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

Synthesis and characterization of a stable paramagnetic hexacoordinated oxochromium(IV) complex with dianionic tetradentate schiff base ligand salen

A paramagnetic octahedral oxochromium(IV) complex with dianionic tetradentate ligand salen (where H2salen is N,N'-bis(salicylidene)-1,2-ethylenediamine) has been synthesized. This compound [CrO(OH2)(salen)] (1) is characterized by elemental analysis, magnetic moment measurement, IR, UV-Vis and EPR spectroscopic studies. Measured room temperature (RT) magnetic moment value is 2.96 BM for 1 indicates a d2 system with a triplet ground state. The magnetic moment value rules out a large spin-orbit coupling. The RT and LNT powder EPR spectra of 1 in X-band clearly shows two lines, one around g = 1.965 and the other with larger intensity at g = 4.26 ± 0.10. The first line at g = 1.965 corresponds to the |0> ↔ |± 1> transition from the Kramers doublet |± 1>, while the broad and intense line at low field with the g-value of 4.26 ± 0.10 is due to the forbidden transition |-1> ↔ |+1>. Compound 1 displays two successive reductions at -0.76 and -1.63 V (versus Ag/AgCl), respectively, while it undergoes only one irreversible oxidation as evident from the well-defined anodic wave at +1.48 V in its cyclic voltammogram

Synthesis and characterization of two stable paramagnetic octahedral chromium(IV) complexes with dianionic tridentate SNO donor ligands and of a chromium(III) complex with a ONO donor ligand

Two novel paramagnetic octahedral chromium(IV) complexes with dianionic tridentate SNO donor ligands containing extended p-system have been synthesized while only a paramagnetic octahedral chromium(III) complex is obtained when a related dianionic tridentate ONO donor ligand is used under similar conditions. These bischelate complexes [Cr(abtsal)2] (1) (abtsalH2 is the Schiff base of o-aminobenzenethiol and salicylaldehyde), [Cr(4-PhTSCsal)2] · H2O (2) (4-PhTSCsalH2 is the Schiff base of 4-phenylthiosemicarbazide and salicylaldehyde) and K[Cr(sap)2]· H2O (3) (sapH2 is the tridentate Schiff base of salicylaldehyde and o-aminophenol) are characterized by elemental analyses, magnetic moment measurements, IR, UV-Vis and EPR spectroscopic studies. Compound 3 has been structurally characterized by X-ray crystallography. Measured room temperature (RT) magnetic moment values are 2.98 BM for 1 and 2.83 BM for 2 indicating a d2 system with a triplet ground state in both the cases. On the other hand, the magnetic moment value for 3 is found to be 3.74 BM at RT and is consistent with the presence of three unpaired electrons for a d3 Cr(III) ion. The magnetic moment values rule out the large spin-orbit coupling which is substantiated by the presence of RT EPR signals. Compounds 1 and 2 exhibit very similar powder EPR spectra at RT and LNT, which show the allowed transition ΔMs = ±1 (g = 2.004 for both 1 and 2) as well as the "forbidden" half-field transition (ΔMs = ±2) at g = 4.105 for 1 and g = 4.318 for 2, respectively. The X-band LNT frozen glass EPR spectrum of 1 in DMF shows the presence of zero-field split rhombic symmetry character, and results in the parameters g 2.0, D = 740 G, and E = 260 G. It suggests that the intensity ofΔMs = ±2 forbidden transition is large due to the large D value. The X-band frozen glass EPR spectrum of compound 3 in DMF is found to be very similar to that reported for trans-[Cr(py)4F2]+ in DMF-H2O-MeOH glass. The large difference (~700 mV) in the reduction potential for the two octahedral complexes 1 (-1.40 V) and 3 (-0.70 V) is attributed to the difference in their metal ion oxidation states

Reduction of carboxylato-bound chromium(IV) with hydroxylamine

827-830Aqueous chromium(IV), stabilized through ligation by 2-ethyl-2-hydroxybutanoate ion, undergo facile reduction with hydroxylamine. Cr(IV) forms a precursor complex with NH30H+ (Kc = 30 ± 7 M-1) and electron is transferred from NH3OH+ to Cr(IV) within this complex. This electron transfer process is inhibited by excess ligand anion, as well as by hydrogen ion

Ligational Behaviour of a Tridentate NNS Donor Ligand towards Salts of Co(III), Ni(II) & Cu(II)

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Chemistry of molybdenum with hard-soft donor ligands. 2. Molybdenum(VI), -(V), and -(IV) oxo complexes with tridentate schiff base ligands

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