LIGO makes history again! Discovered the most distant black hole merger from Earth so far
According to the website of the American Physicists Organization, an international team of scientists recently discovered the gravitational waves generated by the largest black hole merger event to date and three other black hole merger events by analyzing data obtained by Advanced LIGO. The largest black hole merger formed a new black hole about 80 times the size of the sun, which is also the black hole merger farthest from the earth.
Recently, a team led by Susan Scott, head of the General Relativity and Data Analysis Group at the Australian National University (ANU), detected that the largest black hole merger to date occurred on July 29, 2017, about 9 billion light-years away from us. Scott said: "In addition, of all the observed black hole mergers, this one has the fastest rotation speed and is the farthest from the Earth." The other three black hole mergers occurred between August 9 and 23, 2017, at a distance of 3 billion to 6 billion light-years from the Earth, and the size of the black holes produced was 56 to 66 times that of the sun.
Image source: Internet
Researchers plan to continuously improve gravitational wave detectors so that they can further discover catastrophic events in more distant deep space. In fact , since the end of the second observation run in August 2017, scientists have been upgrading LIGO and Europe's Virgo gravitational wave detectors to make them more sensitive. Scott said: "This means that in the third observation run starting early next year, we will be able to detect events in more distant space and discover gravitational waves from new unknown sources in the universe."
How much do you know about LIGO, the most accurate detection instrument?
LIGO, Laser Interferometer Gravitational-Wave Observatory, means Laser Interferometer Gravitational-Wave Observatory in Chinese. The LIGO system has two jointly operated devices, one in Hanford, Washington, and the other in Livingston, Louisiana. Since gravitational waves do not leave clues on the electromagnetic spectrum and cannot be seen, the main goal of LIGO is to "listen" to the sound of the universe and obtain evidence of the existence of gravitational waves.
Image source: Internet
Image source: Internet
Image source: Internet
Each LIGO device emits a laser in an ultra-high vacuum chamber, splits the laser in half, and sends the two beams down two perpendicular 2.5-mile-long laser arms, which are then reflected back by mirrors at the ends of the arms.
Image source: Internet
Image source: Internet
When a gravitational wave passes, spacetime in this region changes, causing a tiny relative motion between the two laser arms, a tiny change on the order of one ten-thousandth of a proton's diameter. This changes the relative phase of the returning light that enters the receiving optical system, releasing the light to the optical sensor, creating a measurable signal or noise.
Image source: Internet
LIGO's equipment is the most sophisticated instrument in human history. For example, if you gather all the sand from all the beaches on Earth and measure it with LIGO, if a grain of sand moves, LIGO will be able to detect it. This is LIGO, which has achieved such incredible precision that when it directly detected gravitational waves, human understanding of the universe also entered a new stage.
LIGO，ADI inside
Scott Wurcer is a design expert in the field of precision amplifiers at ADI. The chips he designs are used in precision products in various industries. Wurcer once said that the customer product he is most proud of is a scientific research project - LIGO.
LIGO uses a large number of ADI's integrated technologies. These technologies all reflect ADI's commitment to precision technology - meeting the current requirements for precision indicators and promoting innovation in the field of precision engineering and the realization of key applications in the future.
In addition to predicting and compensating for all other possible sources of environmental noise, LIGO also requires that their laser amplitude must remain ultra-stable, with amplitude variations no greater than 2x10-9 at about 100 Hz carrier displacement . This is impossible to do directly with the laser, and the LIGO team needs to use a + feedback system to measure the light output and control the amplitude. This requires an ultra-low noise amplifier with specific performance. The LIGO scientific team conducted an extensive review to select the best solution, and ultimately, they chose ADI's AD797 operational amplifier .
To stabilize the laser frequency, the LIGO team uses ADI’s AD590 high-precision temperature sensor to measure the average temperature of the glass vacuum chamber that houses the laser.
While the raw output of the laser is standard, it quickly increases to thousands of watts within the resonant cavity of the laser arm. This generates enough power to create acoustic resonances in the glass mirrors, so LIGO uses ADA4700 high-voltage op amps to drive electrostatic actuators that actively damp the mirrors and keep them in line.
Another ADI device, the AD736 RMS-to-DC converter, is used to measure the energy delivered to the solenoids that drive LIGO’s mirror suspension system and accomplish any required tilt, pitch, and yaw.
Finally, let's take a look at LIGO's introduction by RICH ABBOTT, the chief designer of LIGO's analog circuits.