Found 946 results, showing the newest relevant preprints. Sort by relevancy only.Update me on new preprints

BSM with Cosmic Strings: Heavy, up to EeV mass, Unstable Particles

Unstable heavy particles well above the TeV scale are unaccessible experimentally. Expand abstract.

Unstable heavy particles well above the TeV scale are unaccessible experimentally. So far, Big-Bang Nucleosynthesis (BBN) provides the strongest limits on their mass and lifetime, the latter being shorter than 0.1 second. We show how these constraints could be potentially tremendously improved by the next generation of

**Gravitational**-**Wave**(GW) interferometers, extending to lifetimes as short as $10^{-16}$ second. The key point is that these particles may have dominated the energy density of the universe and have triggered a period of matter domination at early times, until their decay before BBN. The resulting modified cosmological history compared to the usually-assumed single radiation era would imprint observable signatures in stochastic**gravitational**-**wave**backgrounds of primordial origin. In particular, we show how the detection of the GW spectrum produced by long-lasting sources such as cosmic strings would provide a unique probe of particle physics parameters. When applied to specific particle production mechanisms in the early universe, these GW spectra could be used to derive new constraints on many UV extensions of the Standard Model. We illustrate this on a few examples, such as supersymmetric models where the mass scale of scalar moduli and gravitino can be constrained up to $10^{10}$ GeV. Further bounds can be obtained on the reheating temperature of models with only-gravitationally-interacting particles as well as on the kinetic mixing of heavy dark photons at the level of $10^{-18}$.6 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Science Case for the Einstein Telescope

ET will explore the universe with

**gravitational****waves**up to cosmological distances. Expand abstract. The Einstein Telescope (ET), a proposed European ground-based

**gravitational**-**wave**detector of third-generation, is an evolution of second-generation detectors such as Advanced LIGO, Advanced Virgo, and KAGRA which could be operating in the mid 2030s. ET will explore the universe with**gravitational****waves**up to cosmological distances. We discuss its main scientific objectives and its potential for discoveries in astrophysics, cosmology and fundamental physics.7 days ago

6/10 relevant

arXiv

6/10 relevant

arXiv

Probing the cosmic opacity from Future **Gravitational** **Wave** Standard
Sirens

In this work, using the Gaussian Process, we explore the potentiality of future gravitational wave (GW) measurement to probe cosmic opacity through comparing its opacity-free luminosity distance (LD) with the opacity-dependent one from type Ia supernovae (SNIa). Expand abstract.

In this work, using the Gaussian Process, we explore the potentiality of future

**gravitational****wave**(GW) measurement to probe cosmic opacity through comparing its opacity-free luminosity distance (LD) with the opacity-dependent one from type Ia supernovae (SNIa). GW data points are simulated from the third generation Einstein Telescope, and SNIa data are taken from the Joint Light Analysis (JLA) or Pantheon compilation. The advantages of using Gaussian Process are that one may match SNIa data with GW data at the same redshift and use all available data to probe cosmic opacity. We obtain that the error bar of the constraint on cosmic opacity can be reduced to $\sigma_{\epsilon}\sim 0.011$ and $0.006$ at $1\sigma$ confidence level (CL) for JLA and Pantheon respectively in a cosmological-independent way. Thus, the future GW measurements can give competitive results on the cosmic opacity test. Furthermore, we propose a method to probe the spatial homogeneity of the cosmic transparency through comparing the reconstructed LD from the mock GW with the reconstructed one from SNIa data in a flat $\Lambda$CDM with the Gaussian Process. The result shows that a transparent universe is favored at $1\sigma$ CL, although the best-fit value of cosmic opacity is redshift-dependent.8 days ago

9/10 relevant

arXiv

9/10 relevant

arXiv

Beyond the Standard Models with Cosmic Strings

We consider the impact of particle production on the

**gravitational**-**wave**emission by loops. Expand abstract. We examine which information on the early cosmological history can be extracted from the potential measurement by third-generation

