In 1995 Hubble Space Telescope stared at an empty spot in the sky for 10 days in a row. The resulting image of Deep Field captured thousands of unprecedented distant galaxies. Similar observations have followed since, including the longest and deepest exposure, Hubble’s ultra-deep field. Now astronomers are looking ahead to the future and the opportunities provided by NASAthe upcoming Roman Space Telescope Nancy Grace.
The Roman Space Telescope will be able to capture an area of the sky 100 times larger than Hubble with the same exquisite sharpness. As a result, Rome’s ultra-deep field will bring together millions of galaxies, including hundreds dating back only a few hundred million years after the Big Bang. Such an observation would fuel new research in many scientific fields, from the structure and evolution of the universe to the formation of stars in space.
This distant animation begins with a view of Hubble’s ultra-deep field (outlined in blue), which is the deepest portrait of the universe ever achieved by mankind, at visible, ultraviolet and near-infrared wavelengths. The view then expanded to show a broader study of Hubble in this area of the sky (white outline), which captured about 265,000 galaxies in a large mosaic. Expanding further, we see Hubble data superimposed on a terrestrial view using data from a digital study of the sky.
An orange outline shows the field of view of NASA’s upcoming Roman Nancy Grace Space Telescope. Roman’s 18 detectors will be able to simultaneously observe a celestial space at least 100 times larger than Hubble’s ultra-deep field, with the same clear 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 ultra-deep Hubble field, which revealed countless galaxies in the universe spanning several hundred million years from Big bang. Hubble peered through a seemingly empty sky for hundreds of hours, beginning in September 2003, and astronomers discovered the galaxy’s tapestry in 2004, with more observations in the years to come.
NASA’s upcoming Roman Nancy Grace Space Telescope will be able to capture an area of the sky at least 100 times larger than Hubble with the same sharpness. Among the many observations that will be possible from this broad view of space, astronomers are considering the possibility and scientific potential of an “ultra-deep field” of the Roman space telescope. Such an observation could reveal new insights into topics ranging from star formation during the youth of the universe to the way galaxies gather in space.
The novel will enable a new science in all areas of astrophysics, from the solar system to the edge of the observable universe. Much of Roman’s observation time will be devoted to research in vast celestial areas. However, some observation time will also be available for the general astronomical community to request other projects. Rome’s ultra-deep field could be of great benefit to the scientific community, astronomers say.
“As a scientific concept, there can be exciting scientific returns in the community from Roman’s ultra-deep field observations. We would like to engage the astronomical community to think of ways in which they could take advantage of Roman’s capabilities, “said Anton Kokemoer of the Space Telescope Science Institute in Baltimore, Maryland. Koekemoer presented the Roman idea of an ultra-deep field at the 237th meeting of the American Astronomical Society, on behalf of a group of astronomers covering more than 30 institutions.
As an example, a Roman ultra-deep field can be similar to Hubble’s ultra-deep field – looking in one direction for several hundred hours to build an extremely detailed image of very faint, distant objects. And yet, while Hubble captured thousands of galaxies in this way, Roman would raise millions. As a result, it will enable new science and significantly improve our understanding of the universe.
Structure and history of the universe
Perhaps most exciting is the opportunity to study the very early universe, which corresponds to the most distant galaxies. These galaxies are also the rarest: for example, only a handful can be seen in Hubble’s ultra-deep field.
Thanks to Roman’s wide field of view and close infrared data of similar quality to Hubble’s, he could find many hundreds, if not thousands, of these youngest, most distant galaxies scattered among millions of other galaxies. This would allow astronomers to measure how they are grouped in space, as well as their age and how their stars formed.
“The novel would also provide powerful interactions with current and future ground-based and space-based telescopes, including NASA’s James Webb Space Telescope and others,” Koekemoer said.
Moving forward in space, Roman would take additional galaxies that existed about 800 million to 1 billion years after the Big Bang. At this time, galaxies are just beginning to group into groups under the influence of dark matter. While researchers have simulated this process of forming large-scale structures, a Roman ultra-deep field would provide real-world examples of testing these simulations.
Formation of stars in space time
The early universe also experienced a storm of star formation. The stars were born at speeds hundreds of times faster than what we see today. In particular, astronomers are eager to study “cosmic dawn” and “cosmic noon”, which together span between 500 million and 3 billion years after the Big Bang, when most star formations occurred, and when supermassive black holes were most active.
“Because Roman’s field of vision is so big, it will change the game. We could try not just one environment in a narrow field of vision, but instead a variety of environments caught by Roman’s wide eye. This will give us a better sense of where and when star formation took place, ”explained Sangete Malhotra of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Malhotra is a co-researcher of Roman scientific research teams working in space dawns, and has led programs that do deep spectrum with Hubble to learn about distant, young galaxies.
Astronomers are eager to measure the degree of star formation in this distant age, which can affect various factors such as the amount of heavy elements observed. The rate of star formation may depend on whether a galaxy is in a large cluster. Roman will be able to make faint spectra that will show clear “fingerprints” of these elements and give accurate distances (called redshifts) to galaxies.
“Experts from the population can ask, what are the differences between people who live in big cities compared to those in the suburbs or rural areas? Similarly, as astronomers, we can ask whether the most active star-forming galaxies live in many grouped regions or right at the ends of clusters, or live in isolation. Said Malhotra.
Big data and machine learning
One of the greatest challenges of the Roman mission will be to learn how to analyze the abundance of scientific information in the public data sets it will produce. In a sense, Roman will create new opportunities not only in terms of sky coverage, but also in data retrieval.
A Roman ultra-deep field would contain information about millions of galaxies – too many to be explored one by one. Processing the massive database will require machine learning – a form of artificial intelligence. While this is a challenge, it also offers an opportunity. “You could explore completely new questions that you couldn’t answer before,” Koekemoer said.
“The potential for discovery provided by the vast data sets of the Roman mission could lead to breakthroughs in our understanding of the universe beyond what we can currently imagine,” Koekemoer added. “This can be Roman’s enduring legacy for the scientific community: not only in the answers to the scientific questions we think we can answer, but also in the new questions we have yet to think about.”