• Energy Research

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses $\gtrsim 30\, \text{M}_\odot$, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO/Virgo band for stochastic backgrounds (near 25 Hz), we predict $��_\text{GW}(f=25 Hz) = 1.1_{-0.9}^{+2.7} \times 10^{-9}$ with 90\% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO/Virgo detectors operating at their projected final sensitivity. 12 pages, 3 figures

Silicon resonators are widely used in a large class of applications including sensing and actuation, signal processing and energy harvesting. Very often, their application as sensors requires the deposition of metallic thin films or dielectric coatings, to set the electrical conductivity, the optical coupling, or other physical-chemical properties of the device. Invariably coatings degrade the quality factor (Q) of resonance by increasing the amount of energy dissipated during vibration. In this paper, we show a class of resonators used for the investigation of thermal noise statistical properties in non-thermodynamic equilibrium. Design strategies to preserve the silicon Q-factor are discussed.