277 research outputs found

    The democratic engagement of Britain's ethnic minorities

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    Democratic engagement is a multi-faceted phenomenon that embraces citizens' involvement with electoral politics, their participation in ‘conventional’ extra-parliamentary political activity, their satisfaction with democracy and trust in state institutions, and their rejection of the use of violence for political ends. Evidence from the 2010 BES and EMBES shows that there are important variations in patterns of democratic engagement across Britain's different ethnic-minority groups and across generations. Overall, ethnic-minority engagement is at a similar level to and moved by the same general factors that influence the political dispositions of whites. However, minority democratic engagement is also strongly affected by a set of distinctive ethnic-minority perceptions and experiences, associated particularly with discrimination and patterns of minority and majority cultural engagement. Second-generation minorities who grew up in Britain are less, rather than more, likely to be engaged

    Nuclear X-ray properties of the peculiar radio-loud hidden AGN 4C+29.30

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    We present results from a study of a nuclear emission of a nearby radio galaxy, 4C+29.30, over a broad 0.5-200 keV X-ray band. This study used new XMM-Newton (~17 ksec) and Chandra (~300 ksec) data, and archival Swift/BAT data from the 58-month catalog. The hard (>2 keV) X-ray spectrum of 4C+29.30 can be decomposed into an intrinsic hard power-law (Gamma ~ 1.56) modified by a cold absorber with an intrinsic column density N_{H,z} ~ 5x10^{23} cm^{-2}, and its reflection (|Omega/2pi| ~ 0.3) from a neutral matter including a narrow iron Kalpha emission line at the rest frame energy ~6.4 keV. The reflected component is less absorbed than the intrinsic one with an upper limit on the absorbing column of N^{refl}_{H,z} < 2.5x10^{22} cm^{-2}. The X-ray spectrum varied between the XMM-Newton and Chandra observations. We show that a scenario invoking variations of the normalization of the power-law is favored over a model with variable intrinsic column density. X-rays in the 0.5-2 keV band are dominated by diffuse emission modeled with a thermal bremsstrahlung component with temperature ~0.7 keV, and contain only a marginal contribution from the scattered power-law component. We hypothesize that 4C+29.30 belongs to a class of `hidden' AGN containing a geometrically thick torus. However, unlike the majority of them, 4C+29.30 is radio-loud. Correlations between the scattering fraction and Eddington luminosity ratio, and the one between black hole mass and stellar velocity dispersion, imply that 4C+29.30 hosts a black hole with ~10^8 M_{Sun} mass.Comment: 13 pages, 5 figures, ApJ in pres

    Hard X-ray spectral variability of the brightest Seyfert AGN in the Swift/BAT sample

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    Aims: We used data from the 58 month long, continuous Swift/Burst Alert Telescope (BAT) observations of the five brightest Seyfert galaxies at hard X-rays, to study their flux and spectral variability in the 20-100 keV energy band. The column density in these objects is less than 10^24 cm-2, which implies that the Swift/BAT data allow us to study the "true" variability of the central source. Results: All objects show significant variations, with an amplitude which is similar to the AGN variability amplitude at energies below 10 keV. We found evidence for an anti-correlation between variability amplitude and black hole mass. The light curves in both bands are well correlated, with no significant delays on time scales as short as 2 days. NGC 4151 and NGC 2110 do not show spectral variability, but we found a significant anti-correlation between hardness ratios and source flux in NGC 4388 (and NGC 4945, IC 4329, to a lesser extent). This "softer when brighter" behaviour is similar to what has been observed at energies below 10 keV, and cannot be explained if the continuum varies only in flux; the intrinsic shape should also steepen with increasing flux. Conclusions: The presence of significant flux variations indicate that the central source in these objects is intrinsically variable on time scales as short as 1-2 days. The intrinsic slope of the continuum varies with the flux (at least in NGC 4388). The positive "spectral slope-flux" correlation can be explained if the temperature of the hot corona decreases with increasing flux. The lack of spectral variations in two objects, could be due to the fact that they may operate in a different "state", as their accretion rate is less than 1% of the Eddington limit (significantly smaller than the rate of the other three objects in the sample).Comment: Accepted (29/10/11) for publication in A&A (12 pages, containing 14 figures and 2 tables). (Abstract shortened --see link for the complete one

    Deep Chandra X-ray Imaging of a Nearby Radio Galaxy 4C+29.30: X-ray/Radio Connection

