Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO’s second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h95%0=3.47×10−25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering

First Measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary-Black-hole Merger GW170814

We present a multi-messenger measurement of the Hubble constant H 0 using the binary–black-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in ${H}_{0}={75}_{-32}^{+40}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$, which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s−1 Mpc−1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s−1 Mpc−1, we find {H}_{0 {78}_{-24}^{+96}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1} (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0

SYNTHESIS OF 7-SUBSTITUTED 3-beta-D-RIBOFURANOSYL-3H-IMIDAZO[2,1-i]PURINES

A method for the synthesis of 7-substituted 3-beta-D-ribofuranosyl-3H-imidazo[2,1-i]purines has been devised whereby compounds were prepared in a few steps from a common intermediate, 3-(2',3'-O-isopropylidene-beta-D-ribofuranosyl)-3H-imidazo[2,1-i]purine-7-carbaldehyde, obtained from the reaction of 2',3'-O-isopropylideneadenosine with bromomalonaldehyde. The formyl group of the carbaldehyde was subsequently reductively aminated and the resulting secondary amines were then further derivatized either by acylation, lactamization or reductive alkylation

Halogenated terpenoids. XXVII. Dibromo epoxy derivatives of (R)-()-limonene

Six dibromo epoxides related to limonene are reported. The synthesis and separation of these isomers allows an improved synthesis of the pure diastereomeric 8, 9-epoxides of limonene

Modeling NMR parameters by DFT methods as an aid to the conformational analysis of cis-fused 7a(8a)-methyl octa(hexa)hydrocyclopenta[d][1,3]oxazines and [3,1]benzoxazines

The energies of the preferred conformations of four 7a-methyl octa(or hexa)hydrocyclopenta[d][1,3]-oxazines, five 8a-methyl octa(or hexa)hydro[3,1]benzoxazines, and 8a-methyl hexahydro[1,3]benzoxazinone, all cis-fused, were investigated by DFT methods. Following geometry optimization at the B3LYP/6-31 G(d,p) level, both the proton chemical shifts and the vicinal coupling constants between H-4a and the H-4 and H-5 protons were calculated at the B3LYP/cc-pVTZ level and compared to the previously experimentally measured values. The agreement between the calculated and the experimental chemical shifts was found to be good. Similarly, the agreement between the calculated and the experimental vicinal coupling constants was also found to be good, thus providing a methodology for determining the conformational equilibria of such systems that is comparable in many respects to experimental approaches such as variable-temperature NMR or to the use of model coupling constant values, when available, from analogous compounds