XMM-Newtonobservations of polars in low accretion states
| Autor: | Gavin Ramsay, Mark Cropper, Kinwah Wu, K. O. Mason, F. A. Córdova, W. Priedhorsky |
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| Rok vydání: | 2004 |
| Předmět: |
Physics
Flux distribution 010504 meteorology & atmospheric sciences Astrophysics::High Energy Astrophysical Phenomena Astrophysics (astro-ph) FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Light curve 01 natural sciences Accretion (astrophysics) Spectral line Space and Planetary Science 0103 physical sciences 010303 astronomy & astrophysics Order of magnitude 0105 earth and related environmental sciences |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 350:1373-1384 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1111/j.1365-2966.2004.07732.x |
| Popis: | We have made a series of snap-shot observations of 37 polars using XMM-Newton. We found that 16 of these systems were in a low, or much reduced, accretion state. Of those, 6 were not detected in X-rays. This suggests that in any survey of polars, around half will be in a low accretion state. We tested if there was a bias towards certain orbital periods: this is not the case. Of the 10 systems which were detected at low, but significant rates in X-rays, 8 showed significant variability in their X-ray light curves. This implies that non-uniform accretion still takes place during low accretion epochs. The bolometric luminosity of these systems is ~10^30 ergs s, two orders of magnitude less than for systems in a high accretion state. The X-ray spectra show no evidence of a distinct soft X-ray component. However, the X-ray and UV data imply that such a low temperature component exists: its temperature is low enough for its flux distribution to move outside the bandpass of the X-ray instruments. Comment: accepted MNRAS |
| Databáze: | OpenAIRE |
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