Narrow Results

Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein “clouds” surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed.

We study the merger rate of dark matter PIMBHs (Primordial Intermediate Mass Black Holes). We conclude that the black holes observed by LIGO in GW150914 and later events were probably not dark matter PIMBHs but rather the result of gravitational collapse of very massive stars. To study the PIMBHs by gravitational radiation will require a detector sensitive to frequencies below 10 Hz and otherwise more sensitive than LIGO. The LISA detector, expected to come online in 2034, will be useful at frequencies below 1 Hz but further gravitational wave detectors beyond LISA, sensitive up to 10 Hz, and higher strain sensitivity will be necessary to fully study dark matter.

The field of gravitational-wave astronomy has been opened up by gravitational-wave observations made with interferometric detectors. This review surveys the current state-of-the-art in gravitational-wave detectors and data analysis methods currently used by the Laser Interferometer Gravitational-Wave Observatory in the United States and the Virgo Observatory in Italy. These analysis methods will also be used in the recently completed KAGRA Observatory in Japan. Data analysis algorithms are developed to target one of four classes of gravitational waves. Short duration, transient sources include compact binary coalescences, and burst sources originating from poorly modeled or unanticipated sources. Long duration sources include sources which emit continuous signals of consistent frequency, and many unresolved sources forming a stochastic background. A description of potential sources and the search for gravitational waves from each of these classes are detailed.

Direct detection of gravitational waves from several compact binary coalescences has ushered in a new era of astronomy. It has opened up the possibility of detecting ultralight bosons, predicted by extensions of the Standard Model, from their gravitational signatures. This is of particular interest as some of these hypothetical particles could be components of dark matter that are expected to interact very weakly with Standard Model particles, if at all, but they would gravitate as usual. Ultralight bosons can trigger superradiant instabilities of rotating black holes and form bosonic clouds that would emit gravitational waves. In this paper, we present an overview of such instabilities as gravitational wave sources and assess the ability of current and future detectors to shed light on potential dark matter candidates.

In this paper, we examine the correlation functions associated with intensity interferometry and gravito-optics of gravitational wave (GW) signals from compact binary coalescences (CBC). Previous theoretical studies of the gravito-optics of GWs have concentrated on the characterization of both the classical and the nonclassical properties of signals from cosmological sources in the early Universe. These previous works assume a periodic signal similar to the signals studied widely in optics and quantum optics and do not apply to transient signals. We develop the gravito-optics of intensity correlations for descriptions of the detection of transient signals from CBC and apply these methods to calculate the two-point intensity correlations for the GW discovery. We also discuss the necessary theoretical work required for the description of the quantum gravito-optics of intensity correlations in the detection of signals from binary inspirals.

We study the problem of all-sky search in reference to a continuous gravitational wave (CGW) whose wave-form is known in advance. We employ the concept of fitting factor and study the variation in the bank of search templates with different Earth azimuth at t = 0. We found that the number of search templates varies significantly. Hence, accordingly, the computational demand for the search may be reduced up to two orders by time shifting the data.

We argue that the gravitational wave signal recently observed by the LIGO detectors provides a powerful tool to probe the fundamental structure of space and time. In particular, we properly model the inspiral phase of two merging black holes in a noncommutative spacetime and extract an upper bound on the scale of such quantum fuzziness at the order of the Planck scale. This improves previous constraints by $\sim 15$ orders of magnitude.

In this paper, we review the theoretical basis for generation of gravitational waves and the detection techniques used to detect a gravitational wave. To materialize this goal in a thorough way, we first start with a mathematical background for general relativity from which a clue for gravitational wave was conceived by Einstein. Thereafter, we give the classification scheme of gravitational waves such as (i) continuous gravitational waves, (ii) compact binary inspiral gravitational waves and (iii) stochastic gravitational wave. Necessary mathematical insight into gravitational waves from binaries is also dealt with which follows detection of gravitational waves based on the frequency classification. Ground-based observatories as well as space borne gravitational wave detectors are discussed in a length. We have provided an overview on the inflationary gravitational waves. In connection to data analysis by matched filtering there are a few highlights on the techniques, e.g. (i) random noise, (ii) power spectrum, (iii) shot noise and (iv) Gaussian noise. Optimal detection statistics for a gravitational wave detection is also in the pipeline of the discussion along with detailed necessity of the matched filter and deep learning.

Using an analysis from a physical and phenomenological viewpoint employing the renowned and recognized continuity of the Boscovich force curve, a new paradigm is formulated to explicate various physical phenomena in both the micro-world and the macro-world. Within this paradigm, an algorithm is established which produced a functional representation of the various atomic line spectra of hydrogen and the temperature dependent black-body energy distribution of radiation which compared very favorably with the experimental data. The Boscovichian points which are assumed to be endowed with certain characteristics move under the action of a force (acceleration) field that varies inversely proportional to the cube of the radius from the center of force which leads to an orbit described by an equiangular (logarithmic) spiral. This spiral consists of intercepts that correspond to stable and unstable points on the Boscovich curve. These intercepts are the roots of the equations employed and are described in the Pavia paper. Further representations also produced very favorable results for the photoelectric effect, (to be published). In addition, utilizing the shape of Boscovich’s “extended” curve of force, the prospect of the interpretation of the mysterious attractive and repulsive forces beyond the visible Newtonian region of space, often described in terms of “black holes”, “dark energy”, etc. is proposed. The recent LIGO experiments provides a means of using this extended Boscovich’s to analyze these results and is presented herein.

Over the past decade, gravitational wave detectors have undergone dramatic transitions in both sensitivity and scale — from laboratory-sized resonant bar detectors to kilometer-length-scale laser interferometers. The construction and operation of large-scale laser-interferometric gravitational wave detectors such as the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Virgo interferometer as well as others have enabled searches for extra-galactic gravitational waves with unprecedented range and sensitivity. Here, we review the present state of the global laser-interferometric gravitational wave detector network, highlight the results of recent science runs, and provide a preview of the state of the network in the coming decade and beyond.

The past decade has witnessed the successful operation of the first generation of large scale ground-based gravitational-wave interferometers — LIGO, Virgo, and GEO600 — each demonstrating remarkably sensitive, robust performance over a series of observing runs beginning in 2002 and continuing through 2011. Although gravitational waves have not yet been directly detected, searches by these detectors have established noteworthy limits on the possible emission of gravitational waves from astrophysical sources. Second generation instruments currently under construction such as Advanced LIGO, Advanced Virgo, and KAGRA will begin observing in the second half of this decade with sensitivities that are predicted to lead to direct detections of binary neutron star mergers and possibly other sources of gravitational waves.