Texas A&M astronomer Darren DePoy served as the project scientist for the Dark Energy Camera, one of the most powerful survey instruments of its kind that is able to see light from more than 100,000 galaxies up to 8 billion light years away in each snapshot. (Reidar Hahn/Fermilab.)
For his part, Ferguson describes stellar streams as objects such as globular clusters or dwarf galaxies that have been ripped apart by the Milky Way and smeared across the sky. They can offer important information about the Milky Way’s formation history, sometimes coined as Galactic archaeology. However, because they are composed of relatively few stars spread out over a large area of sky, these stellar streams are extremely difficult to find, even for an instrument as powerful as DECam.
“They contain information about the current state of the Milky Way and can be used to characterize its gravitational field and estimate its mass,” Ferguson said. “Additionally, small disturbances in streams can be used to explore Milky Way substructure, which includes constraining different dark matter models.”
Beyond helping with analysis of the locations and orientations of the streams, Ferguson used orbit models to look for any previously known streams that could be associated with the newly discovered DES streams. He also searched for any nearby globular clusters or dwarf galaxies that could have acted as progenitors for the streams.
“I think this paper contains some really exciting results and opens the door for a lot more work on this topic, helping us to understand our place in the Milky Way Galaxy and how it evolved to the state we see it in today,” Ferguson added.
An international collaboration
Prior to the new discoveries by DES, only about two dozen stellar streams had been discovered. Many of them were found by the Sloan Digital Sky Survey, a precursor to the Dark Energy Survey. Since there is no universally accepted naming convention for stellar streams, the Dark Energy Survey has reached out to schools in Chile and Australia, where students and their teachers have worked together to name the streams after aquatic words in native languages from northern Chile and aboriginal Australia. Read more about the names in this story from Symmetry magazine.
Pace says he got involved in DES data-vetting as a representative of the Milky Way (MW) working group, in which he works with Marshall and Texas A&M astronomer Louis Strigari to discover and follow up on new MW satellites. He admits that makes him a little biased toward MW science when it comes to identifying DES high points thus far. Beyond the field-of-streams paper involving Ferguson, Pace says his top three in no particular order consist of the first year of cosmology results (“the science here is the primary mission of the DES and came out better than expected and will only get better with more data”), the discovery of the optical counterpart to the neutron star merger (“first discovered via gravitational waves”) and the search for MW satellites papers (“so far, there have been around 23 objects found within the survey, which is higher than I expected.”)
Texas A&M Astronomer Jennifer Marshall Witnesses Cosmic History In Chile
Papers drawn from the first years of DES data can be found online, along with an animation of several of the newly discovered streams.
DES plans one more major public data release after the completion of the survey’s five-year mission, which runs through 2018. This future release will include nearly twice as many exposures as featured in the current release.
In addition to DePoy, Marshall and Strigari, fellow Texas A&M astronomers and Mitchell Institute members Lucas Macri, Casey Papovich and Nicholas Suntzeff are full members of the 400-plus-member international DES collaboration that spans 26 institutions and seven countries as well as the gamut of science and engineering in the search for answers regarding the universe’s accelerated expansion. Texas A&M statistician James Long and Mitchell Institute Postdoctoral Fellow Peter Brown also are external collaborators.
Read more on the announcement – including quotes from affiliated scientists, administrators and funding entities – via the official Fermilab press release.
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Media contact: Shana K. Hutchins, (979) 862-1237 or email@example.com, Andrew Pace, (979) 845-7778 or firstname.lastname@example.org or Peter Ferguson, (979) 845-7778 or email@example.com