Pulsars, transients and relativistic astrophysics

Abstract:

We present a new, high resolution (5 '' per pixel) near-infrared extinction map of the Nuclear Bulge using data from the UKIDSS-GPS. Using photometry from the J, H and K-bands we show that the extinction law parameter a is also highly variable in this region on similar scales to the absolute extinction. We show that only when this extinction law variation is taken into account can the extinction be measured consistently at different wavelengths.

Abstract:

We examine the radio properties of EGRET-detected blazars observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). VIPS has a flux limit roughly an order of magnitude below the MOJAVE survey and most other samples that have been used to study the properties of EGRET blazars. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux density. We do find that the EGRET-detected blazars tend to have higher brightness temperatures, greater core fractions, and possibly larger than average jet opening angles. A weak correlation is also found with jet length and with polarization. All of the well-established trends can be explained by systematically larger Doppler factors in the gamma-ray-loud blazars, consistent with the measurements of higher apparent velocities found in monitoring programs carried out at radio frequencies above 10 GHz. © 2007. The American Astronomical Society. All rights reserved.

Abstract:

This book focuses on solutions to the energy problem, and not just the problem itself.