Never Before Detected Gravitational Wave Template, possible indication of Dark Matter:

[beecee]

https://newatlas.com/physics/gravitational-waves-dark-matter-black-hole/

Never-before-detected gravitational waves hint at dark matter:

A new type of gravitational wave detector running in Western Australia has recorded two rare events that might be signals of dark matter or primordial black holes. These high-frequency gravitational waves are beyond the range of most detectors and have never been recorded before.

Gravitational waves are ripples in the very fabric of spacetime, first predicted by Einstein over a century ago but not directly detected until 2015. In the years since, dozens of detections have been made, mostly by facilities like LIGO, which can detect waves with frequencies between 7 kHz and 30 Hz. That’s in the range for waves produced by cataclysmic events like black holes and neutron stars colliding.

But gravitational waves are also expected to fall outside that range. Two experiments are currently searching for very high frequency waves, which could represent other cosmic events or objects. And now the first batch of data has been returned for one of these experiments, including two detections of particular interest.

The project is run by the ARC Center of Excellence for Dark Matter Particle Physics (CDM) and the University of Western Australia, and it’s based on a unique type of gravitational wave detector, known as a bulk acoustic wave (BAW) resonator.

more at link..................

 

the paper:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.071102

Rare Events Detected with a Bulk Acoustic Wave High Frequency Gravitational Wave Antenna

ABSTRACT: 

This work describes the operation of a high frequency gravitational wave detector based on a cryogenic bulk acoustic wave cavity and reports observation of rare events during 153 days of operation over two separate experimental runs (run 1 and run 2). In both run 1 and run 2, two modes were simultaneously monitored. Across both runs, the third overtone of the fast shear mode (3B) operating at 5.506 MHz was monitored; whereas in run 1, the second mode was chosen to be the fifth overtone of the slow shear mode (5C) operating at 8.392 MHz. However, in run 2, the second mode was selected to be closer in frequency to the first mode; and it was chosen to be the third overtone of the slow shear mode (3C) operating at 4.993 MHz. Two strong events were observed as transients responding to energy deposition within acoustic modes of the cavity. The first event occurred during run 1 on 12 May 2019 (UTC), and it was observed in the 5.506 MHz mode; whereas the second mode at 8.392 MHz observed no event. During run 2, a second event occurred on 27 November 2019 (UTC) and was observed by both modes. Timings of the events were checked against available environmental observations as well as data from other detectors. Various possibilities explaining the origins of the events are discussed.

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Additional GW news....

https://www.ligo.caltech.edu/news/ligo20210817

New material to improve the range of gravitational wave detectors

News Release • August 17, 2021

The ability of the gravitational-wave observatories to study the physics of large-scale events, such as the collision of black holes and neutron stars, is actually limited by physics at the microscopic scale. Specifically, the random molecular thermal motion in the laser interferometer mirrors generates a noise large enough to cover the faintest signals coming from the universe.

Research on improved amorphous materials to be used in higher performance mirrors has been going on for the last two decades, resulting only in marginal improvement with respect to the thermal noise of first-generation detectors.

Our results show that a novel material, a mixture of titanium oxide and germanium oxide, would allow reduction in the thermal noise coming from mirror coatings by a factor of two, the largest improvement ever measured, paving the way to the next generation of gravitational wave detectors.

These new mirror coatings, together with other planned upgrades, will nearly double the observatories’ reach, allowing probing a volume of the universe almost 8 times larger than what is possible today. We expect to be able to increase the detection rate of gravitational waves from once a week to once a day or more.

Published in Phys. Rev. Lett. 127, 071101 (2021).

the paper:

https://arxiv.org/abs/2108.04954

Low mechanical loss TiO2:GeO2 coatings for reduced thermal noise in Gravitational Wave Interferometers:

The sensitivity of current and planned gravitational wave interferometric detectors is limited, in the most critical frequency region around 100 Hz, by a combination of quantum noise and thermal noise. The latter is dominated by Brownian noise: thermal motion originating from the elastic energy dissipation in the dielectric coatings used in the interferometer mirrors. The energy dissipation is a material property characterized by the mechanical loss angle. We have identified mixtures of titanium dioxide (TiO2) and germanium dioxide (GeO2) that show internal dissipations at a level of 1 ×10−4, low enough to provide almost a factor of two improvement on the level of Brownian noise with respect to the state-of-the-art materials. We show that by using a mixture of 44% TiO2 and 56% GeO2 in the high refractive index layers of the interferometer mirrors, it would be possible to achieve a thermal noise level in line with the design requirements. These results are a crucial step forward to produce the mirrors needed to meet the thermal noise requirements for the planned upgrades of the Advanced LIGO and Virgo detectors.

Edited August 25, 2021 by beecee