Observing the Evolution of the Universe

How did the universe evolve? The fine angular scale (l>1000) temperature and polarization anisotropies in the CMB are a Rosetta stone for understanding the evolution of the universe. Through detailed measurements one may address everything from the physics of the birth of the universe to the history of star formation and the process by which galaxies formed. One may in addition track the evolution of the dark energy and discover the net neutrino mass. We are at the dawn of a new era in which hundreds of square degrees of sky can be mapped with arcminute resolution and sensitivities measured in microKelvin. Acquiring these data requires the use of special purpose telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and the South Pole Telescope (SPT). These new telescopes are outfitted with a new generation of custom mm-wave kilo-pixel arrays. Additional instruments are in the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey. Full list of 177 author available at http://cmbpol.uchicago.ed

Continuum emission from active galactic nuclei

The processes taking place in active galactic nuclei that give rise to continuum emissions are discussed. Consideration is given to the sources in which thermal processes dominate and those which are dominated by nonthermal processes, as well as to the methods in which source properties can be deduced from millimeter and submillimeter observations. Attention is also given to sources where both thermal and nonthermal processes have to be considered, namely Seyfert-type galaxies (such as NGC 1068 and Arp 220) and radio-quiet QSOs. Possible future directions for millimeter and submillimeter observations of AGN are suggested

Round table discussion: UK future plans

The UK particle Physics and Astronomy Research Council (PPARC) is responsible for funding UK research on Early Universe physics and CMB research. In order to coordinate its portfolio of research facilities, exploitation activity, theory development and future technology R&D PPARC has appointed a ‘Science Commitee’ as its highest-level peer review body to advise the council on both current funding and future development requirements to ensure that UK remains at the forefront of these two closely-related areas of science. The Science Comittee is advised by 4 panels in the areas of Astrophysics, Particle Physics, Solar System and Particle Astrophysics, with the last of these covering CMB science. With the advice of these panels a ‘Roadmap’ is laid out which highlights the top-level priorities for PPARC Science and then goes into detail regarding currently funded and potential future projects

Millimetre observations of X-Ray Bl-Lacertae

I present the first 1.3-mm observations of a complete sample of 10 X-ray- selected BL Lacertae objects (XBLs), together with complementary measurements of a complete sample of nine radio-selected BL Lacs (RBLs). Three XBLs have firm detections and one has a marginally significant detection. None of the XBLs has a radio spectrum rising steeply into the millimetre region, and the radio-millimetre spectral indices of the XBLs detected are within the range found for the RBLs. However, the overall millimetre-X-ray spectra of the XBLs are much flatter than for any RBL

Are there two populations of Bl-Lacertae objects

We present single-epoch infrared photometry of two complete samples of BL Lacertae objects, one radio-selected (RBLs) and one X-ray-selected (XBLs). we find that the RBLs fall into two distinct groups on the (J - H)-( H - K) plane, corresponding to those sources in which the host galaxy makes a significant contribution to the infrared colours and those with higher redshift whose infrared spectra are dominated by power-law non-thermal emission. We also find that the XBLs have colours intermediate between these two groups (although with significant scatter). We show that the infrared colours of Fanaroff-Riley class 1 galaxies (FR1), XBLs and RBLs are consistent with mixing of stellar emission with an increasing proportion of non-thermal emission, and argue that the FR1s, XBLs and RBLs form part of a single population, with the FR1s and XBLs both being at larger angles to the line of sight than are the RBLs, and differing only in the luminosities of their non-thermal components

Are BL Lac objects too large to be gravitationally lensed?

BL LACERTAEobjects are extragalactic sources, generally of low redshift, with highly variable, strongly polarized continuum emission ranging from radio wavelengths to X-rays, but with little or no evidence of line emission. It has been suggested1that BL Lacs are in fact more distant radio-loud, optically violently variable (OVV) quasars whose continuum is enhanced, relative to the line emission, by gravitational lensing caused by a star in an intervening galaxy. I argue here, however, that the spectral similarity of BL Lacs and OWs over a wide wavelength range can be explained by gravitational lensing only if the continuum-emitting region is small, a requirement that is contradicted by independent observations

Models for high-frequency radio outbursts in extragalactic sources, with application to the early 1983 millimeter-to-infrared flare of 3C 273

The present models for compact radio source variability, with reference to the early 1983 mm-to-IR flare of the quasar 3C 273, indicate that the outburst spectrum's early evolution is most easily explained if the flaring component is expanding. The models encompass the effects of synchrotron, Compton, and expansion losses, as well as variable injection of relativistic electrons and magnetic field. A model based on a uniform expanding source requires comparatively artificial variations of particle injection with source radius, in order to explain the 3C 273 flare data; superior results are noted for a second model in which the outburst is due to a shock wave passing through an adiabatic, conical, relativistic jet

SCUBA: the submillimeter common-user bolometer array for the James Clerk Maxwell Telescope

A submillimeter continuum array instrument being built for the 15-m James Clerk Maxwell Telescope on Mauna Kea, Hawaii is described. The instrument contains 2 arrays, one of 91 pixels optimized for 438 microns and the second of 37 pixels optimized for 855 microns. Both are hexagonally close-packed, with each pixel having diffraction-limited angular resolution. Conical horns and single-moded waveguides are used to couple to the submillimeter beams, minimizing the bolometer background loading. A filter changing mechanism allows operations of the arrays at 350 and 750 microns. Single 'photometric' pixels are provided optimized for operation at 350, 600, 750, 1100, 1400 and 2000 microns. The instrument will have bolometers sensitive enough to reach the photon-noise sensitivity limit at both wavelengths, corresponding to an optical noise equivalent power (NEP) of 1.6 x 10 to the -16th WHz exp -1/2. This is achieved by cooling to 0.1 K, using a dilution refrigerator

The thermal component of the Seyfert galaxy NGC1275

The authors have been observing a range of galaxy type over the IR through millimetre region to determine the contribution of thermal emission from heated dust. It is now clear that the 'Starburst' phenomenon is widespread and has a range of luminosity. By studying the continuum spectrum of the radio-loud Seyfert galaxy NGC 1275 over many years, the authors have shown that it possesses a thermal component of luminosity comparable to the synchrotron luminosity. They interpret this thermal component as emission from dust heated by stars forming from material in an X-ray cooling accretion flow

The final frontier. Introduction.

"Focus: The final frontier". The authors introduce why the sub-mm view of the Universe is so important and explain why astronomy at this wavelength has not developed quite as fast as some other areas