Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams

Southern African Large Telescope Spectroscopy of BL Lacs for the CTA project

In the last two decades, very-high-energy gamma-ray astronomy has reached maturity: over 200 sources have been detected, both Galactic and extragalactic, by ground-based experiments. At present, Active Galactic Nuclei (AGN) make up about 40% of the more than 200 sources detected at very high energies with ground-based telescopes, the majority of which are blazars, i.e. their jets are closely aligned with the line of sight to Earth and three quarters of which are classified as high-frequency peaked BL Lac objects. One challenge to studies of the cosmological evolution of BL Lacs is the difficulty of obtaining redshifts from their nearly featureless, continuum-dominated spectra. It is expected that a significant fraction of the AGN to be detected with the future Cherenkov Telescope Array (CTA) observatory will have no spectroscopic redshifts, compromising the reliability of BL Lac population studies, particularly of their cosmic evolution. We started an effort in 2019 to measure the redshifts of a large fraction of the AGN that are likely to be detected with CTA, using the Southern African Large Telescope (SALT). In this contribution, we present two results from an on-going SALT program focused on the determination of BL Lac object redshifts that will be relevant for the CTA observatory

Problema científico, población y muestra. Revisión de conceptos y ejemplo

La investigación científica es reconocida como la manera más directa y eficiente de obtener conocimientos científicos pero la universalización que alcanza hoy en nuestro país puede producir la falsa impresión de que ya no se trata de una actividad de la más alta complejidad y que ya no persigue obtener conocimiento generalizable. Se trata aquí sobre el planteamiento del problema científico y las definiciones de población y muestra, dos aspectos que son parte vital de la planificación de una investigación y que a menudo resultan confundidos o mal planteados en las diferentes formas de reporte de resultados de una investigación. Se recorre el concepto de problema científico y los elementos que integran su planteamiento: su expresión a través de preguntas e hipótesis; la descripción del marco teórico y práctico donde se inserta y la justificación de la necesidad de encararlo. Se abordan además los conceptos de población y muestra y su relación con el problema científico. Se profundiza en la idea de que la población en una investigación no es más que la delimitación del conjunto de personas en el cual deben ser válidas las conclusiones relativas al problema científico que le da origen y se plantea que la población, más que delimitada por espacio y tiempo, deberá limitarse por las características específicas que definen al ser humano al cual se refiere el problema científico en cuestión. La muestra es la parte de la población que se estudia y brinda la información que permitirá responder a las preguntas y dar fin a la investigación. Se concluye que siempre deberá hacerse una distinción entre la población o dominio sobre el que se hace la pregunta que conforma el problema de investigación y la muestra o grupo de unidades donde se hacen las observaciones. Lo abordado se ilustra con dos ejemplos del área de la Cardiología

Problema científico, población y muestra. Revisión de conceptos y ejemplo

La investigación científica es reconocida como la manera más directa y eficiente de obtener conocimientos científicos pero la universalización que alcanza hoy en nuestro país puede producir la falsa impresión de que ya no se trata de una actividad de la más alta complejidad y que ya no persigue obtener conocimiento generalizable. Se trata aquí sobre el planteamiento del problema científico y las definiciones de población y muestra, dos aspectos que son parte vital de la planificación de una investigación y que a menudo resultan confundidos o mal planteados en las diferentes formas de reporte de resultados de una investigación. Se recorre el concepto de problema científico y los elementos que integran su planteamiento: su expresión a través de preguntas e hipótesis; la descripción del marco teórico y práctico donde se inserta y la justificación de la necesidad de encararlo. Se abordan además los conceptos de población y muestra y su relación con el problema científico. Se profundiza en la idea de que la población en una investigación no es más que la delimitación del conjunto de personas en el cual deben ser válidas las conclusiones relativas al problema científico que le da origen y se plantea que la población, más que delimitada por espacio y tiempo, deberá limitarse por las características específicas que definen al ser humano al cual se refiere el problema científico en cuestión. La muestra es la parte de la población que se estudia y brinda la información que permitirá responder a las preguntas y dar fin a la investigación. Se concluye que siempre deberá hacerse una distinción entre la población o dominio sobre el que se hace la pregunta que conforma el problema de investigación y la muestra o grupo de unidades donde se hacen las observaciones. Lo abordado se ilustra con dos ejemplos del área de la Cardiología

Análisis de decisión: Coste-efectividad en el tratamiento quirúrgico de la neuralgia del trigémino