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    We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z=0.0647). The Chandra image resolves structures on sub-arcsec to arcsec scales, revealing complex X-ray morphology and detecting the main radio features: the nucleus, a jet, hotspots, and lobes. The nucleus is absorbed (N(H)=3.95 (+0.27/-0.33)x10^23 atoms/cm^2) with an unabsorbed luminosity of L(2-10 keV) ~ (5.08 +/-0.52) 10^43 erg/s characteristic of Type 2 AGN. Regions of soft (<2 keV) X-ray emission that trace the hot interstellar medium (ISM) are correlated with radio structures along the main radio axis indicating a strong relation between the two. The X-ray emission beyond the radio source correlates with the morphology of optical line-emitting regions. We measured the ISM temperature in several regions across the galaxy to be kT ~ 0.5 with slightly higher temperatures (of a few keV) in the center and in the vicinity of the radio hotspots. Assuming these regions were heated by weak shocks driven by the expanding radio source, we estimated the corresponding Mach number of 1.6 in the southern regions. The thermal pressure of the X-ray emitting gas in the outermost regions suggest the hot ISM is slightly under-pressured with respect to the cold optical-line emitting gas and radio-emitting plasma, which both seem to be in a rough pressure equilibrium. We conclude that 4C+29.30 displays a complex view of interactions between the jet-driven radio outflow and host galaxy environment, signaling feedback processes closely associated with the central active nucleus.Comment: ApJ in pres

    An XMM-Newton view of the `bare' nucleus of Fairall 9

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    We present the spectral results from a 130 ks observation, obtained from the X-ray Multi-Mirror Mission-Newton (XMM-Newton) observatory, of the type I Seyfert galaxy Fairall 9. An X-ray hardness-ratio analysis of the light-curves, reveals a `softer-when-brighter' behaviour which is typical for radio-quiet type I Seyfert galaxies. Moreover, we analyse the high spectral-resolution data of the reflection grating spectrometer and we did not find any significant evidence supporting the presence of warm-absorber in the low X-ray energy part of the source's spectrum. This means that the central nucleus of Fairall 9 is `clean' and thus its X-ray spectral properties probe directly the physical conditions of the central engine. The overall X-ray spectrum in the 0.5-10 keV energy-range, derived from the EPIC data, can be modelled by a relativistically blurred disc-reflection model. This spectral model yields for Fairall 9 an intermediate black-hole best-fit spin parameter of α=0.390.30+0.48\alpha=0.39^{+0.48}_{-0.30}.Comment: Accepted for publication in MNRAS. The paper contains 11 figures and 1 tabl

    Characterizing a new class of variability in GRS 1915+105 with simultaneous INTEGRAL/RXTE observations

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    We report on the analysis of 100 ks INTEGRAL observations of the Galactic microquasar GRS 1915+105. We focus on INTEGRAL Revolution number 48 when the source was found to exhibit a new type of variability as preliminarily reported in Hannikainen et al. (2003). The variability pattern, which we name ξ\xi, is characterized by a pulsing behaviour, consisting of a main pulse and a shorter, softer, and smaller amplitude precursor pulse, on a timescale of 5 minutes in the JEM-X 3-35 keV lightcurve. We also present simultaneous RXTE data. From a study of the individual RXTE/PCA pulse profiles we find that the rising phase is shorter and harder than the declining phase, which is opposite to what has been observed in other otherwise similar variability classes in this source. The position in the colour-colour diagram throughout the revolution corresponds to State A (Belloni et al. 2000) but not to any previously known variability class. We separated the INTEGRAL data into two subsets covering the maxima and minima of the pulses and fitted the resulting two broadband spectra with a hybrid thermal--non-thermal Comptonization model. The fits show the source to be in a soft state characterized by a strong disc component below ~6 keV and Comptonization by both thermal and non-thermal electrons at higher energies.Comment: Accepted for publication in A&A. 11 pages, 10 figures, 4 in colour. Original figures can be found at http://www.astro.helsinki.fi/~diana/grs1915_rev48. Author affiliations correcte

