.

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Accretion Flow in Magnetic Cataclysmic Variables

Cited by 12 publications

References 34 publications

Identifying a new intermediate polar using XMM-Newton and INTEGRAL

Identifying a new intermediate polar using XMM-Newton and INTEGRAL

X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel

Spectral behavior of AM Her and QQ Vul in high and intermediate states in the UV

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