Two dimensional **gravity** **waves** at low regularity I: Energy estimates

**wave**equations in two space dimensions. Expand abstract.

**wave**equations in two space dimensions. Our focus here is on sharp cubic energy estimates. Precisely, we introduce and develop the techniques to prove a new class of energy estimates, which we call \emph{balanced cubic estimates}. This yields a key improvement over the earlier cubic estimates of Hunter-Ifrim-Tataru [12], while preserving their scale invariant character and their position-velocity potential holomorphic coordinate formulation. Even without using any Strichartz estimates, these results allow us to significantly lower the Sobolev regularity threshold for local well-posedness, drastically improving earlier results obtained by Alazard-Burq-Zuily [3, 4], Hunter-Ifrim-Tataru [12] and Ai [2].

7/10 relevant

arXiv

A Morawetz inequality for **gravity**-capillary water **waves** at low Bond
number

**gravity**

**waves**. Expand abstract.

**gravity**-capillary water

**waves**equations in their Hamiltonian formulation, addressing the general question of proving Morawetz inequalities. We continue the analysis initiated in our previous work, where we have established local energy decay estimates for

**gravity**

**waves**. Here we add surface tension and prove a stronger estimate with a local regularity gain, akin to the smoothing effect for dispersive equations. Our main result holds globally in time and holds for genuinely nonlinear waves, since we are only assuming some very mild uniform Sobolev bounds for the solutions. Furthermore, it is uniform both in the infinite depth limit and the zero surface tension limit.

5/10 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.

8/10 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.

7/10 relevant

arXiv

Probing multi-step electroweak phase transition with multi-peaked
primordial **gravitational** **waves** spectra

**gravitational**

**waves**are considered as a phenomenologically relevant source of information about the dynamics of sequential phase transitions in the early Universe. Expand abstract.

**gravitational**

**waves**are considered as a phenomenologically relevant source of information about the dynamics of sequential phase transitions in the early Universe. In particular, such signatures trace back to specific patterns of the first-order electroweak phase transition in the early Universe occurring in multiple steps. Such phenomena appear to be rather generic in multi-scalar extensions of the Standard Model. In a particularly simple extension of the Higgs sector, we have identified and studied the emergence of sequential long- and short-lasting transitions as well as their fundamental role in generation of multi-peaked structures in the primordial

**gravitational**-

**wave**spectrum. We discuss the potential detectability of these signatures by the next generation of

**gravitational**-

**wave**interferometers.

8/10 relevant

arXiv

Continuous **gravitational** **waves** from neutron stars: current status and
prospects

**gravitational**

**waves**searches, current LIGO and Virgo strategies of the data analysis and future prospects are reviewed in this work. Expand abstract.

**Gravitational**

**waves**astronomy allows us to study objects and events invisible in electromagnetic

**waves**. It may be crucial to validate the theories and models of the most mysterious and extreme matter in the Universe: the neutron stars. In addition to inspirals and mergers of neutrons stars, there are currently a few proposed mechanisms that can trigger radiation of long-lasting

**gravitational**radiation in neutron stars, like e.g., elastically and/or magnetically-driven deformations - mountains on the stellar surface supported by the elastic strain or magnetic field, free precession, or unstable oscillation modes (e.g. the r-modes). Astrophysical motivation for continuous

**gravitational**

**waves**searches, current LIGO and Virgo strategies of the data analysis and future prospects are reviewed in this work.

7/10 relevant

arXiv

**Gravitational** **Wave** Anisotropies from Primordial Black Holes

**gravitational**

**waves**would suggest that primordial black holes may not comply the totality of the dark matter. Expand abstract.

**gravitational**

**waves**is generated whenever primordial black holes are created in the early universe thanks to a small-scale enhancement of the curvature perturbation. We calculate the anisotropies and non-Gaussianity of such stochastic

**gravitational**

**waves**background which receive two contributions, the first at formation time and the second due to propagation effects. We conclude that a sizeable magnitude of anisotropy and non-Gaussianity in the

**gravitational**

**waves**would suggest that primordial black holes may not comply the totality of the dark matter.

8/10 relevant

arXiv

Constraining axion inflation with **gravitational** **waves** across 29 decades
in frequency

**gravitational**

**waves**generated by efficient gauge preheating after axion inflation generically contribute significantly to the effective number of relativistic degrees of freedom $N_\mathrm{eff}$. We show that, with existing Planck limits,

**gravitational**

**waves**from preheating already place the strongest constraints on the inflaton's possible axial coupling to gauge fields. We demonstrate that gauge preheating can completely reheat the Universe regardless of the inflationary potential. Further, we quantify the variation of the efficiency of

**gravitational**

**wave**production from model to model and show that it is correlated with the tensor-to-scalar ratio. In particular, when combined with constraints on models whose tensor-to-scalar ratios would be detected by next-generation cosmic microwave background experiments, $r\gtrsim 10^{-3}$, constraints from $N_\mathrm{eff}$ will probe or rule out the entire coupling regime for which gauge preheating is efficient.

10/10 relevant

arXiv

Continuous **Gravitational** **Waves** and Magnetic Monopole Signatures from
Single Neutron Stars

**gravitational**

**waves**which may last decades, and may be observable in current or future detectors. Expand abstract.

**gravitational**

**waves**from single neutron stars, apart from their monumental astrophysical significance, could also shed light on fundamental physics and exotic particle states. One such avenue is based on the fact that magnetic fields cause deformations of a neutron star, which results in a magnetic-field-induced quadrupole ellipticity. If the magnetic and rotation axes are different, this quadrupole ellipticity may generate continuous

**gravitational**

**waves**which may last decades, and may be observable in current or future detectors. Light, milli-magnetic monopoles, if they exist, could be pair-produced non-perturbatively in the extreme magnetic fields of neutron stars, such as magnetars. This non-perturbative production furnishes a new, direct dissipative mechanism for the neutron star magnetic fields. Through their consequent effect on the magnetic-field-induced quadrupole ellipticity, they may then potentially leave imprints in the early stage continuous

**gravitational**

**wave**emissions. We speculate on this possibility in the present study, by considering some of the relevant physics and taking a very simplified toy model of a magnetar as the prototypical system. Preliminary indications are that new-born millisecond magnetars could be promising candidates to look for such imprints. Deviations from conventional evolution, and comparatively abrupt features in the early stage

**gravitational**waveforms, distinct from other astrophysical contributions, could be distinguishable signatures for these exotic monopole states.

9/10 relevant

arXiv

Fakeons and microcausality: light cones, **gravitational** **waves** and the
Hubble constant

**gravitational**

**waves**. Expand abstract.

**gravity**as an ultraviolet complete theory, by renouncing causality at very small distances. We investigate whether the violation of microcausality can be amplified or detected in the most common settings. We show that it is actually short range for all practical purposes. Due to our experimental limitations, the violation does not propagate along the light cones or by means of

**gravitational**

**waves**. In some cases, the universe even conspires to make the effect disappear. For example, the positivity of the Hubble constant appears to be responsible for the direction of time in the early universe.

8/10 relevant

arXiv