52 research outputs found
Spinning compact objects in extreme-mass-ratio inspirals
No full textSince the first landmark observation of gravitational waves (GWs) in 2015, GW astronomy has tremendously impacted fundamental physics and astrophysics. A network of four ground-based detectors (the two LIGOs, Virgo and KAGRA) is now in operation, routinely detecting new events. Future space-based obser- vatories, like the Laser Interferometer Space Antenna (LISA), hold the promise to revolutionize GW astronomy by detecting sources non-observable by current detectors, opening avenues for groundbreaking discoveries. Among the prime targets of LISA are extreme mass ratio inspirals (EMRIs), which are binaries consisting of a stellar-mass compact object slowly inspiraling into a supermassive black hole. These systems are unique probes of astrophysics and fundamental physics. Motivated by their potential, here we study in detail the EMRI dynamics in the presence of a spinning small compact object. The tiny mass-ratio in EMRI binaries allows us to treat the smaller companion as a point particle endowed with mass and spin. The latter are free parameters independent of the internal structure of the infalling compact object. The radiation-reaction forces (known as self-force) and equations of motion are typically modeled with perturbative approaches in the mass ratio. At leading order, the dynamics of the particle is governed by the adiabatic emission of energy and angular momentum in gravitational radiation, causing the secular decay of the orbits. All subleading corrections to this general picture are called post-adiabatic terms. The spin of the small compact object starts affecting the GW phase at the first post-adiabatic order (as does the first-order conservative and second-order dissipative self-force). In this thesis, we focus on the measurability of the smaller companion spin by an EMRI detection with LISA. Using the Teukolsky formalism, we derive the GW fluxes and the adiabatic orbital evolution for a spinning particle in the case of circular, equatorial orbits with (anti-)aligned spins. We provide the spin-induced corrections to GW fluxes (numerically and semi-analytically), along with the corresponding post-adiabatic effects on the GW phase, which are novel results for a Kerr background. Based on the phase difference between the gravitational signal from a spinning and a non-spinning particle, we develop a criterion to determine the minimum value of the spin resolvable by LISA. Our analysis points out that precise, model-independent tests on the nature of the small compact object could be achieved by measuring its intrinsic angular momentum. We also suggest that LISA could test the so-called Kerr bound that limits the maximum spin of a rotating black hole, allowing for theory-agnostic constraints.
We then perform an accurate Fisher-matrix study of the EMRI parameters using Teukolsky waveforms to leading order in an adiabatic expansion on a Kerr background. Our parameter estimation takes into account the motion of the LISA constellation, higher harmonics, and includes the leading correction from the smaller companion spin in the post-adiabatic approximation. We particularly focus on the measurability of the small body spin, showing that, for spin-aligned EMRIs on quasi-circular orbits, it cannot be measured with sufficient accuracy. However, due to correlations, its inclusion in the waveform model can deteriorate the accuracy on the measurements of other parameters by orders of magnitude, unless a physically-motivated prior on the small compact object spin is imposed
Dark radiation and observable gravity waves from string inflation
No full textIn this thesis we work on a model of string inflation called fibre inflation. We investigate whether this inflationary model can predict a tensor-to-scalar-ratio of order 0.01 which might be detectable in the near future. The main constraint comes from the amount of axionic dark radiation produced from the inflaton decay at reheating. Very light axions are a generic feature of 4D string models and behave as extra neutrino species.
We first analyze the inflationary dynamics and derive the predictions for the spectral index and the tensor-to-scalar ratio r as a function of the number of e-foldings under the requirement of generating the correct measured amplitude of the density perturbations. We then focus on reheating. We start by computing the inflaton couplings to all particles in our model: MSSM fields in the visible sector and light axions belonging to the hidden sector.
This computation allows us to derive the dominant inflaton decay channels which are into Higgses, gauge bosons and light axions. In turn, these decay rates lead to a clear prediction for the amount of dark radiation in terms of extra neutrino species of about 0.5-0.6.
