On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

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GW170817: observation of gravitational waves from a binary neutron star inspiral

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

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The Observation of Gravitational Waves from a Binary Black Hole Merger

We present the results from three gravitational-wave searches for coalescing compact binaries with component masses above 1 Ma™ during the first and second observing runs of the advanced gravitational-wave detector network. During the first observing run (O1), from September 12, 2015 to January 19, 2016, gravitational waves from three binary black hole mergers were detected. The second observing run (O2), which ran from November 30, 2016 to August 25, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole mergers, four of which we report here for the first time: GW170729, GW170809, GW170818, and GW170823. For all significant gravitational-wave events, we provide estimates of the source properties. The detected binary black holes have total masses between 18.6-0.7+3.2 Mâ™ and 84.4-11.1+15.8 Mâ™ and range in distance between 320-110+120 and 2840-1360+1400 Mpc. No neutron star-black hole mergers were detected. In addition to highly significant gravitational-wave events, we also provide a list of marginal event candidates with an estimated false-alarm rate less than 1 per 30 days. From these results over the first two observing runs, which include approximately one gravitational-wave detection per 15 days of data searched, we infer merger rates at the 90% confidence intervals of 110-3840 Gpc-3 y-1 for binary neutron stars and 9.7-101 Gpc-3 y-1 for binary black holes assuming fixed population distributions and determine a neutron star-black hole merger rate 90% upper limit of 610 Gpc-3 y-1.

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GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs

Elements Of X Ray Diffraction

We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Hydrolysis of phosphate ester (Mono-N-ethyl-o-toluidine phosphate) in the presence of different surfactants has been studied at 303 K. The rate of reaction has been found to be first-order and fractional order kinetics with respect to [substrate] and [HCl] respectively. The cationic micelles of cetyltrimethylammonium bromide (CTAB), anionic micelles of sodium dodecyl sulfate (SDS) and nonionic micelles of Brij-35 enhanced the rate of reaction to a maximum value and thereafter, the increase in concentration of surfactant decreased the reaction rate. The rate of reaction increased with increase of dielectric constant of the medium. The variation in the rate of hydrolysis by micelles was treated by considering the Menger-Portnoy, Piszkiewicz's and Berezin kinetic models. The various thermodynamic parameters have also been evaluated. The added salts viz KCl, KNO3, K2SO4 enhanced the rate of reaction in the presence of cationic, anionic and non-ionic micelles. The kinetic parameters i. e. micellar pha...

Effect of Surfactants on Hydrolysis of Mono-N-ethyl-o-toluidine Phosphate

In the present paper we reported the method to prepare ZnO nanoparticles by alkaline precipitation method for the degradation of an azo dye. We have used ZnO nanoparticles assisted with UV light irradiation to investigate the photocatalytic degradation of azo dyes. The ZnO photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence.

Photocatalytic degradation of an azo dye with ZnO nanoparticles

The thin films of cadmium zinc selenide (Cd0.5Zn0.5Se) were prepared over glass substrates by chemical bath deposition technique. The Cd0.5Zn0.5Se thin films were doped with Gd at various doping values. The structural, morphological, compositional and optical properties were examined by XRD, SEM, EDX, UV-visible absorption and photolumines- cence studies, respectively. Various structural parameters were calculated and the band gaps for these thin films were estimated and found in the range of 2.19-1.79eV with respect to increasing doping values.

http://link.springer.com/content/pdf/10.1007/s11082-014-0093-y.pdf

Structural, morphological and optical studies on chemically deposited nanocrystalline Gd-doped Cd0.5Zn0.5Se thin films

Electronic, elastic, thermodynamic and vibrational properties of Li6BeZrF12: Insights from DFT-based computer simulation

Metal chalcogenide thin films of copper sulfide (CuxS) were grown on glass substrate using the chemical bath deposition. The CuxS thin film XRD studies reveal chalcocite low and covellite phases called as copper-rich and copper-poor form. The average grain size was calculated in the range of 8.87–69.65 nm. The optical band gap was estimated using Tauc's plot and found to be 3.02–4.06 eV. Optical properties exhibit that film find application in photovoltaic and photo thermal fields. AFM studies show formation of spherical shaped nanoparticle together with fine particles ranging 10 to 500 nm, evenly distributed showing homogeneity in polycrystalline thin film formation. SEM studies reveal spherical grain formation with cracks and pin holes at some places.

Ajaya Kumar Singh

Papers

Effect of Surfactants on Hydrolysis of Mono-N-ethyl-o-toluidine Phosphate

Photocatalytic degradation of an azo dye with ZnO nanoparticles

Structural, morphological and optical studies on chemically deposited nanocrystalline Gd-doped Cd0.5Zn0.5Se thin films

Electronic, elastic, thermodynamic and vibrational properties of Li6BeZrF12: Insights from DFT-based computer simulation

Synthesis, Morphological and Optical Properties of Nano-Crystalline Solid CuxS Thin Films