In 1995, it became Hubble Space Telescope stared at an empty patch of sky for 10 days in a row. The resulting Deep Field image captured thousands of previously unseen, distant galaxies. Similar observations have followed since then, including the longest and deepest exposure, the Hubble Ultra Deep Field. Now astronomers are looking ahead and the possibilities of the future NASA‘s upcoming Nancy Grace Roman Space Telescope.
The Roman space telescope is capable of photographing an area of the sky 100 times larger than Hubble with the same exquisite sharpness. As a result, a Roman ultra-deep field would gather millions of galaxies, including hundreds dating back to just a few hundred million years after the big bang. Such an observation would yield new studies of several scientific fields, ranging from the structure and evolution of the universe to star formation over cosmic time.
This zoom-out animation begins with a display of the Hubble Ultra Deep Field (outlined in blue), representing the deepest portrait of the universe that man has ever achieved at visible, ultraviolet, and near-infrared wavelengths. The view is then expanded to show a broader Hubble overview of the area of the sky (white outline) that captured about 265,000 galaxies in a large mosaic. Extended further, we see Hubble data superimposed on a terrestrial view using data from Digitized Sky Surveys.
An orange sketch shows the field of view of NASA’s upcoming Roman telescope Nancy Grace. Rome’s 18 detectors will be able to observe a sky area at least 100 times larger than the Hubble Ultra Deep Field at one time, with the same sharp sharpness as Hubble.
Credit: NASA, ESA, A. Koekemoer (STScI) and A. Pagan (STScI)
One of the most iconic images of the Hubble Space Telescope is the Hubble Ultra Deep Field, which revealed countless galaxies across the universe and stretched back within a few hundred million years. Big bang. Hubble looked at a single piece of seemingly empty sky for hundreds of hours beginning in September 2003, and astronomers unveiled the galaxy blanket in 2004 with several observations in subsequent years.
NASA’s upcoming Roman telescope Nancy Grace will be able to photograph an area of the sky at least 100 times larger than Hubble with the same sharp sharpness. Among the many observations that will be made possible by this broad view of the cosmos, astronomers are considering the possibility and scientific potential of a “ultra-deep field” Roman space telescope. Such an observation could reveal new insights into motifs ranging from star formation during the youth of the universe to the way galaxies gather in space.
The novel will enable new science in all areas of astrophysics, from the solar system to the edge of the observable universe. Much of Rome’s observation time will be spent studying broad swaths of the sky. However, some observation time will also be available for the general astronomical community to request other projects. A Roman ultra-deep field could greatly benefit the scientific community, astronomers say.
“As a social science concept, there could be exciting scientific returns from ultra-deep field observations by Roman. We want to engage the astronomical community to think of ways in which they can harness the capabilities of the Romans, ”said Anton Koekemoer of the Space Telescope Science Institute in Baltimore, Maryland. Koekemoer presented the Roman ultra-deep field time at the 237th meeting of the American Astronomical Society on behalf of a group of astronomers spanning more than 30 institutions.
As an example, a Roman ultra-deep field could resemble Hubble Ultra Deep Field – look in a single direction for a few hundred hours to build an extremely detailed image of very faint, distant objects. But while Hubble captured thousands of galaxies in this way, Roman would collect millions. As a result, it would enable new science and greatly improve our understanding of the universe.
The structure and history of the universe
Perhaps most intriguing is the opportunity to study the very early universe corresponding to the most distant galaxies. These galaxies are also the rarest: for example, only a handful are seen in the Hubble Ultra Deep Field.
Thanks to Roman’s wide field of view and near-infrared data of the same quality as Hubbles, it could detect hundreds or possibly thousands of these youngest, most distant galaxies, scattered among the millions of other galaxies. It would let astronomers measure how they group themselves in space as well as their age and how their stars are formed.
“The novel would also provide powerful synergies with current and future telescopes on Earth and in space, including NASA’s James Webb Space Telescope and others,” Koekemoer said.
Going forward in cosmic time, Roman would capture additional galaxies that existed about 800 million to 1 billion years after the big bang. At that time, galaxies were just beginning to gather in clusters under the influence of dark matter. While scientists have simulated this process to form large structures, a Roman ultra-deep field would provide real-world examples to test these simulations.
Star formation over cosmic time
The early universe also experienced a firestorm of star formation. Stars were born at speeds hundreds of times faster than what we see today. Astronomers in particular are eager to study “cosmic dawn” and “cosmic dinner”, which together cover a time 500 million to 3 billion years after the big bang, when most star formation took place, as well as when supermassive black holes were most active.
“Because Roman’s field of vision is so large, it will change games. We would be able to try not only an environment in a narrow field of vision, but instead a variety of environments captured by the eyes of Roman witnesses. This will give us a better sense of where and when star formation took place, ”explained Sangeeta Malhotra of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Malhotra is a co-researcher in the Roman science research teams working on the cosmic dawn and has led deep spectroscopy programs with Hubble to learn about distant, young galaxies.
Astronomers are eager to measure star formation rates in this distant epoch, which can affect a number of factors such as the amount of heavy elements observed. Star formation rates may depend on whether a galaxy is in a large cluster. The novel will be able to take faint spectra, showing different “fingerprints” of these elements and giving exact distances (called redshifts) of galaxies.
“Population experts may ask, what are the differences between people living in big cities, versus those in suburbs or rural areas? Likewise, as astronomers we may ask, do the most active star-forming galaxies live in highly clustered areas or right at the edges of clusters, or do they live in isolation? Said Malhotra.
Big Data and Machine Learning
One of the greatest challenges of the Roman mission will be to learn to analyze the abundance of scientific information in the public datasets that it will produce. In a way, Roman will create new opportunities not only in terms of sky coverage, but also in the field of data mining.
A Roman ultra-deep field would contain information on millions of galaxies – far too many to be studied by scientists at a time. Machine learning – a form of artificial intelligence – is needed to process the massive database. While this is a challenge, it also provides an opportunity. “You could explore completely new issues that you had not addressed before,” Koekemoer said.
“The potential for discovery made possible by the vast datasets of the Roman mission could lead to breakthroughs in our understanding of the universe beyond what we currently imagine,” Koekemoer added. “It could be Rome’s lasting legacy for the scientific community: not only in answering the scientific questions we think we can address, but also new questions that we have not yet thought about.”