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Freudenthal duality and conformal isometries of extremal black holes
Get PDFWe present a conformal isometry for static extremal black hole solutions in all four-dimensional Einstein-Maxwell-scalar theories with electromagnetic duality groups `of type E_7'. This includes, but is not limited to, all supergravity theories with N>2 supersymmetry and all N=2 supergravity theories with symmetric scalar manifolds. The conformal isometry is valid for arbitrary electromagnetic charge configurations and relies crucially on the notion of Freudenthal duality
A reversible-jump Markov chain Monte Carlo algorithm for 1D inversion of magnetotelluric data
No full textCompact objects and the swampland
Get PDFRecently, two simple criteria were proposed to assess if vacua emerging from an effective scalar field theory are part of the string "landscape" or "swampland". The former are the vacua that emerge from string compactifications; the latter are not obtained by any such compactification and hence may not survive in a UV completed theory of gravity. So far, these criteria have been applied to inflationary and dark energy models. Here we consider them in the context of solitonic compact objects made up of scalar fields: boson stars. Analysing several models (static, rotating, with and without self-interactions), we find that, in this context, the criteria are not independent. Furthermore, we find the universal behaviour that in the region wherein the boson stars are expected to be perturbatively stable, the compact objects may be part of the landscape. By contrast, in the region where they may be faithful black hole mimickers, in the sense they possess a light ring, the criteria fail (are obeyed) for static (rotating) ultracompact boson stars, which should thus be part of the swampland (landscape). We also consider hairy black holes interpolating between these boson stars and the Kerr solution and establish the part of the domain of existence where the swampland criteria are violated. In interpreting these results one should bear in mind, however, that the swampland criteria are not quantitatively strict
Magnetic Monopoles in (Noncommutative) Quantum Mechanics
Get PDFWe utilize the close relation between the complex space C^2 and the real space R^3 to reformulate quantum mechanics in a manner which allows to, either or both, describe magnetic monopoles and quantize the underlying space, obtaining (noncommutative) quantum mechanics (with magnetic monopoles)
Vortices of SO(2) gauged Skyrmions in 2+1 dimensions
Get PDFVortices the SO(2) gauged planar Skyrme model, with a) only Maxwell, b) only Chern-Simons, and c) both Maxwell and Chern-Simons dynamics are studied systematically. In cases a) and b), where both models feature a single parameter λ (the coupling of the potential term), the dependence of the energy on λ is analysed. It is shown that the plots of the energy vs. λ feature discontinuities and branches. In case c), the emphasis is on the evolution of the topological charge, taking non-integer values. Throughout, the properties studied are contrasted with those of the corresponding Abelian Higgs models
Magnetized accretion disks around Kerr black holes with scalar hair - I. Constant angular momentum disks
Get PDFTesting the true nature of black holes - the no-hair hypothesis - will become increasingly more precise in the next few years as new observational data is collected in both the gravitational wave channel and the electromagnetic channel. In this paper we consider numerically generated spacetimes of Kerr black holes with synchronised scalar hair and build stationary models of magnetized thick disks (or tori) around them. Our approach assumes that the disks are not self-gravitating, they obey a polytropic equation of state, the distribution of their specific angular momentum is constant, and they are marginally stable, i.e. the disks completely fill their Roche lobe. Moreover, contrary to existing approaches in the literature, our models are thermodinamically relativist, as the specific enthalpy of the fluid can adopt values significantly larger than unity. We study the dependence of the morphology and properties of the accretion tori on the type of black hole considered, from purely Kerr black holes with varying degrees of spin parameter, namely from a Schwarzschild black hole to a nearly extremal Kerr case, to Kerr black holes with scalar hair with different ADM mass and horizon angular velocity. Comparisons between the disk properties for both types of black holes are presented. The sequences of magnetized, equilibrium disks models discussed in this study can be used as initial data for numerical relativity codes to investigate their dynamical (non-linear) stability and used in tandem with ray-tracing codes to obtain synthetic images of black holes (i.e. shadows) in astrophysically relevant situations where the light source is provided by an emitting accretion disk
Seismic Discrimination between Earthquakes and Quarry Blasts In Ireland
Get PDFThe number of seismic stations operating across Ireland has increased dramatically since 2010. In addition to six
stations operated by the Irish National Seismic Network (INSN), several temporary networks have been deployed
around Ireland. These include the Ireland Array (IA), SIMCRUST, and ISLE networks, operated by the Dublin
Institute for Advanced Studies (DIAS) and the WAVEOBS network, operated jointly by University College Dublin
(UCD) and DIAS. The British Geological Survey (BGS) has been operating a station in Northern Ireland since
2012. As a result, seismic event detection has also increased within this timeframe, with several hundred events
detected per year. However, the vast majority of events (~99%) are believed to be quarry blasts. To avoid
contamination of earthquake catalogs by man-made events, a robust discriminant, or set of discriminants is
necessary. We examine if earthquakes and quarry blasts can be separated at local distances (less than 200km) by
using two waveform-based discriminants. We find that traditional P/S amplitude ratios show very little separation, whereas an S-wave spectral ratio achieves much greater separation between these two types of events
A Local Magnitude Scale for Ireland and its Offshore Regions
Get PDFWe derive a local magnitude scale for Ireland using 104 earthquakes from the period 2010-2017, resulting in 669
amplitude measurements made on stations of the Irish National Seismic Network (INSN), British Geological
Survey (BGS), Ireland Array (IA), ISLE, SIM-CRUST and WAVEOBS networks. The INSN and BGS stations
used in this study are permanent network stations, whereas the remaining networks are temporary deployments.
The local magnitude scale we derive is of the form: ML = log(A) – log(A0) + S, where A is the maximum amplitude
of the earthquake S-wave, log(A0) is a distance dependent correction term accounting for geometrical spreading
and anelastic attenuation, and S is a station correction term. The term log A 0 has the form: -log A 0 = a log R + b R + c, where R is the hypocentral distance. We find that the distance correction log(A0) is very similar to that of
Britain in the distance range 0 < R < 500 km
