It’s a number that statistically represents how strong the result is in the data basically. As far as I understand it, with astronomy the typical sigma value expected is 3
By saying 1 sigma, they are basically saying tgat are 68% confident in the results. As you increase the sigma, your confidence in the results increases. Here is a site that goes into more in depth explanation:
https://news.mit.edu/2012/explained-sigma-0209#
What does 1 sigma mean?
It’s a number that statistically represents how strong the result is in the data basically. As far as I understand it, with astronomy the typical sigma value expected is 3
By saying 1 sigma, they are basically saying tgat are 68% confident in the results. As you increase the sigma, your confidence in the results increases. Here is a site that goes into more in depth explanation: https://news.mit.edu/2012/explained-sigma-0209#