**gravitational**-**wave**observatories of a stochastic**gravitational****wave**background (SGWB) produced by cosmic strings. We consider a variety of cosmological scenarios breaking the scale-invariant properties of the spectrum, such as early long matter or kination eras, short intermediate matter and inflation periods inside a radiation era, and their specific signatures on the SGWB. This requires to go beyond the usually-assumed scaling regime, to take into account the transient effects during the change of equation of state of the universe. We compute the time evolution of the string network parameters and thus the loop-production efficiency during the transient regime, and derive the corresponding shift in the turning-point frequency. We consider the impact of particle production on the**gravitational**-**wave**emission by loops. We estimate the reach of future interferometers LISA, BBO, DECIGO, ET and CE and radio telescope SKA to probe the new physics energy scale at which the universe has experienced changes in its expansion history. We find that a given interferometer may be sensitive to very different energy scales, depending on the nature and duration of the non-standard era, and the value of the string tension. It is fascinating that by exploiting the data from different GW observatories associated with distinct frequency bands, we may be able to reconstruct the full spectrum and therefore extract the values of fundamental physics parameters.8 days ago

7/10 relevant

arXiv

7/10 relevant

arXiv

Gaussian processes reconstruction of modified **gravitational** **wave**
propagation

Recent work has shown that modified gravitational wave (GW) propagation can be a powerful probe of dark energy and modified gravity, specific to GW observations. Expand abstract.

Recent work has shown that modified

**gravitational****wave**(GW) propagation can be a powerful probe of dark energy and modified gravity, specific to GW observations. We use the technique of Gaussian processes, that allows the reconstruction of a function from the data without assuming any parametrization, to measurements of the GW luminosity distance from simulated joint GW-GRB detections, combined with measurements of the electromagnetic luminosity distance by simulated DES data. For the GW events we consider both a second-generation LIGO/Virgo/Kagra (HVLKI) network, and a third-generation detector such as the Einstein Telescope. We find that the HVLKI network at target sensitivity, with $O(15)$ neutron star binaries with electromagnetic counterpart, could already detect deviations from GR at a level predicted by some modified gravity models, and a third-generation detector such as ET would have a remarkable discovery potential. We discuss the complementarity of the Gaussian processes technique to the $(\Xi_0,n)$ parametrization of modified GW propagation.16 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

High accuracy on $H_0$ constraints from **gravitational** **wave** lensing
events

In light of the newly opened and rapidly growing GW window in multi-messenger astronomy, in order to fully take advantage of the new opportunities we are provided with, new ideas are required for a better and deeper employ of the state-of-the-art probes we handle. Expand abstract.

In light of the newly opened and rapidly growing GW window in multi-messenger astronomy, in order to fully take advantage of the new opportunities we are provided with, new ideas are required for a better and deeper employ of the state-of-the-art probes we handle. Following this goal, here we suggest a method to constrain the cosmological background, and the Hubble constant in particular, by future observations of gravitationally lensed radiation emitted by a single source in both the

**gravitational****wave**and the electromagnetic regimes. The lensing of the**gravitational****wave**radiation, in fact, can leave a clear imprinting in the corresponding waveform, and we want to analyze if such kind of measurements can be successfully employed to better constrain the cosmological background. Thus, by making use of**wave**optics for the**gravitational****wave**lensed signal, and of standard geometrical optics approximation for the electromagnetic one, we study the impact of different cosmological parameters on the value of the arrival time delay due to**gravitational**lensing, given specific GW frequencies, mass models of the lens, and redshifts and positions (with respect to the lens) of the source. Although the rate of lensing of**gravitational****waves**is expected to be low, we show that even one single event could provide us with an uncertainty on $H_0$ comparable with present independent probes in a "pessimistic" scenario (with a pulsar population similar to present Pulsar Timing Array state), and of two orders smaller in an optimistic one (with a number of observed pulsars as large as that expected from the Square Kilometer Array). Thus, its role in the solution of the Hubble tension could be decisive.16 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

