XMM-Newton observations of the dwarf nova YZ Cnc in quiescence
Abstract
We present results from the XMM-Newton observations of the dwarf nova YZ Cnc in a quiescent state. We have performed a detailed time series analysis of the resulting light curves. Unusually, we do not detect any orbital modulation in the UV, with only marginal evidence for X-ray modulation on this period. Although there are peaks in the X-ray periodograms at periods less than 5000 s, we attribute them to red noise effects and assign significance to them using a novel approach. The variability in the UV and optical bands can also be modelled as a result of aperiodic variability (red noise) in the system. There is evidence that the UV and X-ray fluxes are anti-correlated with a time delay of about 100 s, with the UV lagging behind the X-ray emission. This anti-correlation is intriguing, but is only present on two occasions lasting several 1000 s each. The X-ray spectrum shows similar emission features to other dwarf novae and is well fitted using a multi-temperature emission model. We measure a relatively high X-ray luminosity of ∼1.4× 1032 ergs/s, although this is consistent with a low binary inclination. Finally, we find evidence for a possible -1200 km s-1 blue shift in the fitted Fe K line energies, possibly indicating the presence of an outflow in this low inclination system.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2004
- DOI:
- 10.1051/0004-6361:20035843
- arXiv:
- arXiv:astro-ph/0403178
- Bibcode:
- 2004A&A...420..273H
- Keywords:
-
- accretion;
- accretion disks;
- stars: individual: YZ Cnc;
- stars: binaries: close;
- X-rays: stars;
- methods: data analysis;
- Astrophysics
- E-Print:
- 9 pages, accepted for publication in A&