Data analysis of continuous gravitational wave: Fourier transform-I

We present the Fourier Transform of a continuous gravitational wave. We have analysed the data set for one day observation time and our analysis is applicable for arbitrary location of detector and source. We have taken into account the effects arising due to rotational as well as orbital motions of the earth.Comment: Accepted in MNRAS, 22 pages, 9 figure

Global parameter-space correlations of coherent searches for continuous gravitational waves

The space of phase-parameters (sky-position, frequency, spindowns) of a coherent matched-filtering search for continuous gravitational waves from isolated neutron stars shows strong global correlations (``circles in the sky''). In the local limit this can be analysed in terms of a parameter-space metric, but the global properties are less well studied. In this work we report on our recent progress in understanding these global correlations analytically for short to intermediate (less than a month, say) observation times and neglecting spindowns. The location of these correlation-circles in parameter-space is found to be determined mostly by the orbital velocity of the earth, while the spin-motion of the detector and the antenna-patterns only contribute significantly to the amplitude of the detection statistic along these circles.Comment: 10 pages, 6 figures; contribution to GWDAW9, submitted to CQ

Studies of structural, magnetic and dielectric properties of X-type Barium Zinc hexaferrite Ba2Zn2Fe28O46 powder prepared by combustion treatment method using ginger root extract as a green reducing agent

Various quantities of ginger (Zingiber officinale) root extract were used to prepare X-type Barium–Zinc hexaferrite with the chemical composition Ba2Zn2Fe28O46. The powders were prepared using a combustion treatment method, being pre-heated at 550 °C for 4 h with the ginger as a fuel, followed by final heating to 900 °C for 5 h and natural cooling to room temperature to obtain Ba2Zn2Fe28O46 hexagonal ferrite powder. The phase composition of heated powder samples was investigated by X-ray diffraction (XRD), indicating the formation of a mixture of X-type and hematite (α-Fe2O3). Up to 82.6%, X-ferrite was formed at 900 °C with 52.5 g of ginger root extract. Dielectric analysis of the prepared samples shows the frequency-dependent phenomena. All samples were hard magnets, with coercivity values (HC) between 262.2 and 318.3 kA m−1, and squareness ratios > 0.5. The sample prepared with 52.5 g ginger root extract possesses the highest value of saturation magnetisation (MS = 33.87 Am2 kg−1) in comparison with the other prepared samples. Therefore, ginger was shown to be a useful natural plant extract as a reducing fuel for the low-temperature synthesis of X-ferrites. The sample prepared with 35 g ginger root extract shows a broad loss tangent resonance peak between 10 kHz and 100 kHz, while other samples show loss tangent resonance peaks between 300 kHz and 2 MHz frequency range

A Study of the Gravitational Wave Pulsar Signal with orbital and spindown Effects

In this work we present analytic and numerical treatments of the gravitational wave signal from a pulsar which includes spindown. We consider phase corrections to a received monochromatic signal due to rotational and elliptical orbital motion of the Earth, as well as perturbations due to Jupiter and the Moon. We discuss the Fourier transform of such a signal, which is expressed in terms of well known special functions and lends itself to a tractable numerical analysis.Comment: 8 pages, 8 figures. Write-up of talk given at Theory Canada I, June 2005, University of British Columbi

A study of the gravitational wave form from pulsars II

We present analytical and numerical studies of the Fourier transform (FT) of the gravitational wave (GW) signal from a pulsar, taking into account the rotation and orbital motion of the Earth. We also briefly discuss the Zak-Gelfand Integral Transform. The Zak-Gelfand Integral Transform that arises in our analytic approach has also been useful for Schrodinger operators in periodic potentials in condensed matter physics (Bloch wave functions).Comment: 6 pages, Sparkler talk given at the Amaldi Conference on Gravitational waves, July 10th, 2001. Submitted to Classical and Quantum Gravit