These values require approximately 57 e-foldings which can allow for a spectral index almost 1.000 and a tensor-to-scalar-ratio around 0.01 in agreement with Planck observations in the presence of extra dark radiation. We finally point out that, due to the high inflationary scale , the supersymmetry breaking scale turns out to be too high to yield a correct Higgs mass around 125 GeV. This tension can be easily overcome if the visible sector is a simple extension of the MSSM like the NMSSM
Analytic solutions for the motion of spinning particles near spherically symmetric black holes and exotic compact objects
No full textRapidly rotating bodies moving in curved space-time experience the so-called spin-curvature force, which becomes important for the motion of compact objects in gravitational-wave inspirals. As a first approximation, this effect is captured in the motion of a spinning test particle. We solve the equations motion of a spinning particle to leading order in spin in arbitrary static and spherically symmetric space-times in terms of one-dimensional closed-form integrals. This solves the problem and proves its integrability in a wide range of modified gravities and near exotic compact objects. Then, by specializing to the case of bound orbits in Schwarzschild space-time, we demonstrate how to express the solution in the form of Jacobi elliptic functions.The notebooks and machine-readable formulas can be found in the repo https://github.com/VojtechW/Analytical-Solution-Spinning-particle-Spherica
The role of regulation and commitment in the development of telecommunications in Chile
No full textOver six decades, Chile experimented with three regulatory regimes and ownership patterns for its telecommunications sectors, each with radically different investment patterns. Until 1970, Chile relied on private ownership and rate-of-return regulation, but excess demand persisted. In the 1970s, Chile relied on public ownership of two regulated monopolies, but the sector grew even more slowly than before. After 1982, Chile deregulated some market segments, introduced benchmark regulation, and returned to private ownership. The new regulatory regime and privatization doubled the number of lines in service in only four years. The author explains investment behavior as a function of the solutions to two contracting problems: between government and the firm, and between government and interest groups. The author concludes that regulatory rules on pricing, entry, and conflict resolution mechanisms are critical for investing in such asset-specific utilities as telecommunications. More important, the outcome of regulatory reform depends on a match between reform and both the prevailing political and judicial systems and interest group politics. According to the author, Chile satisfactorily resolved the two contracting problems in the 1980's. Chile's new regulations are reasonably efficient and very specific about how tariffs are to be calculated, how entry is to be governed, and how conflicts are to be resolved. The rules are embodied in a law that is relatively difficult to change (because the judicial system is independent). The impetus for reform came from the emergency of a new private entrepreneurial class, whose growth depends on modern telecommunications services.Environmental Economics&Policies,Public Sector Economics&Finance,National Governance,ICT Policy and Strategies,Economic Theory&Research
Extreme Love in the SPA: constraining the tidal deformability of supermassive objects with extreme mass ratio inspirals and semi-analytical, frequency-domain waveforms
No full textWe estimate the accuracy in the measurement of the tidal Love number of a
supermassive compact object through the detection of an extreme mass ratio
inspiral~(EMRI) by the future LISA mission. A nonzero Love number would be a
smoking gun for departures from the classical black hole prediction of General
Relativity. We find that an EMRI detection by LISA could set constraints on the
tidal Love number of a spinning central object with dimensionless spin () which are approximately four (six) orders of magnitude
more stringent than what achievable with current ground-based detectors for
stellar-mass binaries. Our approach is based on the stationary phase
approximation to obtain approximate but accurate semi-analytical EMRI waveforms
in the frequency-domain, which greatly speeds up high-precision
Fisher-information matrix computations. This approach can be easily extended to
several other tests of gravity with EMRIs and to efficiently account for
multiple deviations in the waveform at the same time.Comment: 8 pages + appendices and references; 2 tables and 1 figur
“El ahogado más hermoso del mundo”, de Gabriel García Márquez: un devenir de la lectura, la escritura y lo vivido como hermenéutica transtextual desde la perspectiva de Gérard Genette
