The First Black Hole Picture: A Scientific Beginning
Ever since Einstein published his theory of general relativity over one hundred years ago, scientists have been attempting to learn more about one of his theory’s great implications: black holes. These infinitely dense, yet somehow infinitely small, formations with a gravitational force so strong that no light can escape have captivated researchers and common people alike. Despite their continued existence in pop culture, it was not previously known what a black hole looks like. If no light can escape it, it seems logical that it would be difficult for a telescope to find. However, a collaboration between many research groups has allowed for the creation of six papers that document exactly how the team captured the first picture of a black hole.
It is well-known that black holes are part of the life cycle of many large stars. However, this is just one type of black hole. There are three main types of black holes; in order of increasing size they are primordial, stellar, and supermassive. It is believed that primordial black holes formed during the early time of the universe’s formation. Stellar black holes are the common variety created from the collapse of a supernova. Supermassive black holes are theorized to form when the galaxy they are in is developing. It is also thought that many large galaxies have one of these supermassive black holes in the middle of them. The Milky Way’s central black hole is known as Sagittarius A.
Even though there have been no proper images of black holes until now, there has been no doubt that black holes exist. While they could not previously be seen, it was still possible to observe the effects of a black hole’s vast mass on the stars and other objects drawn into its strong gravitational field. Observing the effects on the star makes it possible to classify and better understand the black hole. With this new imaging technology, researchers will be able to learn even more about the characteristics of black holes.
Capturing an image of a supermassive black hole was an immense effort that required international cooperation. In total, over two hundred individuals in twenty countries from all levels of the field contributed to the project. The creation and use of the Event Horizon Telescope, a series of eight ground-based radio telescopes in six locations, is a testament to the collaborative process used to connect researchers around the world. Together, they can image with a greater sensitivity than was previously possible.
This team published six papers simultaneously as part of the initial report of the successful imaging. The first paper acts as a summary for the overall process that resulted in the imaging of a black hole’s shadow. The other five papers describe the setup for the telescope network, data processing methods for their information, image reconstruction process, analysis using existing models and data on black holes, and making final predictions on the nature of the specific black hole captured based on models.
The picture itself is of the supermassive black hole theorized to be at the center of a galaxy known as M87. It shows the way light bends around the strong gravitational force coming from a black hole. Despite extensive theories and mathematical evidence, this picture is the next step in proving the existence of these black holes and better understanding their features. The team sees its discovery as the beginning of a new aspect of astrophysics research that will allow us to further our knowledge of supermassive black holes.
Pop culture has speculated about how black holes actually ‘look’ for decades, and people have been surprised to see an image that somewhat matches the expectation set by movies and books. However, it is important to remember that this is a previously unproven idea. A similar concept with less important implications was New Horizons taking the first clear pictures of Pluto. While we did have a vague idea of its appearance, advances in technology allowed us to properly see the well-known dwarf planet for the first time. Seeing Pluto may not have created a whole new branch of research, but it does demonstrate the excitement we have for new knowledge and new interesting aspects of space. Being able to better characterize black holes may not affect our daily lives, but it does improve our overall understanding of the universe and the way matter behaves. There is still so much we do not know, and it will be exciting to see what these diverse international teams of researchers can discover as we move forward.
Evan O'Connor and Christian D. Ott 2011 ApJ 730 70
The Event Horizon Telescope Collaboration et al 2019 ApJL875 L1