Laser Interferometer Gravitational Observatory Research Articles

Astrophysical stochastic gravitational wave background

AbstractThe stochastic gravitational wave background produced by supernovas, magnetars, and merger of binaries constituted of a pair of compact objects is reviewed and updated. The merger of systems composed of two black holes dominates by far the background signal, whose amplitude in the range 10–100 Hz is above the sensitivity of the planned Einstein laser interferometer (ET). The background signal at 25 Hz estimated by the laser interferometric gravitational observatory (LIGO)‐VIRGO collaboration, based on the available merger detection data, is in good agreement with the present theoretical predictions.

Gravitational Waves and Engineering Aspects of Thermal and Earth Quakes of Earth

The recent discovery of gravitational waves announced on February 11th 2016 forms the background of Einstein’s discovery about a century ago forms the background. To use the strain measured on the earth from Laser Interferometer Gravitational Observatory and determine the energy given the Earth from passing gravitational waves. A finite element model of the Earth is made and presented. The results obtained are discussed over the warming of Earth albeit slowly. This energy is responsible in breaking of Pangea over 300 million years ago and bringing it to the present continental positions as in Wegener’s Continental Drift Theory. The continental drift of the tectonic plates with each passing of gravitational waves and imparting energy causes Earthquakes.

Post-Newtonian approximation of gravitational waves from the inspiral phase

We review the post-Newtonian (PN) expansion for the relativistic correction to the motion of a binary system of black holes. Using the Newtonian formalism, we derive the orbital equations for the 2nd order PN corrections, considering small velocities and weak fields. From a wave equation obtained by the post-Newtonian approximation, we find the h+ and h× polarization of the Gravitational Waves (GW) which could be detected by Laser Interferometer Gravitational Observatory (LIGO).

An Information Retrieval and Recommendation System for Astronomical Observatories

Abstract We present a machine-learning-based information retrieval system for astronomical observatories that tries to address user-defined queries related to an instrument. In the modern instrumentation scenario where heterogeneous systems and talents are simultaneously at work, the ability to supply people with the right information helps speed up the tasks for detector operation, maintenance, and upgradation. The proposed method analyzes existing documented efforts at the site to intelligently group related information to a query and to present it online to the user. The user in response can probe the suggested content and explore previously developed solutions or probable ways to address the present situation optimally. We demonstrate natural language-processing-backed knowledge rediscovery by making use of the open source logbook data from the Laser Interferometric Gravitational Observatory (LIGO). We implement and test a web application that incorporates the above idea for LIGO Livingston, LIGO Hanford, and Virgo observatories.

Charge neutralization in vacuum for non-conducting and isolated objects using directed low-energy electron and ion beams

We propose using ions and electrons of energy 1 eV–10 eV for neutralizing the charges on the non-conducting or isolated surfaces of high-sensitivity experiments. The mirror surfaces of the test masses of the laser interferometer gravitational observatory are used as an example of the implementation of this method. By alternatively directing beams of positive and negative charges towards the mirror surfaces, we ensure the neutralization of the total charge as well as the equalization of the surface charge distribution to within a few eV of the potential of the ground reference of the vacuum system. This method is compatible with operation in high vacuum, does not require measuring the potential of the mirrors and is expected not to damage sensitive optical surfaces.

Mapping thegravitational-wave background

The gravitational-wave sky is expected tohave isolated bright sources superimposedon a diffuse gravitational-wavebackground. The background radiation hastwo components: a confusion limitedbackground from unresolved astrophysicalsources; and a cosmological componentformed during the birth of the universe. Amap of the gravitational-wave backgroundcan be made by sweeping agravitational-wave detector across thesky. The detector output is a complicatedconvolution of the sky luminositydistribution, the detector responsefunction and the scan pattern. Here westudy the general deconvolution problem,and show how LIGO (laser interferometricgravitational observatory) and LISA (laserinterferometer space antenna) can be usedto detect anisotropies in thegravitational-wave background.

Detection of anisotropies in the gravitational-wave stochastic background

By correlating the signals from a pair of gravitational-wave detectors, one can undertake sensitive searches for a stochastic background of gravitational radiation. If the stochastic background is anisotropic, then this correlated signal varies harmonically with the earth's rotation. We calculate how the harmonics of this varying signal are related to the multipole moments which characterize the anisotropy, and give a formula for the signal-to-noise ratio of a given harmonic. The specific case of the two LIGO (Laser Interferometric Gravitational Observatory) detectors, which will begin operation around the year 2000, is analyzed in detail. We consider two possible examples of anisotropy. If the gravitational-wave stochastic background contains a dipole intensity anisotropy whose origin (like that of the Cosmic Background Radiation) is motion of our local system, then that anisotropy will be observable by the advanced LIGO detector (with 90% confidence in one year of observation) if \Omega_{gw} > 5.3 \times 10^{-8} h_{100}^{-2}. We also study the signal produced by stochastic sources distributed in the same way as the luminous matter in the galactic disk, and in the same way as the galactic halo. The anisotropy due to sources distributed as the galactic disk or as the galactic halo will be observable by the advanced LIGO detector (with 90% confidence in one year of observation) if \Omega_{gw} > 1.8 \times 10^{-10} h_{100}^{-2} or \Omega_{gw} > 6.7 \times 10^{-8} h_{100}^{-2}, respectively.

Spin effects in the inspiral of coalescing compact binaries.

We derive the contributions of spin-orbit and spin-spin coupling to the gravitational radiation from coalescing binary systems of spinning compact objects. We calculate spin effects in the symmetric, trace-free radiative multipoles that determine the gravitational waveform, and the rate of energy loss. Assuming a balance between energy radiated and orbital energy lost, we determine the spin effects in the evolution of the orbital frequency and orbital radius. Assuming that a laser interferometric gravitational observatory can track the gravitational-wave frequency (twice the orbital frequency) as it sweeps through its sensitive bandwidth between about 10 Hz and one kHz, we estimate the accuracy with which the spins of the component bodies can be determined from the gravitational-wave signal.