Modelling the high mass accretion rate spectra of GX 339-4: Black hole spin from reflection?

We extract all the XMM-Newton EPIC pn burst mode spectra of GX 339-4, together with simultaneous/contemporaneous RXTE data. These include three disc dominated and two soft intermediate spectra, and the combination of broad bandpass/moderate spectral resolution gives some of the best data on these bright soft states in black hole binaries. The disc dominated spectra span a factor three in luminosity, and all show that the disc emission is broader than the simplest multicolour disc model. This is consistent with the expected relativistic smearing and changing colour temperature correction produced by atomic features in the newest disc models. However, these models do not match the data at the 5 per cent level as the predicted atomic features are not present in the data, perhaps indicating that irradiation is important even when the high energy tail is weak. Whatever the reason, this means that the data have smaller errors than the best physical disc models, forcing use of more phenomenological models for the disc emission. We use these for the soft intermediate state data, where previous analysis using a simple disc continuum found an extremely broad residual, identified as the red wing of the iron line from reflection around a highly spinning black hole. However, the iron line energy is close to where the disc and tail have equal fluxes, so using a broader disc continuum changes the residual 'iron line' profile dramatically. With a broader disc continuum model, the inferred line is formed outside of 30 ${\rm{R_g}}$, so cannot constrain black hole spin. We caution that a robust determination of black hole spin from the iron line profile is very difficult where the disc makes a significant contribution at the iron line energy i.e. in most bright black hole states.Comment: 12 pages, 16 figures, published in MNRA

Topics on bar and bulge formation and evolution

I discuss results from the COSMOS survey, showing that the fraction of disc galaxies that is barred decreases considerably with look-back time from z ~ 0.2 to z ~ 0.8. This decrease is more important for small mass and low luminosity spirals. Classical bar formation theory provides a promising framework for understanding these results. I also discuss the formation of discy bulges using N-body simulations reproducing well the properties of observed discy bulges. Thus, these simulated discy bulges have the shape of a disc, they have Sersic profiles with small values of the shape index and their size is of the order of a kpc. They are formed by radial inflow of material driven by the bar and are thus composed of both gas and stars and have a considerable fraction of young stars. They can harbour spiral structure, or an inner bar.Comment: 4 pages, 2 figures, contributed paper to the Rome meeting on "Formation and Evolution of Galaxy Disks", eds, J. Funes, S.J. and E.M. Corsin

Formation and long-term evolution of 3D vortices in protoplanetary discs

In the context of planet formation, anticyclonic vortices have recently received lots of attention for the role they can play in planetesimals formation. Radial migration of intermediate size solids toward the central star may prevent their growth to larger solid grains. On the other hand, vortices can trap the dust and accelerate this growth, counteracting fast radial transport. Multiple effects have been shown to affect this scenario, such as vortex migration or decay. The aim of this paper is to study the formation of vortices by the Rossby wave instability and their long term evolution in a full three dimensional protoplanetary disc. We use a robust numerical scheme combined with adaptive mesh refinement in cylindrical coordinates, allowing to affordably compute long term 3D evolutions. We consider a full disc stratified both radially and vertically that is prone to formation of vortices by the Rossby wave instability. We show that the 3D Rossby vortices grow and survive over hundreds of years without migration. The localized overdensity which initiated the instability and vortex formation survives the growth of the Rossby wave instability for very long times. When the vortices are no longer sustained by the Rossby wave instability, their shape changes toward more elliptical vortices. This allows them to survive shear-driven destruction, but they may be prone to elliptical instability and slow decay. When the conditions for growing Rossby wave-related instabilities are maintained in the disc, large-scale vortices can survive over very long timescales and may be able to concentrate solids.Comment: Accepted for publication in A&

Jan Snyman papers

Biographical history and context: Professor Jan Snyman spent most of his life researching the lesser known and marginalised San languages of Botswana and South West Africa (now Namibia). Together with O. Kohler, E. Westphal and A. Traill, he pioneered linguistic studies on these endangered languages of Africa. He contributed significantly in collection of the data that helped classify and understand the grammar of San languages. Snyman also wrote several grammars in the form of monographs and notes on these languages. By the time he died, in 2002, a draft for the Tshwaa and Kua languages had been completed. Content: Linguistic, phonetics and orthography research materials including fonts for phonetic languages. Covering dates: 1967-200

