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University of Massachusetts Amherst astronomers help create powerful telescope to explore center of galaxy



Wednesday, February 03, 2016
AMHERST — Some questions in science can only be answered by more powerful equipment. So University of Massachusetts Amherst astronomers are working to create one of the most powerful telescopes yet — one the size of the Earth.

How is this possible? Gopal Narayanan, an associate professor in the UMass astronomy department, said readings from multiple telescopes around the world are being synchronized to fill in an Earth-sized readout of the center of the galaxy.

The project is called the Event Horizon Telescope because its purpose is to learn how the laws of physics operate at an event horizon, the point at which light cannot escape the gravitational pull of a black hole.

UMass’ telescope, called the Large Millimeter Telescope, or LMT, is centrally located in Mexico and is one of the most powerful in the group of seven worldwide participating in the project.

“For UMass, this is by far the largest science project we have ever taken part in,” Narayanan said. The telescope costs $130 million, of which UMass has paid one-third, he said.

Inside a black hole, nothing can be observed, but at the event horizon, it is possible to see how energy and matter behave when confronted by so much gravity.

The black hole at the center of our galaxy, the Milky Way, is estimated to be 4 million times as massive as the sun. At the center of a nearby galaxy, Messier 87 in the Virgo Cluster, the black hole is 1,000 times as massive as the Milky Way black hole, and will also be viewed by the Event Horizon Telescope, Narayanan said.

Central question

But despite their enormous mass (weight), black holes take up a relatively tiny amount of space. They are so compact that the Earth would be shrunk down to a square inch and the mass of the sun would be contained in a ball with a radius of less than 2 miles. This makes black holes ideal for studying the central question in physics today: why large bodies like stars and planets seem to obey one set of rules (Einstein’s Theory of Relativity) and small bodies like particles and atoms obey another (quantum mechanics).

“This is the best laboratory for Einstein’s theory of general relativity,” Narayanan said. “You cannot simulate an environment like this. It is a fantastic place to understand physics.”

The problem is that black holes and their event horizons are so small, they have been too hard to see. This is what the Event Horizon Telescope has been created to solve, according to Narayanan.

Less powerful telescopes have been able to see jets of energy shooting out from near the event horizon, but not in any detail. The closest black hole, the one in the center of our own galaxy, is 25,000 light years away.

“They are so far away, we can’t make out any of the details,” said Ron Grosslein, a research engineer in the UMass astronomy department. “You see the power is there, but you can’t watch things move around inside. It’s just a bright spot in the sky.”

Synchronize readings

Individual stations across the globe are pointed in the direction of the black hole and synchronize their readings, using the rotation of the Earth to trace a path of the picture, according to Avery Broderick of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, who is one of the coordinators of the project. The rest of the image is built in a computer, he said.

“You can start studying in detail not just the physics of how black holes grow, but how does the stuff fall into the black hole,” Broderick said. “For the first time, we’re going to be in a position to answer whether Einstein was right about general relativity.”

He said this better understanding of how physics works could lead to new technology, the same way that Einstein’s theories led to the understanding that allowed scientists to develop lasers.

The telescopes involved in the project this spring, mainly known by their acronyms, will be the SMT in Arizona, the SMA in Hawaii, the Pico Veleta telescope in Spain, the APEX in Chile, the JCMT in Hawaii, the ALMA in Chile as well as the UMass LMT.

They gather data once or twice a year, according to Narayanan. Months and even years of coordination are required along with split-second synchronization so that the data can be compiled accurately, he said.

On site in Mexico

The LMT’s first time working with the project was last March, and observations will be conducted again this April. Narayanan and Grosslein are now at the telescope site in Mexico preparing it for use.

Work on the telescope involves building parts at UMass and bringing them to the site in Mexico, but also working on the fly as things inevitably need to be repaired, according to Grosslein.

“We may have found the source of our largest total power instability today,” he wrote in an email last week. “The crew here is very capable, and made us some replacement structural parts. We bolted them on, and we’ll do some tests ... to see if we’ve got it right.”

Conditions at the telescope site, which is 15,000 feet above sea level, can be difficult, according to Grosslein.

“There’s not enough air up there for a late middle-aged engineer,” he said. “We typically get headaches and it is hard to think straight.”

But the high altitude makes the site ideal for observations, even though it is only 5 miles away from another large mountain that happens to be a dormant volcano.

“It can erupt at any time,” Narayanan said.

In addition to being a part of the Event Horizon Telescope project, the LMT has its own individual purpose.

“Our telescope was built to primarily answer one of the most fundamental questions of astronomy: How did the universe form the structure it has right now?” Narayanan said.

Observations have led astronomers to believe the “Big Bang” happened about 13.5 billion years ago, but what remains unexplained is why the universe formed the structures of galaxies it did, he said.

“The whole universe was effectively a point, and when it exploded one could assume it would be uniform and that is not what happened,” he said. “It formed all these fantastic structures.”

Narayanan and his team are pointing their telescope at objects as far away as possible, looking for early galaxies that can give clues about their formation.

He said astronomers can identify earlier galaxies, which are closer to the edge of the expanding universe, through a phenomenon called red shift. The wavelength of light coming off a galaxy lengthens as it moves away, and the more it is lengthened, the faster it is traveling. Astronomers can measure red shift by detecting patterns that elements like hydrogen or helium are known to make when burned in a star.

The light that comes through the Large Millimeter Telescope is not red, however. The telescope captures millimeter wavelength light, a far wider frequency than humans are able to see, because it has an easier time passing through obstacles, such as gas clouds or other galaxies in the way, Narayanan said.

“We’re discovering lots of new galaxies,” he said. “Nothing like this has ever been built before.”

And the project continues to evolve, according to Narayanan. The astronomy department has received two grants to build additions to the telescope, one of which will allow it to view 16 points in the sky at once and another to build a more advanced receiver, which will help collect data about star formation, he said.

Dave Eisenstadter can be reached at deisen@gazettenet.com.