Smile Black Hole – You’re on Camera (Part Two)

Who wouldn't dream of seeing a black hole up close (but not too close)? In this second article we will take a look at the advances in technology that allow us to view the black hole at the center of the Milky Way.

First, we should understand the obstacles. As we are situated in a disk galaxy, there are large numbers of stars situated exactly in between us and the Galaxy's center. This introduces a kind of 'light pollution' in the form of starlight which interferes with our ability to see faint emission emanating from the accretion disk surrounding the black hole.

This is analogous to watching a friend holding a piercingly-bright flash light on a dark path. You see the flashlight but not the physical features of your friend who you know must be holding the light.

By choosing the color The Milky Way's central supermassive black hole carefully, we are able to view the black hole at a color in which the stars weakly shine. This color is in the radio. Even with this color advantage, the emission from the material falling into the black hole is still very faint, requiring high sensitivity. Sensitivity for radio receivers scales with bandwidth. By recent advances in digital electronics we have been able to develop data collection at high bandwiths which will make this a 21st century experiment.

Secondly, as we discussed last time, black holes are physically small. We approach the spatial resolution that we need by combining or 'phasing up' the light incident on many telescopes spread out across the whole world. By phasing up the signal we achieve a resolution equivalent to that of the Earth. In other words, we use telescopes worldwide in unison as an interferometer to operate a kind of 'telescope' with an aperture the size of Earth.

Finally, these enormous interferometers have higher spatial resolution at higher frequencies. Technology continues to develop in the direction of enabling observations at a wavelength of 1 mm and even in the sub-millimeter. At the end of the day (or perhaps of this decade), we will be able to take pictures of the enigmatic monster at the Galactic center. Theorists are working hard to predict what we will see in this grand experiment called the Event Horizon Telescope.

Dr. Brenda Frye

About Dr. Brenda Frye

Brenda L. Frye is an observational cosmologist at the Department of Astronomy/Steward Observatory, University of Arizona. She earned her Ph. D. in Astrophysics from the University of California at Berkeley, assisted by a National Science Foundation Graduate Research Fellowship.

Her thesis work involved measuring the concentration of the total mass of visible plus dark matter in the fields of massive galaxy clusters, a program requiring the use of some of the largest telescopes in the world.

Moving a mile from her Ph. D. institution, she assumed a postdoctoral position with the Supernova Cosmology Project at Lawrence Berkeley National Laboratory under the direction of Professor Saul Permutter.

She then treked across the country to take a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship and a Princeton Council on Sciences and Technology Fellowship both at Princeton University.

Moving further east, she became a Lecturer in Physics at Dublin City University in Dublin, Ireland, where a number of European collaborations were formed.

From there she crossed back across the pond to the west coast of the U. S. to become a tenure-track Assistant Professor of Physics at the University of San Francisco.

Her travels have now landed her at her Alma Mater in Tucson, where she teaches and does research. The aims of her research continue to be to use gravitational telescopes in space as 'lenses' to study the properties of dark matter and those of distant galaxies back to when the universe was <900 million years old.

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