Are the INTEGRAL Intermediate Polars Different?

Norton, Andrew; Barlow, E.J.; Butters, Olly and Wynn, G.A. (2008). Are the INTEGRAL Intermediate Polars Different? In: A Population Explosion: The Nature & Evolution of X-ray Binaries in Diverse Environments, 28 Oct - 2 Nov 2007, St Pete Beach, Florida, USA.

URL: http://conference.astro.ufl.edu/XRAYBIN/Proceeding...

Abstract

One of the biggest surprises of the INTEGRAL mission was the detection of large
numbers of magnetic cataclysmic variables – in particular the intermediate polar (IP) subclass.
Not only have many previously known systems been detected, but many new ones have also been
found and subsequently classified from optical follow-up observations, increasing the sample of IPs
by ! 15%. We have recently been using a particle hydrodynamic code to investigate the accretion
flows of IPs and determine the equilibrium spin-rates and accretion flow patterns across a wide range
of orbital periods, mass ratios and magnetic field strengths. We use the results of these accretion
flow simulations to examine whether the INTEGRAL IPs differ from the overall population and
conclude that they do not. Most IPs are likely to be INTEGRAL sources, given sufficient exposure.
Currently however, none of the 'EX Hya-like' IPs, with large spin-to-orbital period ratios and short
orbital periods, are detected by INTEGRAL. If this continues to be the case once the whole sky
has a comparable INTEGRAL exposure, it may indicate that the ring-like mode of accretion which
we demonstrate occurs in these systems is responsible for their different appearance.

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