Hairy black holes and the endpoint of AdS4_4 charged superradiance

We construct hairy black hole solutions that merge with the anti-de Sitter (AdS$_4$) Reissner-Nordstr\"om black hole at the onset of superradiance. These hairy black holes have, for a given mass and charge, higher entropy than the corresponding AdS$_4$-Reissner-Nordstr\"om black hole. Therefore, they are natural candidates for the endpoint of the charged superradiant instability. On the other hand, hairy black holes never dominate the canonical and grand-canonical ensembles. The zero-horizon radius of the hairy black holes is a soliton (i.e. a boson star under a gauge transformation). We construct our solutions perturbatively, for small mass and charge, so that the properties of hairy black holes can be used to testify and compare with the endpoint of initial value simulations. We further discuss the near-horizon scalar condensation instability which is also present in global AdS$_4$-Reissner-Nordstr\"om black holes. We highlight the different nature of the near-horizon and superradiant instabilities and that hairy black holes ultimately exist because of the non-linear instability of AdS.Comment: 41 pages, 6 figures. v2: Minor changes to match published versio

Charged black hole bombs in a Minkowski cavity

Press and Teukolsky famously introduced the concept of a black hole bomb system: a scalar field scattering a Kerr black hole confined inside a mirror undergoes superradiant amplification that keeps repeating due to the reflecting boundary conditions at the mirror. A similar charged black hole bomb system exists if we have a charged scalar field propagating in a Reissner-Nordstrom black hole confined inside a box. We point out that scalar fields propagating in such a background are unstable not only to superradiance but also to a mechanism known as the near-horizon scalar condensation instability. The two instabilities are typically entangled but we identify regimes in the phase space where one of them is suppressed but the other is present, and vice-versa (we do this explicitly for the charged but non-rotating black hole bomb). These `corners' in the phase space, together with a numerical study of the instabilities allow us to identify accurately the onset of the instabilities. Our results should thus be useful to make educated choices of initial data for the Cauchy problem that follows the time evolution and endpoint of the instabilities. Finally, we use a simple thermodynamic model (that makes no use of the equations of motion) to find the leading order thermodynamic properties of hairy black holes and solitons that should exist as a consequence (and that should be the endpoint) of these instabilities. In a companion publication, we explicitly solve the Einstein-Maxwell-scalar equations of motion to find the properties of these hairy solutions at higher order in perturbation theory.Comment: 31 pages, 9 Figure

Assessment of the level III of Inoue by preoperative endoscopic ultrasound and elastography: a novel approach to predict a periarterial divestment technique in borderline resectable (BR) or locally advanced (LA) pancreatic adenocarcinoma—How I do it

Pancreatic cancer; Periarterial divestment; Triangle operationCáncer de páncreas; Desinversión periarterial; Operación triangularCàncer de pàncrees; Desinversió periarterial; Operació triangularBackground Periarterial divestment is a surgical technique to approach borderline resectable (BR) or locally advanced (LA) pancreatic ductal adenocarcinoma (PDAC) with arterial involvement. There are no reports in the literature regarding the role of endoscopic ultrasound and elastography (EUS-EG) in exploring the integrity of Inoue’s level III and its correlation with the periarterial divestment technique feasibility. Our research is aimed at exploring the role of EUS-EG in this scenario. Methods We describe our approach to Inoue’s level II by EUS-EG in patients with BR and LA pancreatic cancer patients after neoadjuvant chemotherapy. Results Between June 2019 and December 2020, four patients out of 25 were eligible to perform a preoperative EUS-EG. In all cases, Inoue’s level III integrity was corroborated by EUS-EG and confirmed posteriorly in the surgical scenario where a periarterial divestment technique was feasible. Vein resections were necessary in all cases, with no need for arterial resection. An R0 (> 1 mm) margin was achieved in all patients, and the histopathological assessment showed the presence of neurovascular tissue at the peripheral arterial margin. Conclusion Preoperatively, EUS-EG is a novel approach to explore the integrity of Inoue’s level III and could be helpful to preclude a periarterial divestment technique in borderline resectable or locally advanced pancreatic adenocarcinoma with arterial involvement.Open Access Funding provided by Universitat Autonoma de Barcelona

