Accretion Flows in Magnetic Cataclysmic Variables

Abstract

ESUMENPreseiitainos los rosnltados d(' sirnulacionos quo exploran la variedad de flujos de acrecion posibles en variables cal-aclisiiiicas iiiay,iieliras (mCVs). Niiestras simulaciories evoliicionan hasta alcanzar periodos de equilibrio qne abarcaii 0.01 < /3;pir,/Porb < 0.6, y los flujos resultantes varian desde sistemas alimentados por disco en Pspin/Porb ~ 0.01 -0.1 a sistciiias alinuaitados por corrientes en Pspin/Porb ~ 0.1 -0.5 y sistemas alimentados d('sd(' un anillo ('ii el borde <'xl,ei ioi-del lobnlo de Roche de la enana blanca, en Pspin/Porb ~ 0.6. ABSTRACT '•V(' present l lu' results of simulations that explore the variety of accretion flows possible in magnetic cataclysmic variabk's (mCVs). Our simulations evolv(' to equilibrium periods spanning 0.01 < Pspin/Porb < 0.6 and the resulting flows vary from disc-fed systems at, Pspin/Porb ~ 0.01 -0.1, to stream fed systems at Pgpin/Porb 0 .1 -0.5 and systenns led from a ring at tlu' outer edge of the white dwarf's Roche lobe at Pspin/Porb ~ 0.6.

Spectroscopic observations of the intermediate polar EX Hydrae in quiescence

“…Also, tomography and the phasing of the spin waves have suggested that feeding by the accretion curtains of the material from the ring (ring-fed accretion) takes place. These findings support the models of Belle et al (2002) and Norton et al (2004) for EX Hya and the simulations done by Norton et al (2004a) which have shown that for systems with the parameters of EX Hya, the accreting material forms a ring at the outer edge of the primary Roche lobe, from where accretion curtains funnel down to the white dwarf surface.…”

“…Recently, Norton et al (2004Norton et al ( , 2004a have shown that for systems with P spin /P orb ∼ 0.72, when the mass ratio is smaller at q = 0.2, the material forms a ring near the edge of the primary Roche lobe, from where accretion curtains funnel down to the white dwarf surface, in agreement with King & Wynn (1999) and Belle et al (2002). The material is fed from the ring (ring-fed accretion) and channeled along the magnetic field lines (when the angle between the white dwarf spin axis and magnetic dipole axis is small i.e < 30 • , which is true for EX Hya).…”

Very fast photometric and X-ray observations of the intermediate polar V2069 Cygni (RX J2123.7+4217)

“…The material attaches to the field lines and is channelled on to the WD’s magnetic poles, where it undergoes a strong shock. Thereafter, it settles on the surface and cools by the emission of X‐ray bremsstrahlung and optical/infrared cyclotron (Rosen, Mason & Cordova 1988; Norton et al 2004a). As proposed by Evans & Hellier (2004), most likely the prominent double‐peaked modulation in the soft X‐ray emission is due to the changing viewing geometry on to the accreting polar caps.…”