The Unbearable Beingness of Light, Dressing and Undressing Photons in Black Hole Spacetimes

Gravitational tidal forces acting on the virtual e+ e- cloud surrounding a photon endow spacetime with a non-trivial refractive index. This has remarkable properties unique to gravitational theories including superluminal low-frequency propagation, in apparent violation of causality, and amplification of the renormalized photon field, in apparent violation of unitarity. Using the geometry of null congruences and the Penrose limit, we illustrate these phenomena and their resolution by tracing the history of a photon as it falls into the near-singularity region of a black hole.Comment: 8 pages, Essay awarded third prize in the Gravity Research Foundation essay competition 201

Signatures of the disk-jet coupling in the Broad-line Radio Quasar 4C+74.26

Here we explore the disk-jet connection in the broad-line radio quasar 4C+74.26, utilizing the results of the multiwavelength monitoring of the source. The target is unique in that its radiative output at radio wavelengths is dominated by a moderately-beamed nuclear jet, at optical frequencies by the accretion disk, and in the hard X-ray range by the disk corona. Our analysis reveals a correlation (local and global significance of 96\% and 98\%, respectively) between the optical and radio bands, with the disk lagging behind the jet by $250 \pm 42$ days. We discuss the possible explanation for this, speculating that the observed disk and the jet flux changes are generated by magnetic fluctuations originating within the innermost parts of a truncated disk, and that the lag is related to a delayed radiative response of the disk when compared with the propagation timescale of magnetic perturbations along relativistic outflow. This scenario is supported by the re-analysis of the NuSTAR data, modelled in terms of a relativistic reflection from the disk illuminated by the coronal emission, which returns the inner disk radius $R_{\rm in}/R_{\rm ISCO} =35^{+40}_{-16}$. We discuss the global energetics in the system, arguing that while the accretion proceeds at the Eddington rate, with the accretion-related bolometric luminosity $L_{\rm bol} \sim 9 \times 10^{46}$ erg s$^{-1}$ $\sim 0.2 L_{\rm Edd}$, the jet total kinetic energy $L_\textrm{j} \sim 4 \times 10^{44}$ erg s$^{-1}$, inferred from the dynamical modelling of the giant radio lobes in the source, constitutes only a small fraction of the available accretion power.Comment: 9 pages and 6 figures, ApJ accepte

Pulsational Mapping of Calcium Across the Surface of a White Dwarf

We constrain the distribution of calcium across the surface of the white dwarf star G29-38 by combining time series spectroscopy from Gemini-North with global time series photometry from the Whole Earth Telescope. G29-38 is actively accreting metals from a known debris disk. Since the metals sink significantly faster than they mix across the surface, any inhomogeneity in the accretion process will appear as an inhomogeneity of the metals on the surface of the star. We measure the flux amplitudes and the calcium equivalent width amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of these amplitudes best fits a model for polar accretion of calcium and rules out equatorial accretion.Comment: Accepted to the Astrophysical Journal. 16 pages, 10 figures

‘Dark Tourism’ and the ‘Kitschification’ of 9/11

This paper aims to interrogate the framing of New York’s Ground Zero as a ‘dark tourist’ destination, with particular reference to the entanglement of notions of kitsch in academic discussions of the events of September 11th 2001. What makes Ground Zero contentious, even scandalous, for many scholars is the presence of a conspicuous commodity culture around the site in the form of tourist souvenirs, leading to accusations of kitschification of memory and the constitution of visitors as ‘tourists of history’. Drawing upon theoretical ideas of Jacques Ranciere, Bruno Latour and W. J. T. Mitchell around image politics, the alignment of kitsch with the figure of the tourist will be questioned, along with the conviction that the so-called ‘teddy-bearification’ of 9/11 threatens the formation of dangerous political subjectivities. In attempting to rid the debates of their default settings, and reliance on essentialist notions of kitsch, it is hoped that that the way will be cleared for the sociological, ethnographic and empirical work necessary to considering the cultural and political significance of the Ground Zero souvenir economy

Migration and access to health care in English medical law: a rhetorical critique

This paper develops a rhetorical critique of recent cases on migration and access to health care in Britain. It argues that the national territory, once a taken-for-granted starting point for reasoning in medical law, has lost its common-sense status as a result of neoliberal globalisation. This is evident in recent decisions involving on the one hand HIV-positive asylum seekers coming to the UK and on the other hand British ‘health tourists’ seeking funding for treatment elsewhere in the European Union. Courts are aware that many of these cases are likely to call forth the sympathy of audiences for the individual concerned, further undermining their privileging of the national scale. In curbing this ‘politics of pity’ they adopt a range of persuasive strategies

Polarization and spectral energy distribution in OJ 287 during the 2016/17 outbursts

We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued to be part of the follow-up flares that exhibited high levels of polarization and originated in the primary black hole jet. We propose that the follow-up flares were induced as a result of accretion disk perturbations, travelling from the site of impact towards the primary SMBH. The timings inferred from our observations allowed us to estimate the propagation speed of these perturbations. Additionally, we make predictions for the future brightness of OJ 287. © 2017 by the authors

The production and consumption activities relating to the celebrity artist

This paper considers the impact of the celebrity artist on the associated production and consumption activities. It also considers the role which entrepreneurial marketing plays in helping to create the celebrity artist aura. The artist Thomas Kinkade is used to illustrate how this occurs in practice. Here, authenticity and nostalgia dimensions are also influential factors. Underpinning these relationships are the roles played out by the media, including communication of celebrity artist identity, and the catalysing of its commodification within the celebrity artist brandscape. An enduring celebrity brand results due to the market creation activities of the celebrity artist. A conceptual model is developed which synthesises the factors behind the production and consumption of the celebrity artist which can stimulate further research. This paper provides innovative insight into the world of the celebrity artist by interrogating the market making and shaping devices behind successful production and consumption practices

Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters

Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole "no-hair theorem" at the 10% level.Peer reviewe