[ad_1]
In February 2016, scientists at the Gravitational Wave Observatory (LIGO), a laser interferometer, announced the first-ever detection of gravitational waves (GW). Since then, many events have been detected, allowing a better understanding of a cosmic phenomenon predicted more than a century ago by Einstein's theory of general relativity.
A little over a year ago, LIGO went offline to allow the upgrade of its instruments, which would allow detections to be done "weekly or even more often". After performing the upgrades on April 1st, the observatory is put back online and performed as planned, detecting two likely gravitational wave events in the space of two weeks.
LIGO announced April 8 the first of two new GW events, followed by a second announcement on April 12. The signals were detected through the collaboration of three facilities between LIGO and the Observatory of the Virgin in Italy, and it is believed that both were the result of the merger of two black holes.
Thanks to the improvements made to LIGO and Virgo, this scientific collaboration has increased the sensitivity of its instruments by about 40%. For its third round of observation (dubbed O3), the astronomical community has also benefited from a new public alert system, in which the LIGO team sends alerts as soon as detections are made so that observatories around the world can direct their telescopes to the source.
By observing the source in different wavelengths (optical, X-ray, ultraviolet, radio, etc.), scientists hope to learn more about the causes of GW events and the dynamics behind them. For these latest researches, a team of scientists from Penn State University – led by Chad Hanna, an associate professor of physics, astronomy and astrophysics – played a pivotal role.
As Cody Messick, PhD physics graduate student and member of the LIGO team explains:
"Penn State is part of a small team of LIGO scientists who analyze data almost in real time. We constantly compare the data to hundreds of thousands of possible gravitational waves and download the important candidates as quickly as possible to a database. Although several different teams all perform similar analyzes, the analysis conducted by the Penn State team charged the candidates made public for these two detections. "
Over the past nine months, Messick has been responsible for ensuring that newly downloaded GW candidates contain information from all detectors operating at the time of detection. This helps astronomers locate the signals by narrowing the expected sky zone from which the signal should come.
LIGO's public alerts also include a sky map indicating the possible position of the source in the sky, the time of the event and the type of event alleged. LIGO also stated that in the future, announcements of candidate events would be followed by more detailed information once they have had the opportunity to review and review them. correctly.
Ryan Magee, Penn State physics graduate student and member of the LIGO team, said:
"These are near real-time gravitational wave detections produced by two likely colliding black holes. We detected the first signal about 20 seconds after it arrived on Earth. We can set up automatic alerts to get phone calls and SMS when an important candidate is identified. I thought I was getting a spam phone call early!
Until now, astronomers have deduced that GW events could result from the fusion of binary black holes, a merger between a black hole and a neutron star, or a merger. Binary neutron stars. Each of these events produces gravitational waves with very different signals, allowing astronomers to determine the cause.
In this case, it is thought that the events are the result of the merging of binary black holes, which will be tested with follow-up observations in the weeks and months to come. Surabhi Sachdev, Eberly postdoctoral researcher in Physics at Penn State and a member of the LIGO team, explained the importance of these latest events:
"This is the first LIGO sighting to be made public immediately in an automated way. This is the new LIGO policy from this observation cycle. Events are instantly made public automatically. After human verification, a confirmation or a retraction is issued in a few hours. "
With the increased sensitivity of their detectors, the LIGO team not only hopes to make more detections, but also to detect a wider variety of signals. Up to now, events have been detected, resulting from the fusion of two black holes or neutron stars. The team should be able to detect in the near future a signal resulting from the fusion of a black hole and a neutron star.
Whatever the shape of the next events, you can expect to hear about it! The public can track public alerts at https://gracedb.ligo.org/latest/ or download the iPhone Gravitational Wave Events iPhone alarm application.
Further reading: PSU, LIGO Caltech
[ad_2]
Source link