It all began with the discovery of Sagittarius A, a persistent radio source located at the Galactic Center of the Milky Way. The realization that the hypervelocity jets of the SMBHs are at the center of most galaxies was accompanied by the discovery. Scientists have been trying to get a better look at Sag A and its surroundings to learn more about the role SMBHs play in the formation and evolution of our galaxy.
The goal of the GRAVITY collaboration has been to study the core of the Milky Way for the past thirty years. The team used the Very Large Telescope Interferometer to obtain the deepest and most accurate images to date of the region. These observations led to the most precise measurement of the black hole's mass and the discovery of a never-before-seen star.
Scientists from the Max Planck Institute for Extraterrestrial Physics are part of the GRAVITY collaboration. The GRAVITY adaptive optics instrument was developed for the VLTI.
Interferometry is a technique used to combine the light of all the telescopes at the Very Large Telescope. Reinhard Genzel, a member of the GRAVITY collaboration, was awarded a Nobel Prize in 2020 for his research on Sagittarius A*. He said in a press release that this latest research offers new insight into the many questions that have been asked about the SMBH.
How big is the black hole at the center of the Milky Way? Does it move? Einstein's general theory of relativity states that stars around it behave the same. The best way to answer these questions is to follow stars on their way to the black hole. We can do that to a higher degree than ever before.
Information Field Theory is a machine-learning technique used by the collaboration team. The simulation was used to compare the actual results to the simulation results. They were able to get high-resolution images of Sag A* and the Galactic Center that were 20 times sharper than any made by the individual VLT telescopes alone.
The team used data from two former VLT instruments, the NACO and SINFONI, as well as data from the Keck Observatory and NOIRLab's Gemini Observatory in the US. The team used these instruments to make precise measurements of the stars that Sag A* was passing by.
The GRAVITY instrument on the VLTI captured images of stars very close to the black hole at the center of the Milky Way. Credit:GRAVITY collaboration
S29 holds the record for being the closest and speediest approach to Sag A* ever observed. The star passed within 8 billion km of the Earth in late May of 2021, and achieved a speed of 8,740 km per second. They found a new star that was previously undetected, demonstrating the power and effectiveness of their observations.
The VLTI gives us this incredible spatial resolution, and with the new images, we reach deeper than ever before. We are amazed by their amount of detail and the number of stars they reveal around the black hole.
Genzel said that following stars around Sagittarius A* allows us to precisely probe the gravity of the black hole, to test General Relativity, and to determine the properties of the black hole. Albert Einstein proposed General Relativity in 1916. Scientists have sought opportunities to test the theory under the most extreme conditions.
The stars follow paths predicted by General Relativity perfectly according to the latest observations. The team was able to estimate the black hole's mass at 4.3 million Solar masses, the most precise estimate yet. The collaboration team was able to fine-tune the distance to Sagittarius A* because of the precise nature of the images and measurements.
When the first light of the decade arrives, the ELT will be the biggest eye on the sky. The credit is given to the ESO.
Thirty years of observations of our galactic center have been expanded by these latest results. The first paper details how the observations of the Sag A* stars help determine the SMBH's mass.
The second paper describes a new analysis technique that the team developed to obtain the deepest and sharpest images of the region surrounding Sag A. The GRAVITY instrument will be upgraded with GRAVITY+ in the coming years, which will allow further observations of the Galactic Center. This upgrade will push the sensitivity of the VLTI even further and show fainter stars that are closer to Sag A.
The team wants to eventually find stars that are so close to Sag A* that they are subject to the effects of the black hole's rotation. The ELT is being built in the Atacama Desert in northern Chile. The ELT will be the most powerful observatory in the world once it is finished. The Giant Magellan Telescope is scheduled to be finished by the year 2025.
Next- generation telescopes will be headed to space in the coming years, like the James Webb Space Telescope that will be launching from the European Spaceport in French Guiana tomorrow! The Nancy Grace Roman Space Telescope (RST) will join the JWST when the ELT begins to gather light. astrophysicists are looking to the coming years with great excitement.
Further reading includes Astronomy and A&A.
