Simultaneous modelling of X-rays emission and optical polarization of intermediate polars using the CYCLOPS code: the case of V405 Aurigae

ISABEL J. LIMA; G. J. M. LUNA; CLAUDIA V. RODRIGUES; KARLEYNE SILVA

Congreso; AAS Meeting #233; 2018

Intermediate polars (IPs) are asynchronous magnetic cataclysmic variables, binary systems in which mass transfer occurs from a low-mass star onto a magnetic white dwarf (WD). Magnetic accretion forms a shock near the WD, and the compressed material?the post-shock region?is responsible by the system emission in high energies. Some IPs present optical polarization that comes from cyclotron emission also by the post-shock region. Our main goal is to model simultaneously optical and X-ray data using the CYCLOPS code in order to study the magnetic accretion structure and geometry of IPs. CYCLOPS was developed by our group to perform multi-wavelength fitting of the accretion column flux. It considers cyclotron and free-free emission from a 3D post-shock region, which is non-homogeneous in terms of density and temperature. V405 Aurigae is considered the highest magnetic field IP. Previous studies of this system were not successful in proposing a geometry that explains both the optical and X-ray data. In this study, we present a model that reproduces the V405 Aurigae observations: broadband (UBVRI) circular polarization and photometry, as well as the X-ray spectrum and light curve. We compare scenarios using one or two post-shock regions. In particular, we propose an one-region model that is able to explain the observed data. Our results also suggest high magnetic field (B = 3.6 x 107 ± 0.5 MG) makes V405 Aurigae a possible progenitor of a polar.