Introduction: Trigeminal neuralgia is a facial pain syndrome known and characterized by severe, intermittent, electric shock-like, shooting pain in the face for which a number of surgical therapies have been used. To date no ideal, minimally invasive, patient-acceptable treatment is available, hence both patients and specialists face substantial uncertainty when making decisions regarding therapeutic action. Objective: To identify which surgical treatment for TN offers the best opportunity in terms of cost-effectiveness. Material and method: A study was performed using a decision analysis/cost-effectiveness analysis design considering five surgical alternatives in the management of TN: radiofrequency thermocoagulation, glycerol microcompression, balloon microcompression, radiosurgery, and microvascular decompression. Data were obtained from the literature. A review was carried out of the MEDLINE database from 2000 to 2010 via PubMed Central. Studies were selected that addressed primary trigeminal neuralgia and demonstrated pain relief and reduced mortality and complication rates. In all 196 studies were identified but only 22 (11.22 %) were eligible for the study. The software package used was the DATA 3.5 for Health Care, version 3.5.5, program by TreeAge Software Inc. Results: Microvascular decompression and thermocoagulation are the techniques more likely to provide effective pain relief, with expected values of 0.8946 and 0.8863, respectively. For the relationship between cost and outcome pain-free days were considered; the best choice in terms of cost-effectiveness is surgery and thermocoagulation, with a lower value in the marginal cost-effectiveness ratio: $171.58 for an effectiveness of 89$171.58 para una efectividad de la cirugía de 89 % por cada paciente tratado. Conclusión: Considerando que la termocoagulación por radiofrecuencia y la microdescompresión vascular constituyen las variantes quirúrgicas más utilizadas por la alta efectividad, concluimos que la termocoagulación por radiofrecuencia es más beneficiosa, ofrece escasas complicaciones y es menos costosa

Avaliação prognóstica em pacientes com doença cardíaca isquêmica tratado com a CRM

