Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Predictors for assessing the flowering duration and dynamics of the complex umbellate of fennel in seed production

International audienceFlowering is a critical stage of fennel seed production, which strongly depends on climate factors. In crops such as fennel, the complexity of the umbellate structure and the lack of knowledge about its flowering dynamics make the prediction of the duration of this phenological stage uneasy. In the context of climate change, a reliable predictive tool for the duration of fennel flowering is needed. Our aim was to increase knowledge on fennel flowering dynamics and to propose a model to be used by seed producers. In 2018 and 2019, we studied the development of secondary and tertiary umbels during flowering stage which was determined from the Bundesanstalt Bundessortenamt und Chemische Industrie scale, in plants of four genotypes grown in tunnels. Multiple linear regression (MLR) models were used to select the more accurate equations which consisted of one or more variables as predictors of flowering duration and its dynamics across secondary and tertiary umbels. In all model subsets, the criterion-based procedure was used, followed by a criterion-based hybrid procedure to take advantage of the Mallows' Cp, adjusted R-2 and Bayesian information criterion, for equations and predictor selection. Two variables related to temperature, namely the temperature summation expressed in degree days and the number of days with temperature lower than 15 degrees C, were identified as relevant parameters for predicting flowering duration expressed in days, in secondary as well as tertiary umbels. In addition, the equations and accurate predictors identified for modelling differences in time between flowering starts and ends of secondary and tertiary umbels also highlighted the importance of the number of days when the temperature amplitude is higher than 20 degrees C, the number of days when the mean temperature is higher than 27 degrees C, and the number of days when the relative humidity is higher than 80%