The SCUBA HAlf degree extragalactic survey - III. Identification of radio and mid-infrared counterparts to submillimetre galaxies

Determining an accurate position for a submillimetre (submm) galaxy (SMG) is the crucial step that enables us to move from the basic properties of an SMG sample - source counts and 2D clustering - to an assessment of their detailed, multiwavelength properties, their contribution to the history of cosmic star formation and their links with present-day galaxy populations. In this paper, we identify robust radio and/or infrared (IR) counterparts, and hence accurate positions, for over two-thirds of the SCUBA HAlf-Degree Extragalactic Survey (SHADES) Source Catalogue, presenting optical, 24-μm and radio images of each SMG. Observed trends in identification rate have given no strong rationale for pruning the sample. Uncertainties in submm position are found to be consistent with theoretical expectations, with no evidence for significant additional sources of error. Employing the submm/radio redshift indicator, via a parametrization appropriate for radio-identified SMGs with spectroscopic redshifts, yields a median redshift of 2.8 for the radio-identified subset of SHADES, somewhat higher than the median spectroscopic redshift. We present a diagnostic colour-colour plot, exploiting Spitzer photometry, in which we identify regions commensurate with SMGs at very high redshift. Finally, we find that significantly more SMGs have multiple robust counterparts than would be expected by chance, indicative of physical associations. These multiple systems are most common amongst the brightest SMGs and are typically separated by 2-6 arcsec, similar to 15-20/sin i kpc at z~ 2, consistent with early bursts seen in merger simulations.

La sabiduría árabe antigua reflejada en los proverbios de Al-Maydani: traducción y análisis paremiológico de un corpus seleccionado

Little is known about Ancient Arabia before the arrival of Islam as it was an area with few inhabited settlements and it was mostly a passageway for traders. In those inhabited settlements we could find some settled Arabs, but the prevailing life style was that of the rest of the population, nomadic Bedouin Arabs who travelled from place to place looking for water and pasture for their cattle, which they lived off. The desert was their natural habitat, a hostile environment full of danger where life was not easy. Camel taming made it possible for them to live that nomadic lifestyle, and the Bedouins became inseparable from their camels and from their horses and cattle. In order to make a living they worked as hunters, transported caravans, and plundered too. In the pre-Islamic era, knowledge was transmitted by oral communication, so very little written information about that time and place remains. One thing that has been handed down are proverbs, which after the 8th Century started to be collected by several writers in various written works. Given the characteristics of those proverbs, which are conserved almost intact from their origins, we can learn much about the lifestyle in Ancient Arabia. What is to be investigated within this thesis is whether through Paremiology it is possible to learn more about this area at this historic moment that precedes the arrival of Islam, and the first years of this religion. To learn about history, we usually rely on historians and palaeontologists, but this work will demonstrate that through Paremiology it is possible to know other aspects of culture, their knowledge, the way of life, thinking, society, etc...