On gravitational waves emitted by an ensemble of rotating neutron stars

We study the possibility to detect the gravitational wave background generated by all the neutron stars in the Galaxy with only one gravitational wave interferometric detector. The proposed strategy consists in squaring the detector's output and searching for a sidereal modulation. The shape of the squared signal is computed for a disk and a halo distribution of neutron stars. The required noise stability of the interferometric detector is discussed. We argue that a possible population of old neutron stars, originating from a high stellar formation rate at the birth of the Galaxy and not emitting as radio pulsars, could be detected by the proposed technique in the low frequency range of interferometric experiments.Comment: 14 pages, 2 PostScript figures, RevTeX, accepted for publication in Physical Review

Testing Scalar-Tensor Gravity with Gravitational-Wave Observations of Inspiralling Compact Binaries

Observations of gravitational waves from inspiralling compact binaries using laser-interferometric detectors can provide accurate measures of parameters of the source. They can also constrain alternative gravitation theories. We analyse inspiralling compact %binaries in the context of the scalar-tensor theory of Jordan, Fierz, Brans and Dicke, focussing on the effect on the inspiral of energy lost to dipole gravitational radiation, whose source is the gravitational self-binding energy of the inspiralling bodies. Using a matched-filter analysis we obtain a bound on the coupling constant $\omega_{\rm BD}$ of Brans-Dicke theory. For a neutron-star/black-hole binary, we find that the bound could exceed the current bound of $\omega_{\rm BD}>500$ from solar-system experiments, for sufficiently low-mass systems. For a $0.7 M_\odot$ neutron star and a $3 M_\odot$ black hole we find that a bound $\omega_{\rm BD} \approx 2000$ is achievable. The bound decreases with increasing black-hole mass. For binaries consisting of two neutron stars, the bound is less than 500 unless the stars' masses differ by more than about $0.5 M_\odot$. For two black holes, the behavior of the inspiralling binary is observationally indistinguishable from its behavior in general relativity. These bounds assume reasonable neutron-star equations of state and a detector signal-to-noise ratio of 10.Comment: 10 pages, (3 figures upon request), WUGRAV-94-

The effect of heat treatment on the microstructure and mechanical properties of 2d nanostructured au/nife system

Nanostructured NiFe film was obtained on silicon with a thin gold sublayer via pulsed electrodeposition and annealed at a temperature from 100 to 400◦C in order to study the effect of heat treatment on the surface microstructure and mechanical properties. High-resolution atomic force microscopy made it possible to trace stepwise evolving microstructure under the influence of heat treatment. It was found that NiFe film grains undergo coalescence twice—at ~100 and ~300°C—in the process of a gradual increase in grain size. The mechanical properties of the Au/NiFe nanostructured system have been investigated by nanoindentation at two various indentation depths, 10 and 50 nm. The results showed the opposite effect of heat treatment on the mechanical properties in the near-surface layer and in the material volume. Surface homogenization in combination with oxidation activation leads to abnormal strengthening and hardening-up of the near-surface layer. At the same time, a nonlinear decrease in hardness and Young’s modulus with increasing temperature of heat treatment characterizes the internal volume of nanostructured NiFe. An explanation of this phenomenon was found in the complex effect of changing the ratio of grain volume/grain boundaries and increasing the concentration of thermally activated diffuse gold atoms from the sublayer to the NiFe film. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0011

An investigation of uniform expansions of large order Bessel functions in Gravitational Wave Signals from Pulsars

In this work, we extend the analytic treatment of Bessel functions of large order and/or argument. We examine uniform asymptotic Bessel function expansions and show their accuracy and range of validity. Such situations arise in a variety of applications, in particular the Fourier transform of the gravitational wave signal from a pulsar. The uniform expansion we consider here is found to be valid in the entire range of the argument

Inhomogeneous Bulk Viscous Fluid Universe with Electromagnetic Field and Variable Λ\Lambda-Term

Cylindrically symmetric inhomogeneous cosmological model for bulk viscous fluid distribution with electromagnetic field is obtained. The source of the magnetic field is due to an electric current produced along the z-axis. $F_{12}$ is the non-vanishing component of electromagnetic field tensor. To get the deterministic solution, it has been assumed that the expansion $\theta$ in the model is proportional to the shear $\sigma$. The values of cosmological constant for these models are found to be small and positive at late time, which are consistent with the results from recent supernovae Ia observations. Physical and geometric aspects of the models are also discussed in presence and absence of magnetic field.Comment: 21 pages, 8 figure