Luminosity function, sizes and FR dichotomy of radio-loud AGN

The radio luminosity function (RLF) of radio galaxies and radio-loud quasars is often modelled as a broken power-law. The break luminosity is close to the dividing line between the two Fanaroff-Riley (FR) morphological classes for the large-scale radio structure of these objects. We use an analytical model for the luminosity and size evolution of FRII-type objects together with a simple prescription for FRI-type sources to construct the RLF. We postulate that all sources start out with an FRII-type morphology. Weaker jets subsequently disrupt within the quasi-constant density cores of their host galaxies and develop turbulent lobes of type FRI. With this model we recover the slopes of the power laws and the break luminosity of the RLF determined from observations. The rate at which AGN with jets of jet power $Q$ appear in the universe is found to be proportional to $Q^{-1.6}$. The model also roughly predicts the distribution of the radio lobe sizes for FRII-type objects, if the radio luminosity of the turbulent jets drops significantly at the point of disruption. We show that our model is consistent with recent ideas of two distinct accretion modes in jet-producing AGN, if radiative efficiency of the accretion process is correlated with jet power.Comment: 13 pages, 1 figure, accepted by MNRA

6C radio galaxies at z~1: The influence of radio power on the alignment effect

Powerful radio galaxies often display enhanced optical/UV continuum emission and extended emission line regions, elongated and aligned with the radio jet axis. The expansion of the radio source strongly affects the gas clouds in the surrounding IGM, and the kinematic and ionization properties of the extended emission line regions display considerable variation over the lifetime of individual sources, as well as with cosmic epoch. We present the results of deep rest-frame UV and optical imaging and UV spectroscopy of high redshift 6C radio galaxies. The interdependence of the host galaxy and radio source properties are discussed, considering: (i) the relative contribution of shocks associated with the expanding radio source to the observed emission line gas kinematics, and their effect on the ionization state of the gas; (ii) the similarities and differences between the morphologies of the host galaxies and aligned emission for a range of radio source powers; and (iii) the influence of radio power on the strength of the observed alignment effect.Comment: LaTeX, 6 pages, 5 figures, Elsevier Science format. To appear in "Radio galaxies: past, present & future". eds. M. Jarvis et al., Leiden, Nov 200

Evolution of AGN Space Densities and the FR Dichotomy

We focus on a comparison of the space densities of FRI and FRII extended radio sources at different epochs, and find that FRI and FRII sources show similar space density enhancements in various redshift ranges, possibly implying a common evolution.Comment: IAU Symposium 267 Proceeding - 1 pag

Apocalypticisim in the fiction of William S. Burroughs, J.G. Ballard, and Thomas Pynchon.

Apocalypse should not be thought of as merely a synonym for chaos or disaster or cataclysmic upheaval; more properly we should think of disclosure, unveiling and revelation. The exact status of literary apocalyptic is the subject of some debate, and in an attempt to help clarify matters an introductory historical survey examines both the formal characteristics of apocalypse and the various critical positions taken in regard to the genre's social influence. Texts considered in the chapter include the Revelation of John and Thomas Pynchon's short story Entropy (1959); theoretical works by Frank Kermode, John Barth, and Jean Baudrillard (amongst others) are also discussed. Chapter One traces the development of William S. Burroughs's apocalyptic sensibility through readings of his correspondence with Allen Ginsberg and the novel The Naked Lunch (1959); the latter's apocalyptic title referring to the "frozen moment when everyone sees what is on the end of every fork". Chapter Two considers Burroughs's experiments with the "cut-ups" and their application in a number of texts, most notably Nova Express (1964). Chapter Three is concerned with Burroughs's work in the 1970s and 80s, and specifically his concept of Here to Go, a theory of mutability presented as a transcendental antidote to the threat of nuclear annihilation (the author's alleged misogyny and the views of radical US feminists are also taken into account). Chapters Four and Five explore the apocalyptic fiction of J. G. Ballard; topics covered include Ballard's concept of inner space, his debt to Surrealism, and the coded landscapes of his more experimental texts; in particular the "condensed novels" which comprise The Atrocity Exhibition (1970). A concluding chapter returns to the work of Thomas Pynchon, offering a reading of Gravity's Rainbow (1973) which allows us to consider his treatment of such related themes as Paranoia, Holocaust, Apocalypse, and finally, Counterforce

Clustering around radio galaxies at z~1.5

The importance of studying old elliptical galaxies at redshift z ~ 1.5 is reviewed, considering both what can be learned by extending studies of the evolution of cluster galaxy scaling relations to earlier cosmic epochs, and the age-dating of old elliptical galaxies at high redshifts. Following this, the first results are provided of an on-going project to find such distant elliptical galaxies, through an investigation of the cluster environments of powerful radio sources with redshifts 1.44 < z < 1.7. These studies show a considerable excess of red galaxies in the radio sources fields, with the magnitudes (K >~ 17.5) and colours (R-K > 4) expected of old passively evolving galaxies at the radio source redshift. The red galaxy overdensities are found on two different scales around the radio sources; a pronounced small-scale peak at radial distances of <~ 150 kpc, and a weaker large-scale excess extending out to 1 - 1.5 Mpc. The presence and richness of these red galaxy excesses varies considerably from source to source. An interpretation of these results is provided.Comment: LaTeX, 6 pages, Elsevier Science format. To appear in "Radio galaxies: past, present & future". eds. M. Jarvis et al., Leiden, Nov 200

Māori values for Māori business: Cultural Capital in Indigenous Organisations

Cultural capital holds much prospect as a theoretical concept for engaging core Indigenous Māori values in capitalistic endeavours, yet it still awaits satisfactory interpretation by Indigenous Māori management theorists researching in Aotearoa New Zealand. Particularly, little is known about how Māori values, beliefs and perspectives impact managerial decision-making to create competitive advantage locally, nationally and internationally. Kaupapa Māori Research has been cited in the research literature as an ideal method for exploring the little known experiences of Māori managers employing the concept of cultural capital. This paper argues that a particular variation of Kaupapa Māori Research be employed to collect and interpret empirical material collected in face-to-face interviews with managers in Māori-centred (tribal and family -based) organisations operating in Aotearoa New Zealand

Erratum: Luminosity function, sizes and FR dichotomy of radio-loud AGN

This erratum corrects a number of formulae containing mistakes in the paper 'Luminosity function, sizes and FR dichotomy of radio-loud AGN', 2007, MNRAS, v. 381, p.1548. The corrections do not alter any of the conclusions in the original paper.Comment: single page, no figures, erratum to MNRAS, 2007, v. 381, p. 154