873 research outputs found

    Accounting for decarbonisation and reducing capital at risk in the S&P500

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    This document is the Accepted Manuscript version of the following article: Colin Haslam, Nick Tsitsianis, Glen Lehman, Tord Andersson, and John Malamatenios, ‘Accounting for decarbonisation and reducing capital at risk in the S&P500’, Accounting Forum, Vol. 42 91): 119-129, March 2018. Under embargo until 7 August 2019. The final, definitive version is available online at doi: https://doi.org/10.1016/j.accfor.2018.01.004.This article accounts for carbon emissions in the S&P 500 and explores the extent to which capital is at risk from decarbonising value chains. At a global level it is proving difficult to decouple carbon emissions from GDP growth. Top-down legal and regulatory arrangements envisaged by the Kyoto Protocol are practically redundant given inconsistent political commitment to mitigating global climate change and promoting sustainability. The United Nations Environment Programme (UNEP) and European Commission (EC) are promoting the role of financial markets and financial institutions as drivers of behavioural change mobilising capital allocations to decarbonise corporate activity.Peer reviewe

    The Stellar Halos of Massive Elliptical Galaxies II: Detailed Abundance Ratios at Large Radius

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    We study the radial dependence in stellar populations of 33 nearby early-type galaxies with central stellar velocity dispersions sigma* > 150 km/s. We measure stellar population properties in composite spectra, and use ratios of these composites to highlight the largest spectral changes as a function of radius. Based on stellar population modeling, the typical star at 2 R_e is old (~10 Gyr), relatively metal poor ([Fe/H] -0.5), and alpha-enhanced ([Mg/Fe]~0.3). The stars were made rapidly at z~1.5-2 in shallow potential wells. Declining radial gradients in [C/Fe], which follow [Fe/H], also arise from rapid star formation timescales due to declining carbon yields from low-metallicity massive stars. In contrast, [N/Fe] remains high at large radius. Stars at large radius have different abundance ratio patterns from stars in the center of any present-day galaxy, but are similar to Milky Way thick disk stars. Our observations are thus consistent with a picture in which the stellar outskirts are built up through minor mergers with disky galaxies whose star formation is truncated early (z~1.5-2).Comment: ApJ in press, 12 pages, 6 figure

    Rings of Dark Matter in Collisions Between Clusters of Galaxies

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    Several lines of evidence suggest that the galaxy cluster Cl0024+17, an apparently relaxed system, is actually a collision of two clusters, the interaction occurring along our line of sight. Recent lensing observations suggest the presence of a ring-like dark matter structure, which has been interpreted as the result of such a collision. In this paper we present NN-body simulations of cluster collisions along the line of sight to investigate the detectability of such features. We use realistic dark matter density profiles as determined from cosmological simulations. Our simulations show a "shoulder" in the dark matter distribution after the collision, but no ring feature even when the initial particle velocity distribution is highly tangentially anisotropic (σθ/σr>>1\sigma_\theta/\sigma_r >> 1). Only when the initial particle velocity distribution is circular do our simulations show such a feature. Even modestly anisotropic velocity distributions are inconsistent with the halo velocity distributions seen in cosmological simulations, and would require highly fine-tuned initial conditions. Our investigation leaves us without an explanation for the dark matter ring-like feature in Cl 0024+17 suggested by lensing observations.Comment: 7 pages (emulateapj), 9 figures. Expanded figures and text to match accepted versio

    Linking Environmental Sustainability and Healthcare: The Effects of an Energy Saving Intervention in Two Hospitals

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    Set in a real organisational setting, this study examines the challenges of implementing environmentally sustainable behaviour in healthcare. It evaluates the success of a real energy saving behaviour change intervention, based on social marketing principles, which targeted the employees of two National Health Service (NHS) hospitals. It also explores the intervention benefits for three key stakeholders: the organisation/hospitals, hospital employees and patients. A rich secondary dataset containing actual workplace behaviour measures (collected via observations) and self-reported data from employee interviews and patient questionnaires is used for this purpose. The intervention encouraged three employee energy saving actions (called TLC actions): (1) Turn off machines, (2) Lights out when not needed, and (3) Close doors when possible; which led to energy savings and carbon reduction for the two hospitals. Hospital employees reported a greater level of work efficiency as a result of engaging in TLC actions, which increased the 'quiet time' periods in both hospitals. Indirectly, employees' TLC actions also improved patients' quality of sleep (which in turn is positively associated with greater patient hospital experience satisfaction). These findings shed light on the benefits of social marketing interventions targeting energy saving behaviour change for multiple stakeholders in healthcare organisations. They also illustrate connections between environmental sustainability and social and political pillars of corporate social responsibility. Additionally, organisational culture was highlighted as a key challenge in changing practices. To encourage long-term sustainable behaviour, this study recommends a pre-intervention assessment of infrastructure and equipment, the communication of expected benefits to motivate higher involvement of employees, the need for internal green champions and the dissemination of post-intervention feedback on various energy saving and patient indicators

