Gravitational wave (GW) emission from close encounters (CEs) between neutron stars (NSs) and/or black holes (BHs) binary are recently being considered as new potential astrophysical sources for ground-based detectors. CEs are mostly part of three-body systems, constrained by a dense stellar environment. Their GW emission is the result of a dynamical capture, whose waveform is hard to model...
In spite of the fact that gravitational-wave (GW) interferometers detect GWs in a very complicated (and very clever) way, the final output (i.e. that used for data analysis, obtained after calibration and other processes) is up to now quite simple: the detected strain is linear in the two GW polarizations, which are multiplied by the corresponding antenna patterns which describe the detector’s...
If a significant fraction of dark matter is in the form of compact objects, they will cause microlensing effects in the gravitational-wave signals observable by LIGO and Virgo. From the nonobservation of microlensing signatures in the binary black hole events from the first two observing runs and the first half of the third observing run, we constrain the fraction of compact dark matter in the...
Cosmological parameters can be constrained if simultaneous access to distance and redshift measurements is achieved. Gravitational waves from compact binaries represent the so-called standard sirens, as their waveform provides direct information about the luminosity distance to the source. However, we do need some non gravitational information to break the degeneracy between source mass and...
A spinning gyro orbiting around a massive compact astrophysical body can capture the general relativistic effects around the central object. If the gyro rotates at some fixed orbit around the star, then the qualitative and quantitative nature of the overall gyro precession frequency can reveal various properties of the central object. If the central object has a companion, then the precession...
Primordial Black Holes (PBHs) maybe formed in the Early Universe during the so called radiation-dominated era, significantly before the appearance of the first nuclei and the first stars. The interest on this dark matter candidate was renewed after the first binary black hole gravitational gave event detected by the LIGO-Virgo Collaboration. In particular it was proposed that PBHs with masses...
The phenomena of standing waves are well known in a mechanical and electromagnetic setting where the wave has the maximum and minimum amplitude at the antinodes and nodes, respectively. In the context of the exact solution to Einstein's field equations, we analyze a spacetime that represents standing gravitational
waves in an expanding Universe. The study of the motion of free masses is...
Neutron stars are very dense objects found in the universe. These neutron stars can have very high angular velocity about their axis, such fast-spinning neutron stars are also known as pulsars. The rotation axis of a pulsar is defined as the axis around which a star rotates, similarly, we can define an axis called a magnetic axis, which is the axis along which the magnetic field lines...
We study the prospects of detecting continuous gravitational waves (CGWs) from spinning neutron stars, gravitationally lensed by the galactic supermassive black hole. Assuming various astrophysically motivated spatial distributions of galactic neutron stars, we find that CGW signals from a few ($\sim 0-6$) neutron stars should be strongly lensed. Lensing will produce two copies of the signal...
We report an experimental generation of squeezed light at 1550nm using a continuous-wave laser. An electric field noise reduction of 1.5 dB below the shot noise was observed. To generate squeezed light, we employed parametric down conversion (PDC) process where 775nm pump light is converted to 1550nm squeezed field. The 775nm pump was produced by second harmonic generation (SHG) in a single...
We present a multiple test for the targeted search of continuous gravitational waves from an ensemble of known pulsars, combining multidetector single pulsar statistics defined through the 5n-vector method. In order to maximize the detection probability, we describe a rank truncation method to select the most promising sources within the ensemble, based on the p-values computed for single...
In the current development of optical coatings for high precision instruments like GW interferometers thermal Brownian noise currently pose a limiting factor on the performances obtainable. In particular in the VIRGO experiment, in the 50-300 Hz region, thermal brownian noise act as the dominant contribution.
Since the Brownian noise is commonly attributed to the existence of many local...
