3 research outputs found
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
First Measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary-Black-hole Merger GW170814
We present a multi-messenger measurement of the Hubble constant H 0 using the binary–black-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s−1 Mpc−1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s−1 Mpc−1, we find {H}_{0 {78}_{-24}^{+96}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1} (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0
TÉTANO NA POPULAÇÃO GERIÁTRICA: PROBLEMÁTICA DA SAÚDE COLETIVA? TÉTANO EN LA POBLACIÓN GERIÁTRICA: PROBLEMÁTICA DE LA SALUD COLECTIVA? TETANUS IN THE GERIATRIC POPULATION: IS THIS A COLLECTIVE HEALTH PROBLEM?
O tétano é uma doença infecciosa, não contagiosa, causada pelo bacilo Clostridium tetani que penetra no organismo através de ferimento. A disfunção psicomotora facilita acidentes entre os idoso e a cobertura vacinal é baixa nesta população contribuindo para letalidade alta. Este estudo tem como objetivo refletir sobre a situação do homem idoso, com relação ao tétano, dentro da perspectiva da Saúde Coletiva. Trata-se de Estudo de Caso realizado com dois pacientes idosos, do sexo masculino, portadores de tétano acidental, internados num hospital do município de Fortaleza. A coleta de dados se deu entre março e abril de 1998. A análise mostra a ausência de cobertura vacinal e da implantação da profilaxia de emergência. Os dois pacientes evoluíram para óbito confirmando alta mortalidade por tétano entre este grupo etário. A reflexão crítica aponta para urgência de abordagem de saúde coletiva.<br>El tétano es una enfermedad infecciosa, no contagiosa, causada por el bacilo Clostridium Tetani que penetra en el organismo a través de una herida. El disturbio psicomotor facilita accidentes entre las personas mayores y la protección por vacunas en esta población es baja, lo que contribuye para un alto índice de mortalidad. Este estudio tiene como objetivo la reflexión sobre la situación del adulto mayor, con relación al tétano, dentro de la perspectiva de la Salud Colectiva. Se trata de un estudio de caso con dos pacientes ancianos, del sexo masculino, portadores del tétano accidental, internados en un hospital del municipio de Fortaleza. La recolección de datos de hizo entre marzo y abril de 1998. El análisis muestra la ausencia de cobertura de la vacuna y de una implementación de profilaxis de emergencia. Los dos pacientes fallecieron, lo que confirma la alta mortalidad por el tétano en este grupo de edad. La reflexión crítica, denota la urgencia de un abordaje desde la salud colectiva.<br>Tetanus is an infectious non-contagious disease caused by the bacillus Clostridium tetani, which penetrates in the organism through wounds. Psychomotor dysfunction facilitates accidents among elderly people and vaccinal coverage is low in this population, thus contributing to high lethality. This study aimed at reflecting on the situation faced by elderly people in relation to tetanus in the perspective of Collective Health. It is a Case Study conducted with two elderly males who had accidental tetanus and were hospitalized in a hospital in the municipality of Fortaleza. Data collection took place from March to April, 1998. The analysis showed the absence of vaccinal coverage as well as of the implementation of emergency prophylaxis. The two patients' conditions developed to death, which confirmed the high mortality due to tetanus in this age group. The critical reflection pointed out the urgency of a collective health approach