**Gravitational** **wave** stochastic background from cosmological particle
decay

**gravitational**

**waves**(GW) via a new "memory effect" mechanism. Expand abstract.

**gravitational**

**waves**(GW) via a new "memory effect" mechanism. We calculate the spectral amplitude and slope of the resulting background, which is frequency-independent (flat). We discuss its potential observability and show that the resulting background might dominate the cosmological GW background at frequencies above about 10 GHz. Penrose has proposed a cosmological model in which dark matter particles have the Planck mass and decay into two gravitons [arXiv:1707.04169]. For these, the spectrum has an additional "direct" contribution from the decay products, which we also calculate. At low frequencies, this direct contribution also has a flat spectrum but with a much smaller amplitude than the memory part.

8/10 relevant

arXiv

2-OGC: Open **Gravitational**-**wave** Catalog of binary mergers from analysis
of public Advanced LIGO and Virgo data

**Gravitational**-

**wave**Catalog (2-OGC) of compact-binary coalescences, obtained from the complete set of public data from Advanced LIGO's first and second observing runs. For the first time we also search public data from the Virgo observatory. The sensitivity of our search benefits from updated methods of ranking candidate events including the effects of non-stationary detector noise and varying network sensitivity; in a separate targeted binary black hole merger search we also impose a prior distribution of binary component masses. We identify a population of 14 binary black hole merger events with probability of astrophysical origin $> 0.5$ as well as the binary neutron star merger GW170817. We confirm the previously reported events GW170121, GW170304, and GW170727 and also report GW151205, a new marginal binary black hole merger with a primary mass of $67^{+28}_{-17}\,\mathrm{M}_{\odot}$ that may have formed through hierarchical merger. We find no additional significant binary neutron star merger or neutron star--black hole merger events. To enable deeper follow-up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the sub-threshold population of candidates and posterior samples from parameter inference of the 30 most significant binary black hole candidates.

7/10 relevant

arXiv

Binary Neutron Star Mergers with Missing Electromagnetic Counterparts as Manifestations of Mirror World

**gravitation**ally, which is the reason why no electromagnetic signals accompanying

**gravitational**

**waves**from mergers with components composed of mirror matter are expected. Expand abstract.

**gravitational**

**wave**signal detectable by LIGO/VIRGO, emerged from the hidden mirror sector. Mirror particles do not interact with an ordinary observer except gravitationally, which is the reason why no electromagnetic signals accompanying

**gravitational**

**waves**from mergers with components composed of mirror matter are expected. Therefore, if the dark matter budget of the universe is mostly contributed by the mirror particles, we predict that only about one binary neutron star (neutron star - black hole) merger out of ten detectable by LIGO/VIRGO could be accompanied by a gamma ray burst. It seems the list of candidate events recorded by LIGO/VIRGO during third observational run supports our predictions.

7/10 relevant

arXiv

Massive deformations of Maass forms and Jacobi forms

**gravitational**

**waves**in string theory. Examples include massive Green's functions (that we write in terms of Kronecker-Eisenstein series) and massive modular graph functions.

4/10 relevant

arXiv

Joint constraint on primordial **gravitational** **waves** and polarization
rotation angle with current CMB polarization data

8/10 relevant

arXiv

Neutrino oscillations in **gravitational** **waves**

**gravitational**

**waves**(GWs). Expand abstract.

**gravitational**

**waves**(GWs). We rederive the quasiclassical equation for the evolution of the neutrino spin in various external fields in curved spacetime starting from the Dirac equation for a massive neutrino. Then, we consider neutrino spin oscillations in nonmoving and unpolarized matter, a transverse magnetic field, and a plane GW. We show that a parametric resonance can take place in this system. We also study neutrino flavor oscillations in GWs. The equation for the density matrix of flavor neutrinos is solved when we discuss the neutrino interaction with stochastic GWs emitted by coalescing supermassive black holes. We find the fluxes of cosmic neutrinos, undergoing flavor oscillations in such a

**gravitational**background, which can be potentially measured by a terrestrial detector. Some astrophysical applications of our results are considered.

10/10 relevant

arXiv

Data Analysis Implications of Moderately Eccentric **Gravitational** **Waves**

**gravitational**

**wave**events observable by ground-based detectors will be emitted by compact binaries in quasi-circular orbits, the growing number of detections suggests the possibility of detecting

**waves**from binaries with non-negligible orbital eccentricity in the near future. Several

**gravitational**

**wave**models incorporate the effects of small orbital eccentricities ($e \lesssim 0.2$), but these models may not be sufficient to analyze

**waves**from systems with moderate eccentricity. We recently developed a

**gravitational**

**wave**model that faithfully accounts for eccentric corrections in the moderate eccentricity regime ($e \lesssim 0.8$ for certain source masses) at 3rd post-Newtonian order. Here we consider the data analysis implications of this particular waveform model by producing and analyzing posteriors via Markov Chain Monte Carlo methods. We find that the accuracy to which eccentricity and source masses can be measured can increase by 2 orders of magnitude with increasing eccentricity of the signal. We also find that signals with low eccentricity can be confidently identified as eccentric as soon as their eccentricity exceeds 0.008 (0.05) for low (high) mass systems, suggesting eccentric detections are likely to come first from low-mass systems. We complete our analysis by investigating the systematic (mismodeling) error inherent in our post-Newtonian model, finding that for signals with a signal-to-noise ratio of 15, the systematic error is below the statistical error for eccentricities as high as 0.8 (0.5) for low (high) mass systems. We also investigate the systematic error that arises from using a model that neglects eccentricity when the signal is truly eccentric, finding that the systematic error exceeds the statistical error in mass for eccentricities as small as 0.02.

10/10 relevant

arXiv

Radiation from Global Topological Strings using Adaptive Mesh Refinement: Methodology and Massless Modes

**gravitational**

**waves**produced by cosmic string networks.

4/10 relevant

arXiv

General Perfect Fluid Perturbations of Homogeneous and Orthogonal Locally Rotationally Symmetric Class II Cosmologies

**gravitational**

**waves**on the anisotropic background in the same manner as in the case without vorticity, whereas vorticity gives a first order disturbance of sonic

**wave**s. Expand abstract.

**gravitational**

**waves**on the anisotropic background in the same manner as in the case without vorticity, whereas vorticity gives a first order disturbance of sonic

**waves**.

4/10 relevant

arXiv

An arm length stabilization system for KAGRA and future
**gravitational**-**wave** detectors

**gravitational**

**wave**(GW) detectors require a complex interferometer configuration with multiple coupled optical cavities. Since achieving the resonances of the arm cavities is the most challenging among the lock acquisition processes, the scheme called arm length stabilization (ALS) had been employed for lock acquisition of the arm cavities. We designed a new type of the ALS, which is compatible with the interferometers having long arms like the next generation GW detectors. The features of the new ALS are that the control configuration is simpler than those of previous ones and that it is not necessary to lay optical fibers for the ALS along the kilometer-long arms of the detector. Along with simulations of its noise performance, an experimental test of the new ALS was performed utilizing a single arm cavity of KAGRA. This paper presents the first results of the test where we demonstrated that lock acquisition of the arm cavity was achieved using the new ALS and residual noise was measured to be $8.2\,\mathrm{Hz}$ in units of frequency, which is smaller than the linewidth of the arm cavity and thus low enough to lock the full interferometer of KAGRA in a repeatable and reliable manner.

7/10 relevant

arXiv