Hairy black holes, solitons and multi-oscillators

This thesis is centered in the study of new solutions to Einstein’s equations. A common property of all new solutions presented in this thesis is that they have a scalar field condensate, independently of having a horizon or not. A key motivation for studying such cases is given by the gauge/gravity duality hence our starting point will be asymptotically AdS spacetimes. However, we will apply some of the intuition gained from this context to asymptotically flat spacetimes. Within this context, there are two main different parts in this thesis:♦The study of linear instabilities of charged black holes and the construction of the endpoint of the instabilities: hairy black holes. Firstly, one considers the linear problem of scalar field perturbations in order to characterise the unstable region as well as determining the onset of the instability. This onset is given by a zero-mode perturbation, hence it is regular in the past and future horizons. This zero-mode signals the possible existence of a new solution. Secondly, we solve the non-linear problem using a perturbative expansion and encounter two new solutions in the system: a soliton, which is a horizonless solution and a hairy black hole which is the endpoint of the linear instabilities. This study is performed in asymptotically AdS spacetimes and in asymptotically flat spacetimes with a box at a finite distance with Dirichlet boundary conditions for the scalar field: the black hole bomb.♦The study of the nonlinear instability of AdS. We present new results in the charactersation of the islands of stability of AdS. In particular we study the dependence of the nonlinear instability on the commensurability of the frequency spectrum of the theory by introducing a double trace deformation in AdS. We study these islands of stability by determining the region of existence of multi-oscillators. In addition, we use the construction as intuition to postulate the existence in asymptotically flat spacetimes of an infinite-parameter family of solutions that oscillate on any number of non-commensurate frequencies. A particular solution within this infinite-parameter family is the well-known boson star solution which oscillates in one frequency. We construct numerically two-frequency solutions: double-oscillators

Projecte constructiu de la nova EDAR d'Amer T.M. d'Amer

Es tracta d'un projecte constructiu d'una EDAR a la localitat d'Amer, la Selva, Girona. Aquesta actuació està encadrada en el programa del PSARU 2005 i consta com a pendent. L'EDAR està projectada per una població equivalent d'uns 2300 hab-eq. El tractament que es farà de les aigües és d'aireig perllongat, mòdul reactor-decantador biològic i recirculació de fangs. El projecte consta de 5 volums: el primer la memòria, els segon els annexos a la memòria, el tercer els plànols, el quart el Plec de prescripcions tècniques i el cinquè el pressupost

Projecte constructiu de la nova EDAR d'Amer T.M. d'Amer

Es tracta d'un projecte constructiu d'una EDAR a la localitat d'Amer, la Selva, Girona. Aquesta actuació està encadrada en el programa del PSARU 2005 i consta com a pendent. L'EDAR està projectada per una població equivalent d'uns 2300 hab-eq. El tractament que es farà de les aigües és d'aireig perllongat, mòdul reactor-decantador biològic i recirculació de fangs. El projecte consta de 5 volums: el primer la memòria, els segon els annexos a la memòria, el tercer els plànols, el quart el Plec de prescripcions tècniques i el cinquè el pressupost

Projecte constructiu de la nova EDAR d'Amer T.M. d'Amer

Es tracta d'un projecte constructiu d'una EDAR a la localitat d'Amer, la Selva, Girona. Aquesta actuació està encadrada en el programa del PSARU 2005 i consta com a pendent. L'EDAR està projectada per una població equivalent d'uns 2300 hab-eq. El tractament que es farà de les aigües és d'aireig perllongat, mòdul reactor-decantador biològic i recirculació de fangs. El projecte consta de 5 volums: el primer la memòria, els segon els annexos a la memòria, el tercer els plànols, el quart el Plec de prescripcions tècniques i el cinquè el pressupost