**Gravitational** **Waves** from Hierarchical Triple Systems with Kozai-Lidov
Oscillation

We study

**gravitational****waves**from a hierarchical three-body system up to first-order postNewtonian approximation. Expand abstract. We study

**gravitational****waves**from a hierarchical three-body system up to first-order postNewtonian approximation. Under certain conditions, the existence of a nearby third body can cause periodic exchange between eccentricity of an inner binary and relative inclination, known as Kozai-Lidov oscillations. We analyze features of the waveform from the inner binary system undergoing such oscillations. We find that variation caused due to the tertiary companion can be observed in the**gravitational**waveforms and energy spectra, which should be compared with those from isolated binaries and coplanar three-body system. The detections from future space interferometers will make possible the investigation of the**gravitational****wave**spectrum in mHz range and may fetch signals by sources addressed.17 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Quantum effects in gravity **waves**

Fluctuations in the electric field due to interaction with a

**gravitational****wave**both in a coherent and squeezed states are then calculated, and it is shown that the field experiences infinite revivals of squeezing. Expand abstract. We propose a simple experiment in which the interaction of a

**gravitational****wave**with the electromagnetic field in a cavity takes the form of the standard quantum optomechanical hamiltonian. Fluctuations in the electric field due to interaction with a**gravitational****wave**both in a coherent and squeezed states are then calculated, and it is shown that the field experiences infinite revivals of squeezing. Since revivals are a quantum mechanical effect, measuring these "gravitationally induced revivals" would provide evidence on the quantum nature of gravity.17 days ago

5/10 relevant

arXiv

5/10 relevant

arXiv

Astrometric Effects of **Gravitational** **Wave** Backgrounds with non-Luminal
Propagation Speeds

These correlations are quantified and investigated for backgrounds of

**gravitational****waves**with sub- and super-luminal group velocities. Expand abstract. A passing

**gravitational****wave**causes a deflection in the apparent astrometric positions of distant stars. The effect of the speed of the**gravitational****wave**on this astrometric shift is discussed. A stochastic background of**gravitational****waves**would result in a pattern of astrometric deflections which are correlated on large angular scales. These correlations are quantified and investigated for backgrounds of**gravitational****waves**with sub- and super-luminal group velocities. The statistical properties of the correlations are depicted in two equivalent and related ways: as correlation curves and as angular power spectra. Sub-(super-)luminal**gravitational****wave**backgrounds have the effect of enhancing (suppressing) the power in low-order angular modes. Analytical representations of the redshift-redshift and redshift-astrometry correlations are also derived. The potential for using this effect for constraining the speed of gravity is discussed.19 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

**Gravitational** **wave**forms of binary neutron star inspirals using PN Tidal
Splicing

The tidal deformations of neutron stars within an inspiraling compact binary alter the orbital dynamics, imprinting a signature on the

**gravitational****wave**signal. Expand abstract. The tidal deformations of neutron stars within an inspiraling compact binary alter the orbital dynamics, imprinting a signature on the

**gravitational****wave**signal. Modeling this signal could be done with numerical-relativity simulations, but these are too computationally expensive for many applications. Analytic post-Newtonian treatments are limited by unknown higher-order non-tidal terms. This paper further builds upon the "Tidal Splicing" model in which post-Newtonian tidal terms are "spliced" onto numerical relativity simulations of black-hole binaries. We improve on previous treatments of tidal splicing by including spherical harmonic modes beyond the (2,2) mode, expanding the Post-Newtonian expressions for tidal effects to 2.5 order, including dynamical tide corrections, and adding a partial treatment of the spin-tidal dynamics. Furthermore, instead of numerical relativity simulations, we use the spin-aligned BBH surrogate model "NRHybSur3dq8" to provide the BBH waveforms that are input into the tidal slicing procedure. This allows us to construct spin-aligned, inspiraling TaylorT2 and TaylorT4 splicing waveform models that can be evaluated quickly. These models are tested against existing binary neutron star and black hole-neutron star simulations. We implement the TaylorT2 splicing model as an extention to "NRHybSur3dq8", creating a model that we call "NRHybSur3dq8Tidal".19 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv