Modeling the gravitational wave signature of neutron star black hole coalescences: PhenomNSBH

Accurate gravitational-wave (GW) signal models exist for black-hole binary (BBH) and neutron-star binary (BNS) systems, which are consistent with all of the published GW observations to date. Detections of a third class of compact-binary systems, neutron-star-black-hole (NSBH) binaries, have not yet been confirmed, but are eagerly awaited in the near future. For NSBH systems, GW models do not exist across the viable parameter space of signals. In this work we present the frequency-domain phenomenological model, PhenomNSBH, for GWs produced by NSBH systems with mass ratios from equal-mass up to 15, spin on the black hole up to a dimensionless spin of $|\chi|=0.5$, and tidal deformabilities ranging from 0 (the BBH limit) to 5000. We extend previous work on a phenomenological amplitude model for NSBH systems to produce an amplitude model that is parameterized by a single tidal deformability parameter. This amplitude model is combined with an analytic phase model describing tidal corrections. The resulting approximant is accurate enough to be used to measure the properties of NSBH systems for signal-to-noise ratios (SNRs) up to 50, and is compared to publicly-available NSBH numerical-relativity simulations and hybrid waveforms constructed from numerical-relativity simulations and tidal inspiral approximants. For most signals observed by second-generation ground-based detectors within this SNR limit, it will be difficult to use the GW signal alone to distinguish single NSBH systems from either BNSs or BBHs, and therefore to unambiguously identify an NSBH system

First higher-multipole model of gravitational waves from spinning and coalescing black-hole binaries

Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipoles (l,m) of the radiation during inspiral, merger and ringdown. We introduce a simple method to include the subdominant multipoles to binary black hole gravitational waveforms, given a frequency-domain model for the dominant multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two. No additional tuning to numerical-relativity simulations is required. We apply a variant of this method to the non-precessing PhenomD model. The result, PhenomHM, constitutes the first higher-multipole model of spinning black-hole binaries, and currently includes the (l,m) = (2,2), (3,3), (4,4), (2,1), (3,2), (4,3) radiative moments. Comparisons with numerical-relativity waveforms demonstrate that PhenomHM is more accurate than dominant-multipole-only models for all binary configurations, and typically improves the measurement of binary properties.Comment: 4 pages, 4 figure

European Investigation Order Directive: What About Defence Rights?

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CHY Formulae and Soft Theorems in N = 4 Super Yang-Mills Theory

PhDThe study of scattering amplitudes in quantum eld theories (QFTs) is equally important for high energy phenomenology and for theoretical understanding of fundamental physics. Over the last 15 years there has been an explosion of new techniques, inspired by Witten's celebrated twistor string theory [1]. The N = 4 super Yang-Mills theory (SYM) provides a playground for applying and extending these methods, heavily constrained by spacetime, internal and hidden symmetries. Recently, Cachazo, He and Yuan proposed an algebraic construction of scattering amplitudes at tree level in various QFTs, based on the solution of certain scattering equations [2]. This formula was later extended to tree-level form factors of Tr(F2 SD) in four dimensional Yang-Mills theory [3]. In this thesis we show how this result may be naturally supersymmetrised, and derived from a dual connected formulation. Moreover, we relate our results to a geometric construction of form factors via the Grassmannian [4]. Finally, we argue that ambitwistor string theory provides a natural way to lift the result to arbitrary dimensions, paving the way for loop-level results. In complementary work, it was shown that the subleading soft behaviour of tree-level amplitudes in gauge theory and gravity is universal [5{7]. This unexpected property is related to extended symmetries of the theory acting at null in nity. Moreover, the hidden structure provides additional information relevant for resummation of physical observables. In this thesis, we extend the known results to one-loop level in N = 4 SYM, arguing that IR divergences introduce anomaly terms through nite order in the regulator. We constrain these terms using dual superconformal symmetry, and derive explicit formulae in the MHV and NMHV sectors. This thesis contains documentation for two Mathematica packages, illustrating the original calculations we have performed.STFC studentship

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

El derecho de defensa del sospechoso en los procesos transnacionales: la necesidad de una defensa dual

According to international treaties and European law, the suspect must be granted assistance by a lawyer throughout the proceedings. It is even more accurate in the European Union, which is intending to create an Area of freedom, security and justice. However, in transnational proceedings, the assistance by a lawyer lacks efficiency. This essay aims to identify the reasons of this lack of efficiency and to suggest solutions to mitigate this issue. It is suggested to establish a dual defense, solution which, nonetheless, encounters difficulties in its implementation.En virtud de los tratados internacionales y del derecho de la Unión Europea, el sospechoso debe contar con la asistencia de letrado en todo el proceso penal. Ello es aún más adecuado en la Unión Europea cuando lo que se pretende es crear un Espacio de libertad, seguridad y justicia. No obstante, en los procesos transnacionales esta asistencia letrada carece de efectividad. El presente artículo busca identificar las causas de esta falta de eficiencia y proponer soluciones para subsanar esta carencia. Se sugiere establecer una defensa dual, solución que encuentra, sin embargo, dificultades en la hora de su implementación