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

Identificación de especies de Naegleria en sitios recreativos en Hornos, Sonora Identification of Naegleria species in recreational areas in Hornos, Sonora

Por medio de técnicas moleculares se han identificado más de 47 especies del género Naegleria, pero en los estudios hechos en México sólo 4 han sido identificadas. El objetivo de este estudio fue identificar el mayor número de Naegleria spp. en sitios recreativos en Hornos, Sonora. Para ésto, se seleccionaron 9 sitios que se muestrearon durante los meses de junio a septiembre de 2004. Se identificaron genéticamente 15 especies aisladas mediante secuenciación de DNA ribosomal, 9 ejemplares como N. lovaniensis, 5 como N. tihangensis y 1 como N. americana. Es la primera vez que se registra la presencia de N. americana y N. tihangensis en la región; esta última especie está muy relacionada con otra amiba patógena, N. australiensis. Una de las cepas aisladas de N. lovaniensis resultó ser única porque difiere en 1 par de bases de las otras cepas de esta especie.<br>By means of molecular techniques more than 47 species of the genus Naegleria have been identified, but in Mexico, only 4 of these species have been so identified. The objective of this study was to identify a higher number of Naegleria spp. in recreational areas in Hornos, Sonora. Nine sites were selected and sampling was performed from June to September of 2004. Fifteen isolated species were identified genetically by means of sequencing ribosomal DNA, 9 specimens as N. lovaniensis, 5 as N. tihangensis and 1 as N. americana. It is the first time that N. americana and N. tihangensis are reported in this region. The latter species is closely related to another pathogenic amoeba, N. australiensis. One of the isolated strains of N. lovaniensis is unique because it differs by 1 bp from the other strains of this species

Multi-messenger Observations of a Binary Neutron Star Merger

International audienceOn 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 $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) 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 $\,{M}_{\odot }$. 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 $\sim 40\,{\rm{Mpc}}$) 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 $\sim 9$ and $\sim 16$ 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 NGC 4993 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