The Virgo and LIGO gravitational wave detectors recorded 39 events between April and October 2019. These large numbers of observations correspond to the collision of black holes or neutron stars, opening the door to new research on astrophysical objects and basic physics.
After the third observation and months of analysis, scientific cooperation Ligao (There are two detectors in the U.S.) and Virgo (The other is in Europe) has released a new updated catalog of gravitational wave detection.
The new directory is called GWTC-2, Continue with the previous one, which includes the first two observation periods detected (GWTC-1, released in November 2018), and contains 39 new signals from 39 collisions. Black hole or neutron star Testing conducted between April 1st and October 1st, 2019 showed that the number of confirmed tests has more than tripled.
The new system includes some of the most interesting systems observed so far, and allows new qualitative and quantitative studies of astrophysical populations and basic physics.
A total of four scientific articles will be published at the same time, introducing New resource catalog,Correct The significance of astrophysics, Relativity test General and looking for gravitational waves Related to gamma-ray bursts (Gamma Ray Burst (English)), but no other signals are detected. The abstract can also be obtained from the following URL: LIGO website.
Quantum Compression Technology
Thanks to the significant improvement of the observation instrument compared to the previous observation period, the number of detections is likely to increase significantly. These improvements include increased laser power, improved mirrors, and most notably the use of quantum compression technology (Quantum compression).
This can increase the detectable signal by about 60%. In addition, compared with the past, the detector has a duty cycle of 75%, compared to 60% in the past, so it can be operated more frequently than in the past.
Researchers believe that all these new signals can improve our understanding of the number of black holes and neutron stars in the universe. By analyzing the entire binary merging group of black holes at the same time, the celestial information extracted from the analysis is maximized.
The conclusion drawn from them is that the mass distribution of a black hole does not follow a simple electric potential distribution. By measuring deviations from this underlying law, it will be possible to understand the formation of these black holes due to the death of stars or previous collisions.
Treating the entire population as a set, you can also perform more reliable measurements on attributes that are difficult to measure, such as The spin or angular momentum of a black hole. The spin of some black holes in the fusion process is out of balance with their angular orbital momentum, which allows us to show the mechanism of the formation of these binary stars.
Test Einstein’s Theory of Relativity
Compared with the past, many signals in the updated catalog can also be used to test Einstein’s theory of gravity, and are more and better. This can be done by comparing the data with theoretical predictions, thereby limiting possible deviations from the predictions.
The results of multiple signals have been combined using new statistical methods to obtain the best limit of gravity properties in the strong and highly dynamic black hole merger mechanism so far.
In the new catalog, LIGO and Virgo can also directly study the properties of the remaining objects produced by the fusion: by measuring the vibrations of these objects, and excluding the main signal LIGO and Virgo, the possible “echo” has been confirmed, the behavior of the remnants Just as expected in Einstein’s theory.
More results and observations
The results shown in the new catalog only correspond to the first six months of the third observation period of LIGO and Virgo. The results of the remaining five months are being analyzed.
At the same time, LIGO and Virgo instruments are being improved to prepare for the use of Japan’s GRAGRA detector in the fourth observation period. According to the researchers, many interesting discoveries have yet to come.
research team gravity From University of Balearic Islands (UIB) It has contributed to these results in various ways.Group leader Alicia sintes, Served as a gamma-ray outbreak (ggamma ray burst).
In addition, with the following efforts, the group has also contributed to the development of a theoretical model that is used to decode the attributes of the astrophysics source Sascha Husa, And actively participate in the parameter estimation of some new events.
PhD student Pep Covas (Now a doctor) and Rodrigo Tenorio The Hanford detector has worked for three months. Each observer characterizes the detector noise during this observation period. This is an important factor in distinguishing between astrophysics signals and celestial signals caused by ground noise. Work and David Kittle Coordinated release summaries of four new publications.
At the same time, the team is very active in 2020 and released a new and efficient binary collision model, which will enable the scientific community to study the complete symphony of gravitational waves, including their different harmonics.
Till now, Signal harmonics Gravitational waveforms are not used routinely. Due to the high computational cost involved, the published catalogs limit systematic research on the effects of these harmonics.
The model proposed by the UIB team during 2020, with a total of 6 publications (2 of which are still in the peer review process), will allow the harmonics of all events detected in the catalog to be studied in a systematic and effective manner. And future updates.
The first research using the new model has allowed the results of the GW190412 event (originally published in April) to be refined in a UIB Group publication, and also proposed a possible explanation for the larger-scale black hole merger until the black hole merger was discovered . Date, GW190521 (originally released in September). This final work was done by a team from the Albert Einstein Institute in Germany.
Sascha Husa pointed out: “For everyone, this is an extraordinary year for our group, with ups and downs, and regardless of the situation of LIGO cooperation, we have published the most of all scientific papers over the years.”
He added: “Now that the catalog has been published, I feel relieved about it-he added, but I have to say more, because we have obtained nearly 10 million hours of computing time through the Spanish Supercomputer Network (RES), This allowed us to continue. I worked at the same level for another four months, so I was able to study the most interesting event candidates in the next gravitational wave catalog, especially thanks to being able to cooperate with the Mare Nostrum supercomputer (the fastest of the computers). One of the fastest computers) work together. Europe.”
“It is difficult for a team in Mallorca to contribute to a scientific endeavour of this magnitude, and it is very difficult to cooperate and compete with institutions such as the California Institute of Technology, the Massachusetts Institute of Technology or the Max Planck Institute in Germany. But we are optimistic that Spain recognizes the importance of R + D + i and increases investment in a knowledge-based economy,” Alicia Sines pointed out.
As a member of the LIGO or Virgo collaboration, a total of 5 teams in Spain have contributed to gravity wave astronomy, ranging from theoretical modeling and data analysis of astronomical resources to improving the sensitivity of detectors in current and future observation periods.
Part of the LIGO scientific collaboration is composed of the University of Balearic Islands (UIB) and the Galician Institute of High Energy Physics (IGFAE) of the University of Santiago de Compostela (USC). The University of Valencia (UV), the Institute of Universe Sciences of the University of Barcelona (ICCUB) and the Fisica de Alter Institute for Energy in Barcelona (IFAE) are members of the Virgo.