We present medium-resolution (lambda/Delta lambda similar to 20 000) ultraviolet spectra covering the 1155-1760 angstrom spectral range of the Seyfert 1 galaxy Mrk 509 obtained using the Cosmic Origins Spectrograph (COS) ...

We discuss the choice of gauge field basis in multiple-U(1) gauge theories. We find that there is a preferred basis, specified by the charge orthogonality condition, in which the U(1) gauge fields do not mix under one-loop ...

Context. We present here the results of a 180 ks Chandra-LETGS observation as part of a large multi-wavelength campaign on Mrk 509. Aims. We study the warm absorber in Mrk 509 and use the data from a simultaneous HST-COS ...

We present the results of a similar to 160 ks-long XMM-Newton observation of the Seyfert 1 galaxy Mrk 279. The spectrum shows evidence of both broad and narrow emission features. The FeK alpha line may be equally well ...

Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of the abundance by comparing local and higher redshift galaxies. However, the methods used so far have substantial ...

We perform a Monte Carlo simulation calculation of the critical coupling constant for the continuum two-dimensional (lambda/4) phi(4) theory. The critical coupling constant we obtain is [lambda/mu(2)](crit) = 10.26(-.04)(+.08). ...