X-Ray Observations of VY Scl-Type Nova-Like Binaries in the High and Low State

• Main Authors: P. Zemko, M. Orio
• Format: Article
• Language: English
• Published: CTU Central Library 2015-02-01
• Series: Acta Polytechnica CTU Proceedings
• Online Access: https://ojs.cvut.cz/ojs/index.php/APP/article/view/2920

Four VY Scl-type nova-like systems were observed in X-rays both during the low and the high optical states. They are BZ Cam, MV Lyr, TT Ari, and V794 Aql. Using archival ROSAT, <em>Swift</em> and <em>SUZAKU</em> observations we found that the X-ray flux for BZ Cam is higher during the low state, but there is no supersoft X-ray source (SSS) that would indicate the thermonuclear burning predicted in a previous article. The X-ray flux is lower by a factor 2–10 in the low than the high state in other systems, and does not reflect the drop in <em>˙M</em> inferred from optical and UV data. The best fit model for the X-ray spectra is a collisionally ionized plasma model. The X-ray flux may originate in a shocked wind or in accretion onto polar caps in intermediate polar systems that continues even during the low state.