Thirty years ago, J. Ward Moody was pondering the existence of dwarf galaxies far, far away.
As a PhD student, Moody authored a dissertation exploring the idea that dwarf galaxies might be located in distant cosmic voids across the universe—an area of research that pushes scientists to explore the outer limits of the final frontier.
“Maybe five years ago, I revisited this whole field and brought myself up to speed on what the state of knowledge was,” Moody said. “I was astonished to learn that nobody had really pursued the problem of the dwarf galaxies even though one of the more prominent theoreticians in the United States, back in 2002, pointed this problem out.”
Dwarf galaxies are exactly what they sound like—miniature versions of galaxies. Moody is searching for them in the large and seemingly empty spaces in the universe, specifically targeting two nearby voids.
“We’re looking in the near universe for things that are just as faint as we can possibly find,” Moody said. “We knew it would be hard.”
Many scientists agree that much of the universe is composed of dark matter—matter invisible to the human eye. Because galaxies form and rotate in ways unexplainable by the laws of physics, it’s believed that obscure dark matter is influencing the composition and movement of stars.
“The understanding of dark matter really helps us put the whole picture of galaxy formation together in a much better way,” Moody said. “If there’s no dark matter, then we have all kinds of problems of understanding how galaxies can even stay together.”
Moody and his colleagues want to see if the gravity of dark matter can assemble dwarf galaxies together between larger galaxies of stars. Either finding or not finding dwarf galaxies in voids where no visible matter is present, constrains the forms that dark matter can take.
“Dwarf galaxies are so small, they are hard to find even if they are close by,” Moody said. “If you’re looking at a billion light years away, for something that small, you’ve got to have the biggest telescopes in the world.”
Scientists compete with each other to use these giant telescopes to conduct their research, convincing their peers that their work is important enough to let them use the telescope first.
Luckily, Moody’s peers recognized the significance of his research, and he spent time looking through a four-meter-wide telescope for nine days in Arizona to identify dwarf galaxy candidates based on their light emissions. From a total of nearly half a million measured objects, he has compiled a list of 2,000 possible dwarfs.
“Using the Gemini 8-meter telescope in Hawaii to more closely examine a few of the objects, we’ve proved that we are in fact finding what we said we were finding,” Moody said. “It is just that this survey also finds many non-dwarf galaxies too, and so far all confirmed objects are non-dwarfs.”
Moody and his team plan to use the Gemini telescope more extensively in the next year to
determine whether or not any are actually dwarf galaxies in these voids.
“If there are dwarf galaxies there, we’ll find them. If they’re not there, we will be able to prove to people that we should have found them,” Moody said. “It just depends on how God made his universe. Maybe there are dwarves, maybe there aren’t.”
But Moody has his own predictions about what he’ll find.
“My gut feeling is that what we’ll do is establish that they’re not there,” Moody said. “As crazy as that sounds, that would be a very, very exciting result.”
This would be exciting because it would help Moody and his colleagues find the faint limits of galaxies. It has never been determined exactly where galaxies run out, but after Moody finishes his research, we may know.
“At some point it has to stop. Or else you’d look at the nighttime sky, and it would be a blaze of light, and it’s not,” Moody said. “But we’ve never determined exactly where it is that you reach that point.”
Whatever the result, it will lead to better understanding of the unimaginable expanses of space.
“I think most theoreticians are pretty convinced that there isn’t a dwarf population, and that’s fine. If we found that they were wrong, that would be exciting. . . . Either way, it’s a step forward,” Moody said. “It’s all about trying to understand what pieces of the jigsaw puzzle we’re working with.”
More information about Moody and his research on dwarf galaxies can be found here.