According to a new study, an independent reanalysis of the Event Horizon Telescope (EHT) observational data for the centre of the elliptical galaxy M87 produced images with different features. This study is part of the modern scientific research process, in which observational data and analysis methods are made available to the public and reviewed and discussed by various communities of researchers in order to produce more credible results.
The Event Horizon Telescope’s radio observational data for the centre of the elliptical galaxy M87, as well as the methods used to analyse the data, were made available to the public worldwide in April 2017. Researchers who were not involved in the EHT independently reanalyzed these data and methods, validating the EHT’s findings. In fact, several teams have published detailed reanalysis results in peer-reviewed journals.
Makoto Miyoshi (Assistant Professor at NAOJ), Yoshiaki Kato (Contract Researcher at RIKEN at the time of the study), and Junichiro Makino (Professor at Kobe University) led a research team that reanalyzed the M87 data using standard tools and investigated the data’s nature. Instead of the ring structure seen by the EHT, the images show a “core” at the galactic centre, as well as an astrophysical jet extending from the core and “knots” that appear to be part of the jet.
Many supermassive black holes emit astrophysical jets; the one extending from the centre of M87 has been studied on numerous occasions for more than a century. The research team believes that their analysis has resolved the base of this jet. The team notes that the 40-micro-arcsecond (1/25,000th of an arcsecond) ring structure seen in the EHT image is likely due to a lack of sufficient data to resolve 40 micro-arcsecond structures, as compared to data for other sizes, due to the fewer telescopes involved in the EHT observations at the time.
This study, published in The Astrophysical Journal, demonstrates the significance of the sensible, normal process that modern science should use, with independent research teams reviewing observational data and analysis methods. More data reanalysis, method testing, and planned follow-up observations are expected to provide more credible insights into M87’s core and the structure of the jet blasting out from the galactic centre.