Multi-Wavelength study of magnetic cataclysmic variables

Abstract

Magnetic Cataclysmic Variables (MCVs) are binaries in which a primary magnetized white dwarf (WD) accretes material from Roche lobe-filling red dwarf companion. Two major classes of magnetic CVs are Polars and Intermediate Polars (IPs). Due to their interacting nature, magnetic CVs emit radiations over all wavelengths of the electromagnetic spectrum. This thesis provides a detailed multi-wavelength study of MCVs in order to understand the accretion flow geometry at their different evolutionary states. In order to better understand the evolutionary state and accretion flow of MCVs, one needs to increase the sample. Therefore, a sample of candidate MCVs was also taken to classify them into their proper classes. In order to accomplish the aim, we have used several ground-based observatories for observations in optical wavelength including 1-m class telescopes of ARIES and 2.01-m Himalayan Chandra telescope of IIA, and three spacebased observatories (XMM-Newton, Suzaku, and ROSAT) for observations in X-ray and UV band. A detailed optical (photometry, spectroscopy, and polarimetry) and X-ray timing and spectral analyses were performed for nine magnetic CVs. These are V2400 Oph, IPHAS J013032+622132, IPHAS J025828+635235, IPHAS J051814.33+294113.0, Paloma, CD Ind, RX J0859.1+0537, RX J0749.1-0549, and RX J0649.8-0737. First five systems are known and/or classified as IPs due to their large asynchronism nature, their stable optical and/or X-ray short period modulations, the presence of side-band frequencies in their power spectrum, and their hard X-ray spectrum which shows evidence of complex absorption along with the presence of strong Fe Kα emission lines. However, last four systems are called and/or identified as polars due to their synchronism or close to synchronism nature, the presence of high ionization and strong Balmer emission lines in their optical spectra, and due to the high magnetic field strength of WD.