The Event Horizon Telescope
Due to the immense gravity of black holes, imaging them directly is impossible with current technology. With gravity so strong that not even light can escape, what do you image? So far we’ve been able to detect the existence of black holes by measuring the dust, gas and other objects such as stars by how these objects move around a black hole. Now, scientists are testing a method where we will actually be imaging the shadow of the black hole. This shadow has been defined by the moment the event horizon meets with protons that were able to escape. That very instant where its only a one-way road between the black hole and the open space around it. This “shadow” is not measured in visible light however, its measured instead by radio frequency. We’ll be monitoring the closest black hole to us Earthlings in our own home galaxy the Milky Way. Our black hole is identified by Sagittarius A* (Sgr A*) and it sits comfortably 26,000 light years away from us. Since we can’t directly observe the region near Sagittarius A* in visible light (due to the crowded region of stars and gas), we’ll be capturing this shadow in the radio spectrum. This project is called Black Hole Cam (blackholecam) and is a project funded in the EU with the assistance of scientists around the globe.
The Black Hole Cam is not just one “camera”. Its actually a telescope (radio). Well, several telescopes from around the world. These telescopes collectively make up our blackholecam called the Event Horizon Telescope. These telescopes are positioned around the world in a manner that essentially gives us an Earth-sized radio telescope. The size of Sgr A* is roughly half the distance between the Earth and the Sun. That’s pretty big. But, we’re also 26,000 light years away from it. This would be like imaging an apple on Earth from the Moon. The distance with which Sgr A* is located from Earth, coupled with it’s size, makes it a very small target to monitor. The Event Horizon Telescope “network”, gives us an Earth sized telescope to equip us with the viewing power we need to see this object in the detail we’re looking to achieve.
The method described above is known as Very Long Baseline Interferometry Imaging (VLBI).
The data collected from these telescopes will be written to large disks and shipped to data analysis facilities. Here, the data will be analyzed by supercomputers and reconstructed to form the images. The data we collect may finally answer our understanding of the laws of gravity. Furthermore, which law is correct? One we are most familiar with is Einstein’s theory of general relativity. There are a few others, and with the data we collect from this project, we may finally be able to definitively answer which one is correct. Maybe none? I don’t know. But its all damn interesting! Here are some links that I was reading on that you can continue your reading: