7,243 research outputs found
XMM-Newton Observations of Evolution of Cluster X-Ray Scaling Relations at z=0.4-0.7
We present a spatially-resolved analysis of the temperature and gas density
profiles of galaxy clusters at z=0.4-0.7 observed with XMM-Newton. These data
are used to derive the total cluster mass within the radius r_500 without
assuming isothermality, and also to measure the average temperature and total
X-ray luminosity excluding the cooling cores. We derive the high-redshift M-T
and L-T relations and compare them with the local measurements. The
high-redshift L-T relation has low scatter and evolves as L ~ (1+z)^{1.8\pm0.3}
for a fixed T, in good agreement with several previous Chandra and XMM-Newton
studies (Vikhlinin et al., Lumb et al., Maughan et al.). The observed evolution
of the M-T relation follows M_500 = A T^{3/2} E(z)^{-alpha}, where we measure
alpha=0.88\pm0.23. This is in good agreement with predictions of the
self-similar theory, alpha=1.Comment: ApJ in press, updated to match the accepted versio
Harmonic Twistor Formalism and Transgression on Hyperk\"ahler manifolds
In this paper we continue our study of the fourth order transgression on
hyper\"ahler manifolds introduced in the previous paper. We give a local
construction for the fourth-order transgression of the Chern character form of
an arbitrary vector bundle supplied with a self-dual connection on a four
dimensional hyperk\"ahler manifold. The construction is based on the harmonic
twistor formalism. Remarkably, the resulted expression for the fourth order
transgression is given in terms of the determinant of the
-operator defined on fibers of the twistor fibration.Comment: 10pp., Late
Some features of the fabrication of multilayer fiber composites by explosive welding
The fabrication of multilayer fiber composites by explosive welding is characterized by intense plastic deformation of the matrix material as it fills the spaces between fibers and by high velocity of the collision between matrix layers due to acceleration in the channels between fibers. The plastic deformation of the matrix layers and fiber-matrix friction provide mechanical and thermal activation of the contact surfaces, which contributes to the formation of a bond. An important feature of the process is that the fiber-matrix adhesion strength can be varied over a wide range by varying the parameters of impulsive loading
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