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The cosmos is an ever-evolving expanse where galaxies are constantly on the move, merging and altering their forms. However, due to the immense timescales involved—millions to billions of years—telescopes provide us only fleeting glimpses of these celestial transformations within our human lifespan.
Nevertheless, galaxies preserve remnants of their histories, offering vital insights into their formation. The forthcoming Nancy Grace Roman Space Telescope is set to enhance our understanding by capturing high-resolution images of galaxies in close proximity to Earth, effectively searching for these fossils of cosmic evolution.
Astronomers, backed by a NASA grant, are developing a survey known as RINGS (the Roman Infrared Nearby Galaxies Survey) aimed at gathering these exquisite images. The team is also creating tools for public access that will aid the broader astronomical community once Roman begins its data collection. It is important to note that RINGS remains a preliminary proposal and its final implementation will depend on various factors during Roman’s operational phase.
Distinctively equipped for the RINGS initiative, Roman boasts a spatial resolution comparable to that of the famed Hubble Space Telescope, but with a remarkable wide field of view—200 times that of Hubble’s infrared scope. This unique combination allows it to survey the skies in a manner that complements Hubble’s focus on narrower fields.
Uncovering the Past: Cosmic Archaeology
Astronomers are restricted to observing only short intervals in the evolution of galaxies, making it challenging to trace their developmental paths. Fortunately, galaxies hold clues within their stellar compositions, reminiscent of how earthly fossils reveal evolutionary histories.
These stellar remnants, often referred to as “galactic fossils,” comprise ancient star clusters that encompass the timeline of a galaxy’s formation and development, including insights into the galaxy’s initial chemical makeup at the time the stars emerged. Robyn Sanderson, the deputy principal investigator for RINGS at the University of Pennsylvania, compares studying these stellar structures to archaeological excavation, where one must carefully sort through remnants to delineate connections between them.
With Roman’s exceptional resolution, scientists will be well-equipped to identify these galactic fossils, ranging from extensive tidal tails encircling a galaxy to intricate stellar streams within. Such large-scale structures, uniquely resolvable by Roman, can reveal significant clues about a galaxy’s merger history. Sanderson articulates the ambition behind this research: “To reassemble these fossils in order to look back in time and understand how these galaxies came to be.”
Exploring the Enigmatic Dark Matter
RINGS also holds the potential to deepen our understanding of dark matter, the elusive substance constituting the majority of a galaxy’s mass. Ultra-faint dwarf galaxies, which are predominantly made up of dark matter with minimal normal matter, serve as particularly valuable subjects for testing dark matter theories. Raja GuhaThakurta from the University of California, Santa Cruz, points out that these ultra-faint galaxies can essentially be viewed as pure dark matter concentrations, offering an ideal environment for study.
With its expansive field of view and superior resolution, Roman will scrutinize these ultra-faint galaxies, aiding in the assessment of various dark matter theories. This investigation is crucial, as dark matter comprises an astounding 80% of the universe’s total matter, leaving ordinary matter—making up the remaining 20%—in the shadows of cosmic understanding.
Investigation into dark matter extends beyond ultra-faint galaxies; the star structures surrounding an average-sized galaxy also hold significant information. The halos of these galaxies can provide essential hints towards estimating the amount of dark matter they harbor. However, the colossal size of these halos—often 15 to 20 times larger than the galaxies themselves—poses challenges for current observation techniques.
At present, astronomers have reliable measurements only for our Milky Way and its neighboring Andromeda galaxy. Ben Williams, the principal investigator for RINGS at the University of Washington, explains how Roman’s capabilities could revolutionize this field: “We only have reliable measurements of the Milky Way and Andromeda, because those are close enough that we can get measurements of a large number of stars distributed across their stellar halos. So, with Roman, all of a sudden we’ll have 100 or more of these fully resolved galaxies.”
Anticipated to launch by May 2027, the Roman Space Telescope is expected to transform our comprehension of galaxies significantly. By focusing on nearby galaxies similar in size and age to the Milky Way, RINGS could provide invaluable insights into the formation and evolution of our cosmic neighborhood.
The Nancy Grace Roman Space Telescope is under the direction of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with contributions from NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a diverse team of scientists from various research institutions. Key industrial partners include BAE Systems, Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
Source
www.nasa.gov