Reaching for the stars

From the Massachusetts Daily Collegian: Reaching for the stars
The University of Massachusetts astronomy department is about to go on a journey back in time, exploring galaxies over seven billion years older than the Sun.


Courtesy astro.umass.edu
The department, in cooperation with Mexico’s Instituto Nacional de Astrofisica, Optica y Electronica, is building a Large Millimeter Telescope (LMT) atop the Sierra Negra volcano located between Vera Cruz and Puebla in Mexico in an effort to explore some of the earliest formed galaxies in space.

“[It] gives us a chance to go back and use the telescope like a time machine,” said Peter Schloerb, who directed UMass’ contribution to the project.

The LMT will be able to pick up galaxies seven to eight billion years older than the sun, and should be able to study galaxies at any age in the history of the universe and maybe even the very first galaxies, he said. Data from the telescope could answer questions about origins of the solar system, he added.

Schloerb said that, at its full potential, the LMT will be the largest and most sensitive telescope of its kind in the world. It could be as large as 50 meters in diameter, which can be compared to an Olympic sized swimming pool, said Gopal Narayanan, a research associate professor of astronomy at UMass and one of the principal instrument builders in the project.

How will the LMT be able to observe such early galaxies? The secret lies in the telescope’s Redshift Search Receiver, a heterodyne receiver used to measure the spectra of objects. The main purpose of the receiver is to detect higher redshift galaxies, which are galaxies farther away in space, Narayanan said.

“We look for the earliest galaxies which are moving away from us at immense speeds,” said Narayanan, who said that once explorers know the redshift of an object, they can then determine how far away it is and therefore how old.

“Knowing this information is vital to understanding when stars and galaxies first formed in the early universe, and in understanding how the structures of galaxies and voids that we see in the present day universe were put together,” he said.

He explained that because the universe is expanding, objects farther away are moving at a higher velocity than those closer.

“When you are looking at the spectra of molecules like carbon monoxide from these distant galaxies, you can tell its frequency has changed because it is moving away at a very high velocity,” said Narayanan.

Mark Heyer, part of the science committee collecting engineering and commissioning data for the telescope, explained how measuring the shift in frequency of wavelengths can measure how fast the galaxy is receding and therefore, give way to knowledge of a galaxy’s age.

“We see galaxies moving away from us shifting to longer wavelengths,” said Heyer, who added that knowing how the universe is expanding could help determine the distance of objects.

The LMT will also allow the team to soon observe never-before-seen galaxies, Heyer said.

He explained that researchers are aware of these galaxies because certain equipment in the telescope finds information emitted from new galaxies generated by new stars.

“We know where the objects are in the sky, we know where to look but don’t know the velocity and therefore, the distance,” he said.

Narayanan said the team has just completed the commissioning stage of the process to verify the capabilities of the telescope and receiver. During this process, the astronomers observed what Narayanan described as “the first light,” which was the first time millimeter wavelength photons made their way through the telescope and all sub-systems.

“We now know its capabilities and are happy with its performance so far,” he said.

He called the endeavor one of the largest scientific projects UMass has ever taken on.

“All of it coming together, and after all these years of hard work, it is gratifying to have success and we are now filled with great hope for the future scientific potential of the Large Millimeter Telescope,” he said.

Narayanan said the LMT is located on the inactive Sierra Negra volcano at 1,500 feet. In order to function properly, the telescope must be above much of the water vapor in the atmosphere because the vapor reduces the intensity of the radiation used by the telescope, he said.

Narayanan said working at such altitude, though, is risky and physically demanding.

“Oxygen deprivation is somewhat of an issue,” he said.

A previous telescope built in the 1970s was 14 meters in diameter. Schloerb said in order to keep up with competing space exploration and telescopes, project organizers began the concept of building a larger telescope in the early 1990s.

Schloerb pointed out that the LMT at its current measurements is 32 meters in diameter, but noted that it will be close to 42 meters in diameter in approximately six months. He also said there is a 45-meter telescope in Japan and a 100-meter telescope in West Virginia.

He said the LMT upon completion will be more sensitive and accurate than even the telescope in West Virginia, even though that telescope possesses more surface area.