No full textThis article considers the reading of Gabriel García Márquez\u27s ‘The Handsomest Drowned Man in the World’ as a transtextual hermeneutic from the perspective of Gerard Genett. This means that the writing of the work is not only a kind of imitation of a previous text to produce a new one, but it is the product of a creative process on the part of the author. Accordingly, this paper relies on three referents for the writing of the story, which together can also contribute to a more comprehensive reading of the symbolic, cultural and poetic universe narrated in the story. These are transtextualities, writing techniques and the author\u27s lived experiences. These elements constitute the body of the text in which idiosyncratic, literary and mythical interpretations are introduced, contrary to the ideological positions referring to the Spanish conquest or the folkloric peculiarities of the local order. This gives an image of Gabriel García Márquez not only as an author, but also as a diachronic reader who writes what he has lived from the reinterpretation of the referents of literature, history and culture. Thus, some critics consider that the author\u27s context, his formation as a human being and writer, bring him closer to his sensibility and provide resources to find possible meanings for his work.En este artículo se plantea la lectura del cuento “El ahogado más hermoso del mundo”, de Gabriel García Márquez (1927-2014), publicado en el año 1972, como una hermenéutica transtextual desde la perspectiva de Gérard Genette. Esto significa que la escritura de la obra no es solamente una especie de imitación de un texto anterior para dar lugar a uno nuevo, sino que es el producto de un proceso creativo por parte del autor, quien pone a dialogar los textos en función de una nueva obra. De acuerdo con esto, este texto se apoya en tres referentes para la escritura del cuento, que, en conjunto, también pueden contribuir a una lectura más comprensiva del universo simbólico, cultural y poético narrado en la historia. Estos son las transtextualidades, las técnicas de escritura y las experiencias vividas por el autor. Estos elementos constituyen el cuerpo del texto, en el que se introducen las interpretaciones idiosincráticas, literarias y míticas, contrarias a las posturas ideológicas referidas a la conquista española o a las peculiaridades folklóricas del orden local. Esto da una imagen de Gabriel García Márquez no solo como autor, sino también como lector diacrónico que escribe lo vivido desde la reinterpretación de los referentes de la literatura, la historia y la cultura. Se considera que el contexto del autor y su formación, tanto como ser humano como escritor, hacen fecunda su sensibilidad y proveen recursos para encontrar posibles sentidos en su obra
Advantages and Challenges of Perforated Monopiles in Deep Water Sites: Comprehensive study of stress concentrations and fatigue loads of monopile foundations in deep water sites
No full textThe potential for developing more efficient offshore wind support structures becomes increasingly critical as the offshore wind sector is faced with challenges such as rising commodity prices and shrinking profit margins. These challenges not only impact the industry’s capacity to meet growing global demand but also hinder efforts to address the imperative challenge of decarbonization. As the offshore wind industry expands, the roles of cost-effectiveness and ongoing research will be pivotal in driving the advancement of offshore wind energy on a global scale.The support structure is responsible for supporting the turbine, transferring loads to the ground, and allowing access for inspection and maintenance purposes. The environmental loads acting on an offshore wind support structure (OWSS) result from a combination of waves, wind speed, turbulence intensity acting on the shape of the turbine components. These loads can be grouped in a scatter diagrams that depict the probability of occurrence of a given wind wave combined condition which is also known as a "sea state". Different sea states lead to significant vibrations and stresses on the foundation, which can cause fatigue and failure over time.The perforated monopile consists of a monopile with holes around the splash zone to reduce frontal area, which reduces hydrodynamic loads on the foundation. Assesing the potential of perforated monopiles in deep waters was based on a comparative study of the loads acting on the monopile by developing a model that considers the structural response of the system to different sea states. FEM studies are essential in identifying potential stress concentrations and their effects on the overall integrity and safety of the structure. Thus, analysis focused on assessing the performance of both a reference monopile and a perforated monopile structural models under both parked and power production conditions, including sea states with 50-year and 1-year return periods. The simulations encompassed 35 distinct sea states and computed maximum stresses at critical locations, including the mudline, perforations, and the splash zone.The study found that the perforated monopile displayed an average reduction of 17% in the maximum stresses found at the mudline compared to the reference monopile. This reduction was attributed to improved flow dynamics facilitated by the perforations. However, the splash zone of the perforated monopile experienced increased stresses around the splash zone of up to a factor of four, attributed to higher overturning moments around the perforated area. Next, the analysis continued with a fatigue life assessment, highlighting sea states that could potentially challenge the structural integrity and longevity of the monopiles over their intended operational lifespan.The study explored alternative solutions, such as varying thickness parameters at high-stress areas and using different materials at the splash zone. Additionally, the possibility of different perforation geometries was considered, although it could impact natural frequencies and cause resonance with loading frequencies.To conclude, the research underscores the importance of a comprehensive assessment of monopile designs in offshore renewable energy structures with a discussion and recommendations for further research on the subject. It emphasizes the need for careful consideration of design choices based on specific environmental conditions at the installation site. The findings contribute valuable insights into optimizing monopile designs for long-term performance and structural reliability in varying sea state conditions during power production scenarios.Offshore and Dredging Engineerin