Eat what you hear: Gustasonic discourses and the material culture of commercial sound recording

This article analyzes discursive linkages between acts of listening and eating within a combined multisensory regime that the authors label the gustasonic. Including both marketing discourses mobilized by the commercial music industry and representations of record consumption in popular media texts, gustasonic discourses have shaped forms and experiences of recorded sound culture from the gramophone era to the present. The authors examine three prominent modalities of gustasonic discourse: (1) discourses that position records as edible objects for physical ingestion; (2) discourses that preserve linkages between listening and eating but incorporate musical recordings into the packaging of other foodstuffs; and (3) discourses of gustasonic distinction that position the listener as someone with discriminating taste. While the gustasonic on one hand serves as an aid to consumerism, it can also cultivate a countervailing collecting impulse that resists music’s commodity status and inscribes sound recording within alternative systems of culture value

Evolution of transonicity in an accretion disc

For inviscid, rotational accretion flows driven by a general pseudo-Newtonian potential on to a Schwarzschild black hole, the only possible fixed points are saddle points and centre-type points. For the specific choice of the Newtonian potential, the flow has only two critical points, of which the outer one is a saddle point while the inner one is a centre-type point. A restrictive upper bound is imposed on the admissible range of values of the angular momentum of sub-Keplerian flows through a saddle point. These flows are very unstable to any deviation from a necessarily precise boundary condition. The difficulties against the physical realisability of a solution passing through the saddle point have been addressed through a temporal evolution of the flow, which gives a non-perturbative mechanism for selecting a transonic solution passing through the saddle point. An equation of motion for a real-time perturbation about the stationary flows reveals a very close correspondence with the metric of an acoustic black hole, which is also an indication of the primacy of transonicity.Comment: 18 page

Diversity of Zoanthids (Anthozoa: Hexacorallia) on Hawaiian Seamounts: Description of the Hawaiian Gold Coral and Additional Zoanthids

The Hawaiian gold coral has a history of exploitation from the deep slopes and seamounts of the Hawaiian Islands as one of the precious corals commercialised in the jewellery industry. Due to its peculiar characteristic of building a scleroproteic skeleton, this zoanthid has been referred as Gerardia sp. (a junior synonym of Savalia Nardo, 1844) but never formally described or examined by taxonomists despite its commercial interest. While collection of Hawaiian gold coral is now regulated, globally seamounts habitats are increasingly threatened by a variety of anthropogenic impacts. However, impact assessment studies and conservation measures cannot be taken without consistent knowledge of the biodiversity of such environments. Recently, multiple samples of octocoral-associated zoanthids were collected from the deep slopes of the islands and seamounts of the Hawaiian Archipelago. The molecular and morphological examination of these zoanthids revealed the presence of at least five different species including the gold coral. Among these only the gold coral appeared to create its own skeleton, two other species are simply using the octocoral as substrate, and the situation is not clear for the final two species. Phylogenetically, all these species appear related to zoanthids of the genus Savalia as well as to the octocoral-associated zoanthid Corallizoanthus tsukaharai, suggesting a common ancestor to all octocoral-associated zoanthids. The diversity of zoanthids described or observed during this study is comparable to levels of diversity found in shallow water tropical coral reefs. Such unexpected species diversity is symptomatic of the lack of biological exploration and taxonomic studies of the diversity of seamount hexacorals

Orthopaedic surgery

Over the past fifty years orthopaedic surgery made giant strides forward. It developed from a discipline that dealt primarily with the treatment of fractures, bone infections and tendon transfers and that treated degenerate joints by fusing them to one of such sophistication as to be able to treat fractures by internal fixation and early mobilisation. It is now possible to replace most joints in the body and to benefit from the results of stem cell research that hold promise of yet further exciting developments, the more important but by no means exclusive advances in orthopaedic surgery are presented.peer-reviewe