Allegedly faulty image of Sagittarius A*: EHT clearly rejects criticism
After a Japanese team claimed that the image of the Milky Way's central black hole was "flawed", the EHT reacted decisively.
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(Image: EHT Collaboration)
Those responsible for the Event Horizon Telescope (EHT) have firmly rejected the criticism of the first image of the Milky Way's central black hole and speak of several errors in the research work. The research team of Makoto Miyoshi responsible for the image had ignored the variability of the black hole in its image processing, merely calculated a new image, worked too much towards the assumed shape and ignored its own biases, the research community summarized in a blog post. That is why they continue to stand by their own image of Sagittarius A*.
Criticism comprehensively rejected
With the statement, in which the four main points of criticism and several false claims are listed, those responsible at EHT are responding to a research paper that appeared in Monthly Notices of the Royal Astronomical Society. In it, Miyoshi's group explained why the historical image of Sagittarius A* is wrong. Because the EHT did not use widely used, traditional methods to evaluate the measurement data, the ring-shaped image was created. However, if these methods are used, a rather elongated structure is created instead, which can be traced back to an enormously fast rotating disc of matter.
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The Event Horizon Telescope is not prepared to let this criticism rest and has responded extensively in its own blog. In addition to the central errors in the research work from Japan, the research community has also identified several false claims. For example, Miyoshi's team stated that the EHT method for calculating the image was untested and unverifiable. This is not true, as it had already been developed for the image of the M87 black hole and subsequently confirmed several times. The research group also claimed that the EHT had not published any raw data. However, they have been online since 2022.
The Event Horizon Telescope (EHT) is a radio telescope network of instruments around the globe, whose combination creates a virtual observatory the size of our home planet. Two of them are located in Europe, the largest being the Atacama Large Millimeter/submillimeter Array (ALMA) of the European Southern Observatory ESO in Chile. Together they have provided the historic images of the supermassive central black holes of the galaxy M87 and the Milky Way. The latter was also regarded as "outstanding visual proof" that the object was indeed the black hole described. Previously, there had been repeated attempts to explain the observations in other ways – , for example with the help of dark matter.
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