Benefits and costs of international financial integration : theory and facts
No full textThe author provides a selective review of the recent analytical and empirical literature on the benefits and costs of international financial integration. He discusses the impact of financial openness on consumption, investment, and growth, and the impact of foreign bank entry on the domestic financial system. Consistent with some recent studies, the author argues that financial integration must be carefully prepared and managed to ensure that the benefits outweigh the short-run risks. Prudent macroeconomic management, adequate supervision and prudential regulation of the financial system, greater transparency, and improved capacity to manage risk in the private sector are important requirements for coping with potentially abrupt reversals in pro-cyclical, short-term capital flows. The author adopts a more skeptical view than some assessments in two areas, however. First, only foreign direct investment appears to provide dynamic gains and improved prospects for growth; the evidence on the benefits of other types of capital flows remains weak. Second, empirical research on the net benefits associated with foreign bank penetration is far from conclusive; in particular, the possibility that such penetration may lead to adverse changes in the allocation of credit among domestic firms cannot be dismissed on the basis of the existing evidence.Banks&Banking Reform,Capital Markets and Capital Flows,Fiscal&Monetary Policy,Economic Theory&Research,International Terrorism&Counterterrorism,Economic Theory&Research,Banks&Banking Reform,Macroeconomic Management,Environmental Economics&Policies,Financial Intermediation
Author Correction: Transcript expression-aware annotation improves rare variant interpretation
No full textIn this Article, author Marquis P. Vawter was missing from the Genome Aggregation Database Consortium list. They are associated with the affiliation: ‘Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, CA, USA’, and contributed to the generation of the primary data incorporated into the gnomAD resource. The original Article has been corrected online
Author Correction: Covalent coupling of Spike’s receptor binding domain to a multimeric carrier produces a high immune response against SARS-CoV-2 (Scientific Reports, (2022), 12, 1, (692), 10.1038/s41598-021-03675-0)
No full textThe original version of this Article contained an error in Figure 7 where a preliminary rendition was published. The original Figure 7 and accompanying legend appear below. The original Article has been corrected.Fil: Berguer, Paula Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Blaustein, Matías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Bredeston, Luis María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Craig, Patricio Oliver. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: D'alessio, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biociencias, Biotecnología y Biología Traslacional; ArgentinaFil: Elias, Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Farré, Paola C.. Laboratorio Pablo Cassará S.r.l.; ArgentinaFil: Fernández, Natalia Brenda. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gentili, Hernan Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Gándola, Yamila Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Gasulla, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata; Argentina. Universidad de Buenos Aires; ArgentinaFil: Gudesblat, Gustavo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biociencias, Biotecnología y Biología Traslacional; ArgentinaFil: Herrera, María Gabriela. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ibañez, Lorena Itatí. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Idrovo Hidalgo, Tommy. Universidad de Buenos Aires; ArgentinaFil: Nadra, Alejandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Noseda, Diego Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Pavan, Carlos Humberto. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pavan, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Pignataro, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Roman, Ernesto Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Ruberto, Lucas Adolfo Mauro. Universidad de Buenos Aires; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rubinstein, Natalia. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biociencias, Biotecnología y Biología Traslacional; ArgentinaFil: Sanchez, María Victoria. Universidad Nacional de Cuyo; ArgentinaFil: Santos, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biociencias, Biotecnología y Biología Traslacional; ArgentinaFil: Wetzler, Diana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Zelada, Alicia Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin
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