    A Search for Binary Active Galactic Nuclei: Double-Peaked [OIII] AGN in the Sloan Digital Sky Survey

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    We present AGN from the Sloan Digital Sky Survey (SDSS) having double-peaked profiles of [OIII] 5007,4959 and other narrow emission-lines, motivated by the prospect of finding candidate binary AGN. These objects were identified by means of a visual examination of 21,592 quasars at z < 0.7 in SDSS Data Release 7 (DR7). Of the spectra with adequate signal-to-noise, 148 spectra exhibit a double-peaked [OIII] profile. Of these, 86 are Type 1 AGN and 62 are Type 2 AGN. Only two give the appearance of possibly being optically resolved double AGN in the SDSS images, but many show close companions or signs of recent interaction. Radio-detected quasars are three times more likely to exhibit a double-peaked [OIII] profile than quasars with no detected radio flux, suggesting a role for jet interactions in producing the double-peaked profiles. Of the 66 broad line (Type 1) AGN that are undetected in the FIRST survey, 0.9% show double peaked [OIII] profiles. We discuss statistical tests of the nature of the double-peaked objects. Further study is needed to determine which of them are binary AGN rather than disturbed narrow line regions, and how many additional binaries may remain undetected because of insufficient line-of-sight velocity splitting. Previous studies indicate that 0.1% of SDSS quasars are spatially resolved binaries, with typical spacings of ~10 to 100 kpc. If a substantial fraction of the double-peaked objects are indeed binaries, then our results imply that binaries occur more frequently at smaller separations (< 10 kpc). This suggests that simultaneous fueling of both black holes is more common as the binary orbit decays through these spacings.Comment: 33 pages, 5 figures, LaTeX. Major revisions. Accepted for publication in ApJ

    Ring Formation from an Oscillating Black Hole

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    Massive black hole (BH) mergers can result in the merger remnant receiving a "kick", of order 200 km s1^{-1} or more, which will cause the remnant to oscillate about the galaxy centre. Here we analyze the case where the BH oscillates through the galaxy centre perpendicular or parallel to the plane of the galaxy for a model galaxy consisting of an exponential disk, a Plummer model bulge, and an isothermal dark matter halo. For the perpendicular motion we find that there is a strong resonant forcing of the disk radial motion near but somewhat less than the "resonant radii" rRr_R where the BH oscillation frequency is equal one-half, one-fourth, (1/6, etc.) of the radial epicyclic frequency in the plane of the disk. Near the resonant radii there can be a strong enhancement of the radial flow and disk density which can lead to shock formation. In turn the shock may trigger the formation of a ring of stars near rRr_R. As an example, for a BH mass of 108M10^8 M_\odot and a kick velocity of 150 km s1^{-1}, we find that the resonant radii lie between 0.2 and 1 kpc. For BH motion parallel to the plane of the galaxy we find that the BH leaves behind it a supersonic wake where star formation may be triggered. The shape of the wake is calculated as well as the slow-down time of the BH. The differential rotation of the disk stretches the wake into ring-like segments.Comment: 7 pages, 7 figure

    HST Observations of the Double-Peaked Emission Lines in the Seyfert Galaxy Markarian 78: Mass Outflows from a Single AGN

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    Previous ground based observations of the Seyfert 2 galaxy Mrk 78 revealed a double set of emission lines, similar to those seen in several AGN from recent surveys. Are the double lines due to two AGN with different radial velocities in the same galaxy, or are they due to mass outflows from a single AGN?We present a study of the outflowing ionized gas in the resolved narrow-line region (NLR) of Mrk 78 using observations from Space Telescope Imaging Spectrograph (STIS) and Faint Object Camera (FOC) aboard the Hubble Space Telescope(HST) as part of an ongoing project to determine the kinematics and geometries of active galactic nuclei (AGN) outflows. From the spectroscopic information, we deter- mined the fundamental geometry of the outflow via our kinematics modeling program by recreating radial velocities to fit those seen in four different STIS slit positions. We determined that the double emission lines seen in ground-based spectra are due to an asymmetric distribution of outflowing gas in the NLR. By successfully fitting a model for a single AGN to Mrk 78, we show that it is possible to explain double emission lines with radial velocity offsets seen in AGN similar to Mrk 78 without requiring dual supermassive black holes.Comment: 22 pages, 7 figures (2 color), accepted for publication in The Astrophysical Journa

    Investigating the evolution of the dual AGN system ESO~509-IG066

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    We analyze the evolution of the dual AGN in ESO 509-IG066, a galaxy pair located at z=0.034 whose nuclei are separated by 11 kpc. Previous observations with XMM-Newton on this dual AGN found evidence for two moderately obscured (NH1022N_H\sim10^{22} cm2^{-2}) X-ray luminous (LX1043L_X\sim10^{43} erg/s) nuclear sources. We present an analysis of subsequent Chandra, NuSTAR and Swift/XRT observations that show one source has dropped in flux by a factor of 10 between 2004 and 2011, which could be explained by either an increase in the absorbing column or an intrinsic fading of the central engine possibly due to a decrease in mass accretion. Both of these scenarios are predicted by galaxy merger simulations. The source which has dropped in flux is not detected by NuSTAR, which argues against absorption, unless it is extreme. However, new Keck/LRIS optical spectroscopy reveals a previously unreported broad H-alpha line which is highly unlikely to be visible under the extreme absorption scenario. We therefore conclude that the black hole in this nucleus has undergone a dramatic drop in accretion rate. From AO-assisted near-infrared integral-field spectroscopy of the other nucleus, we find evidence that the galaxy merger is having a direct effect on the kinematics of the gas close to the nucleus of the galaxy, providing a direct observational link between the galaxy merger and the mass accretion rate on to the black hole.Comment: Accepted for publication in Ap

    Adaptive Optics Imaging of QSOs with Double-Peaked Narrow Lines: Are they Dual AGNs?

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    Active galaxies hosting two accreting and merging super-massive black holes (SMBHs) -- dual Active Galactic Nuclei (AGN) -- are predicted by many current and popular models of black hole-galaxy co-evolution. We present here the results of a program that has identified a set of probable dual AGN candidates based on near Infra-red (NIR) Laser Guide-Star Adaptive Optics (LGS AO) imaging with the Keck II telescope. These candidates are selected from a complete sample of radio-quiet Quasi-stellar Objects (QSOs) drawn from the Sloan Digital Sky Survey (SDSS), which show double-peaked narrow AGN emission lines. Of the twelve AGNs imaged, we find six with double galaxy structure, of which four are in galaxy mergers. We measure the ionization of the two velocity components in the narrow AGN lines to test the hypothesis that both velocity components come from an active nucleus. The combination of a well-defined parent sample and high-quality imaging allows us to place constraints on the fraction of SDSS QSOs that host dual accreting black holes separated on kiloparsec (kpc) scales: ~0.3%-0.65%. We derive from this fraction the time spent in a QSO phase during a typical merger and find a value that is much lower than estimates that arise from QSO space densities and galaxy merger statistics. We discuss possible reasons for this difference. Finally, we compare the SMBH mass distributions of single and dual AGN and find little difference between the two within the limited statistics of our program, hinting that most SMBH growth happens in the later stages of a merger process.Comment: 9 pages, 4 figures, 1 table; accepted to the Astrophysical Journa

    Informing investment to reduce inequalities: a modelling approach

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    Background: Reducing health inequalities is an important policy objective but there is limited quantitative information about the impact of specific interventions. Objectives: To provide estimates of the impact of a range of interventions on health and health inequalities. Materials and methods: Literature reviews were conducted to identify the best evidence linking interventions to mortality and hospital admissions. We examined interventions across the determinants of health: a ‘living wage’; changes to benefits, taxation and employment; active travel; tobacco taxation; smoking cessation, alcohol brief interventions, and weight management services. A model was developed to estimate mortality and years of life lost (YLL) in intervention and comparison populations over a 20-year time period following interventions delivered only in the first year. We estimated changes in inequalities using the relative index of inequality (RII). Results: Introduction of a ‘living wage’ generated the largest beneficial health impact, with modest reductions in health inequalities. Benefits increases had modest positive impacts on health and health inequalities. Income tax increases had negative impacts on population health but reduced inequalities, while council tax increases worsened both health and health inequalities. Active travel increases had minimally positive effects on population health but widened health inequalities. Increases in employment reduced inequalities only when targeted to the most deprived groups. Tobacco taxation had modestly positive impacts on health but little impact on health inequalities. Alcohol brief interventions had modestly positive impacts on health and health inequalities only when strongly socially targeted, while smoking cessation and weight-reduction programmes had minimal impacts on health and health inequalities even when socially targeted. Conclusions: Interventions have markedly different effects on mortality, hospitalisations and inequalities. The most effective (and likely cost-effective) interventions for reducing inequalities were regulatory and tax options. Interventions focused on individual agency were much less likely to impact on inequalities, even when targeted at the most deprived communities
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