scholarly journals Novel directed search strategy to detect continuous gravitational waves from neutron stars in low- and high-eccentricity binary systems

2017 ◽  
Vol 95 (12) ◽  
Author(s):  
Paola Leaci ◽  
Pia Astone ◽  
Sabrina D’Antonio ◽  
Sergio Frasca ◽  
Cristiano Palomba ◽  
...  

2001 ◽  
Vol 10 (04) ◽  
pp. 381-441 ◽  
Author(s):  
NILS ANDERSSON ◽  
KOSTAS D. KOKKOTAS

In this review we summarize the current understanding of the gravitational-wave driven instability associated with the so-called r-modes in rotating neutron stars. We discuss the nature of the r-modes, the detailed mechanics of the instability and its potential astrophysical significance. In particular we discuss results regarding the spin-evolution of nascent neutron stars, the detectability of r-mode gravitational waves and mechanisms limiting the spin-rate of accreting neutron stars in binary systems.



2000 ◽  
Vol 177 ◽  
pp. 579-584
Author(s):  
V. Kalogera

AbstractThe coalescence of close binary systems with two compact objects (neutron stars and black holes) are considered to be promising sources of gravitational waves for the currently built laser interferometers. Here, I review the current Galactic coalescence estimates derived both theoretically and empirically. I discuss the uncertainties involved as well as ways of obtaining an upper limit to the coalescence rate of two neutron stars.



Author(s):  
Rabinarayan Swain ◽  
Priyasmita Panda ◽  
Hena Priti Lima ◽  
Bijayalaxmi Kuanar ◽  
Biswajit Dalai

Detection of Gravitational waves opened a new path for cosmological study in a new approach. From the detection of gravitational waves signal by advanced LIGO, its research climbed the peak. After the collaboration of LIGO and Virgo, several observations get collected from different sources of binary systems like black holes, binary neutron stars even both binary black hole and neutron star. The rigorous detection of gravitational signals may provide an additional thrust in the study of complex binary systems, dark matter, dark energy, Hubble constant, etc. In this review paper, we went through multiple research manuscripts to analyze gravitational wave signals. Here we have reviewed the history and current situation of gravitational waves detection, and we explained the concept and process of detection. Also, we go through different parts of a detector and their working. Then multiple gravitational wave signals are focused, originated from various sources and then found correlation between them. From this, the contribution of gravitational waves in different fields like complex binary systems (black holes, neutron stars), dark matter, dark energy and Hubble Constant have been discussed in this manuscript.





2012 ◽  
Vol 8 (S291) ◽  
pp. 477-479
Author(s):  
Keith Riles

AbstractThe LIGO Scientific Collaboration and Virgo Collaboration have carried out joint searches in LIGO and Virgo data for periodic continuous gravitational waves. These analyses range from targeted searches for gravitational-wave signals from known pulsars, for which precise ephemerides from radio or X-ray observations are used in matched filters, to all-sky searches for unknown neutron stars, including stars in binary systems. Between these extremes lie directed searches for known stars of unknown spin frequency or for new unknown sources at specific locations, such as near the galactic center or in globular clusters. Recent and ongoing searches of each type will be summarized, along with prospects for future searches using data from the Advanced LIGO and Virgo detectors.



2006 ◽  
Vol 15 (07) ◽  
pp. 1047-1051 ◽  
Author(s):  
G. S. BISNOVATYI-KOGAN

The most precise measurements are obtained at present by timing of radiopulsars in binary systems with two neutron stars. The timing measurements of the Taylor–Hulse pulsar B1913+16 gave the most precise results on testing of general relativity (GR), finding implicit proof of existence of gravitational waves. We show that the available results of existing measurements, obtained to the year 1993, in combination with the results of the Mariner 10 in 1992, give the boundaries for the variation of the gravitational constant Ġ/G (within) the limits (-0.6 –+2) × 10-12 yr -1.



2011 ◽  
Vol 7 (S285) ◽  
pp. 103-103
Author(s):  
Benjamin W. Stappers

AbstractPulsars can be considered as the ultimate time-variable source. They show variations on time-scales ranging from nanoseconds to as long as years, and they emit over almost the entire electromagnetic spectrum. The dominant modulation is associated with the rotation period, which can vary from slighty more than a millisecond to upwards of ten seconds (if we include the magnetars). Variations on time-scales shorter than the pulse period are mostly associated with emission processes and are manifested as giant pulses, microstructure and sub-pulses (to name a few). On time-scales of a rotation to a few hundred rotations are other phenomena also associated with the emission, such as nulling, moding, drifting and intermittency.By probing these and slightly longer time-scales we find that pulsars exhibit “glitches”, which are rapid variations in spin rates. They are believed to be related to the interaction between the superfluid interior of the neutron star and the outer crust. Detailed studies of glitches can reveal much about the properties of the constituents of neutron stars—the only way to probe the physics of material at such extreme densities. Time-scales of about an hour or longer reveal that some pulsars are in binary systems, in particular the most rapidly rotating systems. Discovering and studying those binary systems provides vital clues to the evolution of massive stars, while some of the systems are also the best probes of strong-field gravity theories; the elusive pulsar-black hole binary would be the ultimate system.Pulsars are tools that allow us to probe a range of phenomena and time-scales. It is possible to measure the time of arrival of pulses from some pulsars to better than a few tens of nanoseconds over years, making them some of the most accurate clocks known. Concerning their rotation, deviations from sphericity may cause pulsars to emit gravitational waves which might then be detected by next-generation gravitational-wave detectors. Pulsars themselves can be used as the arms of a Galactic-scale gravitational-wave detector. Measuring correlated deviations in the arrival times of pulses from a number of pulsars distributed throughout the Galaxy could give rise to a direct detection of the stochastic gravitational-wave background, which is associated with the astrophysics of the early Universe—most likely from supermassive black-hole binary systems, but potentially also from cosmic strings. While they are famed for their clock-like rotational stability, some pulsars—in particular the more youthful ones—exhibit modulation in pulse arrival times, often called timing noise. It was recently demonstrated that in at least some cases this variability is deterministic and is associated with modulations in the pulsar emission properties and the spin-down rate. This breakthrough may lead to further improvements in the precision which can be achieved with pulsar timing, and enhance still further the ability to test theories of gravity directly and to make a direct detection of gravitational waves.I presented some of the history of what is known about the variations in pulsars on all these time-scales and reviewed some of the recent achievements in our understanding of the phenomena. I also highlighted how new transients associated with radio-emitting neutron stars are being discovered, and how other transient sources are being identified by the same techniques. These continued improvements have come about without new telescopes, but the next generation of very sensitive wide-field instruments will permit observational cadences which will reveal many new manifestations and will further revolutionise our understanding of this class of objects which have such high astrophysical potential.





2008 ◽  
Vol 7 (1) ◽  
pp. 64-70
Author(s):  
Kenath Arun

This paper shall look into the systems of compact astrophysical objects (black holes, neutron stars and white dwarfs) concerning mainly with binary systems. Determination of the orbital periods, velocities, etc, for such systems and also, the energy lost from the system through gravitational waves has been made, From the concept of energy loss, the merger of the two black holes in the system has been considered and the typical time required for the merger is calculated.



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