高能暂现源 · 每日文献综述

In dynamically formed binaries, the spins of the black holes tend to be misaligned with the system's orbital angular momentum. This causes the spins to precess and leads to an asymmetric emission of gravitational waves. The resulting gravitational-wave multipole asymmetries directly source the recoil of the remnant black hole and are the critical element in fully describing precession. Recoil and precession are of significant astrophysical importance, but multipole asymmetries contribute only minimally to the overall signal strength. Consequently, most current gravitational-wave models either do not incorporate asymmetries at all, or only consider the dominant ones. Here we highlight the importance of subdominant multipole asymmetries for an accurate recoil velocity calculation and discuss their detectability with third generation detectors. Neglecting subdominant asymmetries leads to velocity differences of up to <inline-formula><mml:math><mml:mrow><mml:mn>210</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>km</mml:mi><mml:mo>/</mml:mo><mml:mi>s</mml:mi></mml:mrow></mml:math></inline-formula> and can, in particular, introduce systematic biases in the inference of masses and the spin geometry. We further discuss universal characteristics of subdominant multipole asymmetries in order to prepare the ground for potential future asymmetry models. In the inspiral regime, the average antisymmetric frequencies can be described by a multiple of the orbital frequency. During ringdown, however, they become equal to their corresponding symmetric frequencies.

The phase evolution of gravitational waves encodes critical information about the orbital dynamics of binary systems. In this work, we test the robustness of parametrized tests against unmodeled deviations from general relativity. We demonstrate that these parametrized tests are flexible and sensitive in detecting generic deviations in the waveform using the Cutler-Vallisneri bias formalism. This universality arises from examining the inherent geometry of the waveform signal and understanding how biases manifest. We show how Bayes factors are governed by the intrinsic geometry of the waveform signal manifold when parametrized tests are used to approximate generic violations of GR. We use the singular value decomposition to propose templates that are orthogonal to parametrized tests, identifying degeneracies and enhancing the detection of potential deviations. More broadly, the geometric framework developed here clarifies—at a fundamental level—how subtle waveform effects (including orbital eccentricity, spin precession, waveform systematics, and instrumental glitches) can mimic one another in data, and when they are intrinsically distinguishable.

Minimal electroweak dark matter models are compelling due to their simplicity, though calculations of their freeze-out abundance are complicated by nonperturbative effects due to Sommerfeld enhancement and bound-state formation. It has been shown that all individual multiplet scenarios beyond the doublet lead to direct-detection signals above the neutrino floor and thus within the reach of next-generation experiments. If no signals are found, would minimal dark matter be excluded? Yes for the simplest models, but it has been unknown for the important extension of two multiplets coupled by Higgs interactions (Higgs-coupled minimal dark matter). We present a generalized framework for calculating nonperturbative effects for such models that also covers the case of individual multiplets. In this framework, we calculate nonperturbative effects on freeze-out as well as the prospects for direct detection, correcting shortcomings and omissions in the literature. Importantly, for the mixed Majorana (odd) and Dirac (even) multiplet combination <inline-formula><mml:math><mml:mn>3</mml:mn><mml:mi>M</mml:mi><mml:mn>2</mml:mn><mml:mi>D</mml:mi></mml:math></inline-formula> (and marginally the <inline-formula><mml:math><mml:mn>5</mml:mn><mml:mi>M</mml:mi><mml:mn>4</mml:mn><mml:mi>D</mml:mi></mml:math></inline-formula>), we find that the predicted direct-detection signals can extend below the neutrino floor. Fully testing minimal dark matter will thus require more than direct-detection experiments.