40,764 research outputs found

    Consumers' expenditure on sport in the UK: Increased spending or under-estimation?

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    The paper will present the findings of a consumer survey carried out in Sheffield in 1996/97 to demonstrate that spending on sport-related goods and services in the UK has been underestimated. It will argue that consumers’ expenditure on sport by residents in Sheffield was greater than anticipated from national estimates, largely due to methodological reasons rather than increased spending. The paper will illustrate that conventional approaches, which use published data sources to measure sport-related expenditure are firstly, not a valid measure of sports spending and secondly, have omitted several items of sport-related expenditure from current estimates. The paper will explore the implications of these findings for policy makers and managers of sport and leisure services and will suggest that a review of methods used to calculate consumer spending on sport is required in the future.</p

    Stellar and Molecular Gas Kinematics of NGC1097: Inflow Driven by a Nuclear Spiral

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    We present spatially resolved distributions and kinematics of the stars and molecular gas in the central 320pc of NGC1097. The stellar continuum confirms the previously reported 3-arm spiral pattern extending into the central 100pc. The stellar kinematics and the gas distribution imply this is a shadowing effect due to extinction by gas and dust in the molecular spiral arms. The molecular gas kinematics show a strong residual (i.e. non-circular) velocity, which is manifested as a 2-arm kinematic spiral. Linear models indicate that this is the line-of-sight velocity pattern expected for a density wave in gas that generates a 3-arm spiral morphology. We estimate the inflow rate along the arms. Using hydrodynamical models of nuclear spirals, we show that when deriving the accretion rate into the central region, outflow in the disk plane between the arms has to be taken into account. For NGC1097, despite the inflow rate along the arms being ~1.2Msun/yr, the net gas accretion rate to the central few tens of parsecs is much smaller. The numerical models indicate that the inflow rate could be as little as ~0.06Msun/yr. This is sufficient to generate recurring starbursts, similar in scale to that observed, every 20-150Myr. The nuclear spiral represents a mechanism that can feed gas into the central parsecs of the galaxy, with the gas flow sustainable for timescales of a Gigayear.Comment: accepted by Ap

    Are There Magnetars in High Mass X-ray Binaries? The Case of SuperGiant Fast X-Ray Transients

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    In this paper we survey the theory of wind accretion in high mass X-ray binaries hosting a magnetic neutron star and a supergiant companion. We concentrate on the different types of interaction between the inflowing wind matter and the neutron star magnetosphere that are relevant when accretion of matter onto the neutron star surface is largely inhibited; these include the inhibition through the centrifugal and magnetic barriers. Expanding on earlier work, we calculate the expected luminosity for each regime and derive the conditions under which transition from one regime to another can take place. We show that very large luminosity swings (~10^4 or more on time scales as short as hours) can result from transitions across different regimes. The activity displayed by supergiant fast X-ray transients, a recently discovered class of high mass X-ray binaries in our galaxy, has often been interpreted in terms of direct accretion onto a neutron star immersed in an extremely clumpy stellar wind. We show here that the transitions across the magnetic and/or centrifugal barriers can explain the variability properties of these sources as a results of relatively modest variations in the stellar wind velocity and/or density. According to this interpretation we expect that supergiant fast X-ray transients which display very large luminosity swings and host a slowly spinning neutron star are characterized by magnetar-like fields, irrespective of whether the magnetic or the centrifugal barrier applies. Supergiant fast X-ray transients might thus provide a new opportunity to detect and study magnetars in binary systems.Comment: Accepted for publication in ApJ. 16 pages, 6 figure

    The detection of FIR emission from high redshift star-forming galaxies in the ECDF-S

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    ABRIDGED: We have used the LABOCA Survey of the ECDF-S (LESS) to investigate rest-frame FIR emission from typical SF systems (LBGs) at redshift 3, 4, and 5. We initially concentrate on LBGs at z~3 and select three subsamples on stellar mass, extinction corrected SF and rest-frame UV-magnitude. We produce composite 870micron images of the typical source in our subsamples, obtaining ~4sigma detections and suggesting a correlation between FIR luminosity and stellar mass. We apply a similar procedure to our full samples at z~3, 4, 4.5 and 5 and do not obtain detections - consistent with a simple scaling between FIR luminosity and stellar mass. In order to constrain the FIR SED of these systems we explore their emission at multiple wavelengths spanning the peak of dust emission at z~3 using the Herschel SPIRE observations of the field. We obtain detections at multiple wavelengths for both our stellar mass and UV-magnitude selected samples, and find a best-fit SED with T_dust in the ~33-41K range. We calculate L_FIR, obscured SFRs and M_dust, and find that a significant fraction of SF in these systems is obscured. Interestingly, our extinction corrected SFR sample does not display the large FIR fluxes predicted from its red UV-spectral slope. This suggests that the method of assuming an intrinsic UV-slope and correcting for dust attenuation may be invalid for this sample - and that these are not in fact the most actively SF systems. All of our z~3 samples fall on the `main sequence' of SF galaxies at z~3 and our detected subsamples are likely to represent the high obscuration end of LBGs at their epoch. We compare the FIR properties of our subsamples with various other populations, finding that our stellar mass selected sample shows similar FIR characteristics to SMGs at the same epoch and therefore potentially represents the low L_FIR end of the high redshift FIR luminosity function.Comment: 18 pages, 10 figure, MNRAS accepted, corrected typos, acknowledgements adde

