Lecture (Video)
Main Content
Black Holes and the EHT
- A black hole is a vacuum spacetime with its mass concentrated in an infinitesimally small region at the center
- Strong gravitational field that nothing, not even light, can escape beyond its event horizon
- Scientists have been studying black holes through various indirect ways
- The project was launched in 2009 and received significant funding from multiple agencies worldwide
- Head of EHT then was Sheperd S. Doeleman
- 8 ground based radio telescopes in 2017, 11 in 2018-2020
- Apart from black hole images, also provides information about accretion disks and relativistic jets
How Does the EHT Work?
- VLBI method that uses multiple telescopes across the globe that act as one big telescope using interferometry
- Each telescope collects radio waves from the event horizon and sends it as an electronic signal to the other telescopes. Astronomers turn the data into what the black hole would look like if our eyes could see in radio wavelengths.
- Use precise atomic clocks to accurately record when telescopes receive signals
- Observes at millimeter wavelength, which make it difficult for the data to process, but give a better resolution of 20 micro-arcseconds
Photos made from separate telescopes are put together to create a more detailed image.
Effort of the Scientists in EHT Project
- the EHT had their data of Sagittarius collected in 2017, but released the final photo in 2022.
- Method: interferometry, measurement method using the phenomenon of interference of waves (usually light, radio or sound waves) to get precise measurements forlength and time.
- Team record the every single bit on themselves and physically transport to the MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy for processing.