    Accretion and ejection in black-hole X-ray transients

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    Aims: We summarize the current observational picture of the outbursts of black-hole X-ray transients (BHTs), based on the evolution traced in a hardness-luminosity diagram (HLD), and we offer a physical interpretation. Methods: The basic ingredient in our interpretation is the Poynting-Robertson Cosmic Battery (PRCB, Contopoulos & Kazanas 1998), which provides locally the poloidal magnetic field needed for the ejection of the jet. In addition, we make two assumptions, easily justifiable. The first is that the mass-accretion rate to the black hole in a BHT outburst has a generic bell-shaped form. This is guaranteed by the observational fact that all BHTs start their outburst and end it at the quiescent state. The second assumption is that at low accretion rates the accretion flow is geometrically thick, ADAF-like, while at high accretion rates it is geometrically thin. Results: Both, at the beginning and the end of an outburst, the PRCB establishes a strong poloidal magnetic field in the ADAF-like part of the accretion flow, and this explains naturally why a jet is always present in the right part of the HLD. In the left part of the HLD, the accretion flow is in the form of a thin disk, and such a disk cannot sustain a strong poloidal magnetic filed. Thus, no jet is expected in this part of the HLD. The counterclockwise traversal of the HLD is explained as follows: the poloidal magnetic field in the ADAF forces the flow to remain ADAF and the source to move upwards in the HLD rather than to turn left. Thus, the history of the system determines the counterclockwise traversal of the HLD. As a result, no BHT is expected to ever traverse the entire HLD curve in the clockwise direction. Conclusions: We offer a physical interpretation of accretion and ejection in BHTs with only one parameter, the mass transfer rate.Comment: Accepted for publication in A&

    Accretion, ejection and reprocessing in supermassive black holes

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    This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of active galactic nuclei. For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timin

    From incomer to insider: The development of the TRANSPEC model - A systematic review of the factors influencing the effective rapid and early career TRANsition to a nursing SPECiality in differing contexts of practice

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    (c) The Author/sObjective Shortages in the speciality nursing workforce, both nationally and internationally are driving the need for the development of an evidence-based model to inform recruitment and retention into speciality nursing practice. This study aimed to identify the factors influencing rapid and early career transition into speciality nursing practice. Methods A comprehensive systematic review of the literature was undertaken using a convergent qualitative synthesis design where results from qualitative, quantitative and mixed methods studies were transformed into qualitative findings. Databases included CINAHL, Medline, Scopus and PsycINFO. Search terms were: nurse, early career, rapid career, transition, specialty, and Medical Subject Heading terms included: professional development and educational, nursing, and continuing. Using validated tools, papers were independently assessed by a minimum of two reviewers. Results Twenty-three research articles were included. There were no randomized control trials. Through thematic analysis and matrix mapping of the results, the TRANSPEC model was developed. The model outlines three phases of transition: pre-entry, incomer and insider. There has been little focus on pre-entry with programs being designed at the incomer and insider phases. Impacting on these phases are three concepts: the self (professional and personal), the transition processes (informal and formal) and a sense of belonging. The overarching theme influencing the phases and concepts is the context of practice. Enablers and inhibitors influence successful transition and therefore impact on recruitment and retention. Each nurse’s transition is influenced by time. Conclusions For successful transition, the enablers and inhibitors impacting on the three concepts, phases and the context of practice need to be considered when developing any program. It is apparent that while previous studies have focused on the transition processes, such as curricula, the development of the self and a sense of belonging are also essential to successful transition. Further studies should include the pre-entry phase

    Modelling spectral and timing properties of accreting black holes: the hybrid hot flow paradigm

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    The general picture that emerged by the end of 1990s from a large set of optical and X-ray, spectral and timing data was that the X-rays are produced in the innermost hot part of the accretion flow, while the optical/infrared (OIR) emission is mainly produced by the irradiated outer thin accretion disc. Recent multiwavelength observations of Galactic black hole transients show that the situation is not so simple. Fast variability in the OIR band, OIR excesses above the thermal emission and a complicated interplay between the X-ray and the OIR light curves imply that the OIR emitting region is much more compact. One of the popular hypotheses is that the jet contributes to the OIR emission and even is responsible for the bulk of the X-rays. However, this scenario is largely ad hoc and is in contradiction with many previously established facts. Alternatively, the hot accretion flow, known to be consistent with the X-ray spectral and timing data, is also a viable candidate to produce the OIR radiation. The hot-flow scenario naturally explains the power-law like OIR spectra, fast OIR variability and its complex relation to the X-rays if the hot flow contains non-thermal electrons (even in energetically negligible quantities), which are required by the presence of the MeV tail in Cyg X-1. The presence of non-thermal electrons also lowers the equilibrium electron temperature in the hot flow model to <100 keV, making it more consistent with observations. Here we argue that any viable model should simultaneously explain a large set of spectral and timing data and show that the hybrid (thermal/non-thermal) hot flow model satisfies most of the constraints.Comment: 26 pages, 13 figures. To be published in the Space Science Reviews and as hard cover in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher
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