    NuSTAR hard X-ray data and Gemini 3D spectra reveal powerful AGN and outflow histories in two low-redshift Lyman-α\alpha blobs

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    We have shown that Lyman-α\alpha blobs (LABs) may still exist even at z∼0.3z\sim0.3, about 7 billion years later than most other LABs known (Schirmer et al. 2016). Their luminous Lyα\alpha and [OIII] emitters at z∼0.3z\sim0.3 offer new insights into the ionization mechanism. This paper focuses on the two X-ray brightest LABs at z∼0.3z\sim0.3, SDSS J0113++0106 (J0113) and SDSS J1155−-0147 (J1155), comparable in size and luminosity to `B1', one of the best-studied LABs at z≳z \gtrsim 2. Our NuSTAR hard X-ray (3--30 keV) observations reveal powerful active galactic nuclei (AGN) with L2−10  keV=(0.5L_{2-10{\;\rm keV}}=(0.5--3)×10443)\times10^{44} erg cm−2^{-2} s−1^{-1}. J0113 also faded by a factor of ∼5\sim 5 between 2014 and 2016, emphasizing that variable AGN may cause apparent ionization deficits in LABs. Joint spectral analyses including Chandra data constrain column densities of NH=5.1−3.3+3.1×1023N_{\rm H}=5.1^{+3.1}_{-3.3}\times10^{23} cm−2^{-2} (J0113) and NH=6.0−1.1+1.4×1022N_{\rm H}=6.0^{+1.4}_{-1.1}\times10^{22} cm−2^{-2} (J1155). J0113 is likely buried in a torus with a narrow ionization cone, but ionizing radiation is also leaking in other directions as revealed by our Gemini/GMOS 3D spectroscopy. The latter shows a bipolar outflow over 1010 kpc, with a peculiar velocity profile that is best explained by AGN flickering. X-ray analysis of J1155 reveals a weakly absorbed AGN that may ionize over a wide solid angle, consistent with our 3D spectra. Extinction corrected [OIII] log-luminosities are high, ∼43.6\sim43.6. The velocity dispersions are low, ∼100\sim100--150150 km s−1^{-1}, even at the AGN positions. We argue that this is a combination of high extinction hiding the turbulent gas, and previous outflows that have cleared the escape paths for their successors.Comment: 15 pages, 17 Figures, accepted for publication in Ap

    Surface Brightness Gradients Produced by the Ring Waves of Star Formation

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    We compute surface brightness profiles of galactic disks for outwardly propagating waves of star formation with a view to investigate the stellar populations in ring galaxies. We consider two mechanisms which can create outwardly propagating star forming rings in a purely gaseous disk --- a self-induced wave and a density wave. We show that the surface brightness profiles produced by both scenarios of ring formation are similar and are strongly sensitive to the velocity of the wave. The results of our computations are compared with the observational quantities sensitive to the young and old stellar populations in the ring galaxies A0035-335 (the Cartwheel galaxy) and VIIZw466. The best fit to the observed radial H_alpha surface brightness distribution in the Cartwheel galaxy is obtained for a wave velocity of about 90 km/s. The red continuum brightness of the ring can be fully explained by the evolving stars present in the trailing part of the wave. However the red continuum brightness in regions internal to the ring indicates that the wave of star formation propagates in a pre-existing stellar disk in the Cartwheel. The H_alpha and K-band surface brightness profiles in VIIZw466 match the values expected from stellar populations produced by a wave of star formation propagating in a purely gaseous disk very well. We conclude that VIIZw466 is probably experiencing the first event of star formation in the disk.Comment: Uses aas2pp4.sty and epsfig.sty, 15 pages To appear in Astrophysical Journal, March 10, 199
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