We present results from the first directed search for nontensorial gravitational waves. While general relativity allows for tensorial (plus and cross) modes only, a generic metric theory may, in ...principle, predict waves with up to six different polarizations. This analysis is sensitive to continuous signals of scalar, vector, or tensor polarizations, and does not rely on any specific theory of gravity. After searching data from the first observation run of the advanced LIGO detectors for signals at twice the rotational frequency of 200 known pulsars, we find no evidence of gravitational waves of any polarization. We report the first upper limits for scalar and vector strains, finding values comparable in magnitude to previously published limits for tensor strain. Our results may be translated into constraints on specific alternative theories of gravity.
We present the results of the search for gravitational waves (GWs) associated with γ-ray bursts detected during the first observing run of the Advanced Laser Interferometer Gravitational-Wave ...Observatory (LIGO). We find no evidence of a GW signal for any of the 41 γ-ray bursts for which LIGO data are available with sufficient duration. For all γ-ray bursts, we place lower bounds on the distance to the source using the optimistic assumption that GWs with an energy of were emitted within the - Hz band, and we find a median 90% confidence limit of 71 Mpc at 150 Hz. For the subset of 19 short/hard γ-ray bursts, we place lower bounds on distance with a median 90% confidence limit of 90 Mpc for binary neutron star (BNS) coalescences, and 150 and 139 Mpc for neutron star-black hole coalescences with spins aligned to the orbital angular momentum and in a generic configuration, respectively. These are the highest distance limits ever achieved by GW searches. We also discuss in detail the results of the search for GWs associated with GRB 150906B, an event that was localized by the InterPlanetary Network near the local galaxy NGC 3313, which is at a luminosity distance of Mpc (z = 0.0124). Assuming the γ-ray emission is beamed with a jet half-opening angle , we exclude a BNS and a neutron star-black hole in NGC 3313 as the progenitor of this event with confidence >99%. Further, we exclude such progenitors up to a distance of 102 Mpc and 170 Mpc, respectively.
ABSTRACT
Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains 11 signals from black hole and ...neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced bilby: a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that bilby produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the 11 GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that bilby is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals.
1. Selected health and welfare variables of laying hens from 79 flocks kept in alternative husbandry systems were assessed at the end of lay.
2. Investigations were carried out on 100 hens per flock ...at the slaughter line and recorded as part of a novel scoring system. In addition, post-mortem investigations as well as parasitological examinations were conducted on 10 birds from each flock.
3. Birds with access to free range had better plumage than birds kept in barn systems. Housing in aviaries was associated with a higher prevalence of foot pad lesions and keel bone deformations. In addition, poorer plumage, more and worse skin and foot pad lesions were documented in hens slaughtered during the winter months.
4. Oophoritis and/or salpingitis were the most prevalent pathomorphological changes observed. Intestinal parasites, especially Heterakis gallinarum and Ascaridia galli, were frequent. Hens kept indoors had fewer nematoda and cestoda than those from conventional and organic free range.
5. The slaughterhouse protocol allowed direct comparison of variables between flocks and specific problems to be identified in particular flocks. The results could be used to initiate detailed investigations into problematic issues on selected farms.
We report on a new behavior found in numerical simulations of spherically
symmetric gravitational collapse in self-gravitating SU(2) sigma models at
intermediate gravitational coupling constants: The ...critical solution (between
black hole formation and dispersion) closely approximates the continuously
self-similar (CSS) solution for a finite time interval, then departs from this,
and then returns to CSS again. This cycle repeats several times, each with a
different CSS accumulation point. We have preliminary evidence that this same
critical solution is also discretely self-similar (DSS) between the CSS
episodes, but with an echoing period $\Delta$ which varies during the
evolution.
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