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

A randomized, open-label, cross-over pilot study investigating metabolic product kinetics of the palatable novel ketone ester, bis-octanoyl (R)-1,3-butanediol, and bis-hexanoyl (R)-1,3-butanediol ingestion in healthy adults

Introduction Bis-octanoyl (R)-1,3-butanediol (BO-BD) is a novel, palatable ketone ester that, when consumed, is hydrolyzed in the gastrointestinal tract into octanoic acid (OCT) and (R)-1,3-butanediol (BDO) which are subsequently metabolized into beta-hydroxybutyrate (BHB). Metabolism of BO-BD is hypothesized to be similar to bis-hexanoyl (R)-1,3-butanediol (BH-BD), apart from release of octanoic acid instead of hexanoic acid (HEX). Methods As part of the safety assessment for BO-BD a randomized, cross-over, open-label study in middle-aged, healthy adults ( n = 12) was undertaken to provide a qualitative comparison of plasma BHB, OCT, HEX and BDO concentrations for 8 h following consumption of 12.5 or 25  g of BO-BD and 12.5  g of BH-BD. Results All study products increased plasma BHB and BDO up to 4 h post-consumption. BH-BD increased HEX, whereas BO-BD increased OCT. All kinetic parameters for BHB and BDO were similar between 12.5  g servings of BH-BD and BO-BD while C max and AUC for OCT were higher following 12. 5  g servings of BO-BD as compared to HEX with 12.5  g of BH-BD. All metabolites returned to baseline by 8 h post-consumption. BHB, BDO and OCT C max and AUC were increased with serving size of BO-BD from 12.5 to 25  g . Sensory acceptability scores of BO-BD were significantly higher than for BH-BD. An in vitro hydrolysis experiment using human blood plasma further confirmed that plasma esterases possess the ability to break down the novel ketone esters into BDO, and OCT or HEX. Discussion The two novel ketone ester molecules exhibit similar metabolic breakdown to BHB and BDO and result in transiently higher concentrations of the plasma fatty acids, OCT and HEX, in vivo. Conclusions Given the similar ketone delivery with greater acceptability, BO-BD may offer a more broadly translatable tool to induce physiologic ketosis than BH-BD