Introduction: Ischemic heart disease is among the major death causes in Cuba and also at world level; the coronary surgery is one of the pillar of its treatment.Objective: To identify the indicator of adverse cardiac events and survival in patients treated by surgery of myocardial revascularization.Method: A cohort longitudinal prospective study was conducted in the service of Cardiovascular Surgery of Cardiocenter of the "Hermanos Ameijeiras" Clinical Surgical Hospital from March, 2012 to March, 2013. The study universe included the total or patients presenting with ischemic heart disease and with criterion of myocardial revascularization by coronary surgery. The sample included 178 consecutive patients fulfilling the inclusion criteria. The variables response analyzed were: death by cardiac cause, non-fatal infarct, revascularization of target vessel, cerebrovascular accident, readmission, cardiac failure and major adverse event combined.Results: The surgery with heartbeating was associated with a great incidence of adverse events, although not in a significantly. The anthropometric variables (abdominal circumference and waist/hip index) were associated in a significant way with the variables of response (p: 0.018 and p: 0.007, respectively). The patients having a low output, malignant arrhythmias and perioperative ischemia were associated with significantly with deat, non-fatal infarct and the need of revascularization of target vessel ( (Chi2 = 9,392 , p = 0,002).Conclusions: The indicators variables of adverse cardiac events and survival in patients treated by myocardial revascularization are: the support used in surgery, anthropometric variables and complications in the immediate postoperative period.Introducción: La cardiopatía isquémica está entre las principales causas de muerte en Cuba y a nivel mundial; la cirugía coronaria constituye uno de los pilares de su tratamiento.Objetivo: Identificar las variables predictoras de eventos cardíacos adversos y de sobrevida en los pacientes tratados mediante cirugía de revascularización miocárdica.Método: Se realizó un estudio de cohorte longitudinal prospectivo en el servicio de Cirugía Cardiovascular del Cardiocentro del Hospital clínico quirúrgico “Hermanos Ameijeiras”, desde marzo del 2012 hasta marzo del 2013. El universo o población objeto de estudio, estuvo integrado por la totalidad de pacientes con cardiopatía isquémica y con criterio de revascularización miocárdica mediante cirugía coronaria. La muestra se constituyó por 178 pacientes consecutivos que cumplieron con los criterios de inclusión. Las variables de respuesta analizadas fueron: muerte de causa cardiaca, infarto no fatal, revascularización del vaso diana, accidente cerebrovascular, reingreso, insuficiencia cardiaca y eventos adversos mayores combinados.Resultados: La cirugía con corazón latiendo se asoció a mayor incidencia de los eventos adversos, aunque no de manera significativa. Las variables antropométricas (circunferencia abdominal e índice cintura/cadera) se asociaron de forma significativa a las variables de respuesta (p: 0.018 y p: 0.007 respectivamente). Los pacientes que presentaron bajo gasto, arritmias malignas e isquemia perioperatoria se asociaron de manera significativa a la muerte, infarto no fatal y necesidad de revascularización del vaso diana (Chi cuadrado= 9,392  p = 0,002).Conclusiones: las variables predictoras de eventos cardíacos adversos y de sobrevida en los pacientes tratados mediante cirugía de revascularización miocárdica son: el soporte empleado en la cirugía, las variables antropométricas y las complicaciones en el posoperatorio inmediato.Introduction: La cardiopathie ischémique est parmi les principales causes de décès à Cuba et dans le monde; PAC est l'une des pierres angulaires du traitement.Objectif: identifier les prédicteurs d'événements cardiaques indésirables et la survie chez les patients traités avec un pontage coronarien.Méthode: Un service de cohorte longitudinale Chirurgie cardiovasculaire Cardiologie prospective chirurgicale Hôpital clinique "Hermanos Ameijeiras" a été menée à partir de Mars 2012 Mars 2013. L'univers ou de la population à l'étude était composée de tous les patients atteints de cardiopathie ischémique et de critères de revascularisation myocardique par la chirurgie coronarienne. L'échantillon était composé de 178 patients consécutifs qui remplissaient les critères d'inclusion. Les variables de réponse analysés étaient la mort cardiaque, infarctus du myocarde, revascularisation du vaisseau cible, accident vasculaire cérébral, la réadmission, l'insuffisance cardiaque et événements adverses majeurs combinés.Résultats: La chirurgie de cœur battant est associée à une incidence plus élevée d'événements indésirables, mais pas de manière significative. Variables anthropométriques (indice de la circonférence abdominale et la taille / hanche) ont été associés de façon significative aux variables de réponse (p = 0,018 et p: 0,007 respectivement). Les patients ayant présenté une faible sortie, arythmie maligne et l'ischémie périopératoire étaient significativement associés les circonstances du décès, infarctus du myocarde et la nécessité de revascularisation du vaisseau cible (Chi carré = 9,392 p = 0,002).Conclusions: prédicteurs d'événements cardiaques indésirables et la survie chez les patients traités avec un pontage coronarien sont le support utilisé en chirurgie, variables anthropométriques et des complications dans la période postopératoire immédiate.Introdução: A doença isquêmica do coração está entre as principais causas de morte em Cuba e no mundo; Revascularização do miocárdio é uma das pedras angulares do tratamento.Objetivo: Identificar preditores de eventos cardíacos adversos e sobrevida em pacientes tratados com revascularização do miocárdio.Método: Um estudo prospectivo de coorte longitudinal serviço de Cirurgia Cardiovascular Cardiologia Clínica Cirúrgica Hospital "Hermanos Ameijeiras" foi realizado de março de 2012 a março de 2013. O universo ou a população em estudo consistiu de todos pacientes com doença isquêmica do coração e critérios de revascularização miocárdica por cirurgia coronariana. A amostra foi composta de 178 pacientes consecutivos que preencheram os critérios de inclusão. As variáveis resposta analisadas foram morte cardíaca, infarto do miocárdio não fatal, revascularização do vaso-alvo, acidente vascular cerebral, a readmissão, insuficiência cardíaca e eventos adversos maiores combinados.Resultados: A cirurgia de coração a bater está associada com uma maior incidência de eventos adversos, mas não de forma significativa. As variáveis antropométricas (índice de circunferência abdominal e relação cintura / quadril) foram associados de forma significativa para as variáveis de resposta (p = 0,018 e p: 0,007 respectivamente). Os doentes que apresentaram baixo débito, arritmia maligna e isquemia peri-operatória foram associados significativamente maneira da morte, infarto do miocárdio não fatal e necessidade de revascularização do vaso alvo (Chi quadrado = 9,392 p = 0,002).Conclusões: preditores de eventos cardíacos adversos e sobrevida em pacientes tratados com revascularização do miocárdio são o suporte utilizado na cirurgia, variáveis antropométricas e complicações no pós-operatório imediato

Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy γ rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different γ-ray instruments

Introducing the CTA concept

The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project

CTA contributions to the 33rd International Cosmic Ray Conference (ICRC2013)

Compilation of CTA contributions to the proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), which took place in 2-9 July, 2013, in Rio de Janeiro, BrazilComment: Index of CTA conference proceedings at the ICRC2013, Rio de Janeiro (Brazil). v1: placeholder with no arXiv links yet, to be replaced once individual contributions have been all submitted. v2: final with arXiv links to all CTA contributions and full author lis