The press around the planet portrayed the historic moment as the image of a dark circle in the middle of a glowing disk. An unpublished reproduction that came from some 50 million light-years from Earth and was captured in the center of the galaxy M87.
“Just the week before the announcement was made, we were working at the OSF for the VLBI (Very Large Baseline Interferometry) campaign for that year. I remember that there was a lot of secrecy about the announcement, and not even those of us on the team were allowed to see a preview of the image that was going to be shown days later,” says David.
Four years after that milestone in the history of world astronomy, David recalls that “the announcement was impressive, with all the public and press interest that had gathered to know the details of this great discovery. It was an intense day, with interviews for many media, and also on social networks. Undoubtedly, a day that will remain engraved in the memory of many”.
A finding that changed the life of Hugo Messias, Operations Astronomer and VLBI Technical Leader at ALMA. “Suddenly, we got all the attention in the world and ended up in the Chilean Senate. In Portugal, this result also got a lot of media attention and I was asked for many interviews, and in the end I received an award from a magazine,” recalls the European astronomer.
“It was one of those moments when you sit in the right place at the right time to observe a group of hundreds of people reaching a great milestone in science. Being involved gives it an even better flavor and it will always be an important memory in my life.”
While the historic moment is still on ALMA’s retina, our observatory is already working on a series of projects with VLBI technology, as was done in 2019.
A system that allows us to observe one or several celestial objects with the help of a large number of radio telescopes deployed at various points on the planet, and then process the data together.
“More and more stations are being added and this will allow for better image quality. For example, it will allow us to better study the jet present in M87”, explains Hugo.
During April ALMA will start running VLBI observations in Band 7 for the first time. By observing at a higher frequency the array will be able to obtain greater detail.
Hugo also tells us about the long term: “Later on we are talking about projects not yet confirmed, such as a satellite with which joint VLBI observations will be made to improve the spatial resolution of the image”.
Detecting gas motion: the near future
ALMA is constantly improving the technical capabilities of VLBI in order to increase the scientific impact of its observations. “Since the current Cycle 9, the range of frequencies available for observing has been expanding. Originally only Bands 3 and 6 could be used for continuum emission detection, but in Cycle 9 it was extended to Band 7, i.e. higher frequencies, and also allowed us to observe spectral lines in Band 3. The important thing here is that it will allow us to detect gas motion”, says David.
For Cycle 10, a wider range of frequencies will be offered, adding Band 1 when available. In addition, spectral lines will be observed using Bands 3, 6 and 7. According to David, this improvement in our capabilities will allow expert astronomers “to make unprecedented observations, improving our understanding of such intriguing objects as black holes, among others.”
The team is just now verifying the VLBI system at the OSF, led by MIT astronomer Geoff Crew, in preparation for the new observations that begin tomorrow.
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