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Team Preps to Study Dark Energy via Exploding Stars With NASA’s Roman


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Supernova Simulation
This video sparkles with synthetic supernovae from the OpenUniverse project, which simulates observations from NASA’s upcoming Nancy Grace Roman Space Telescope. More than a million exploding stars flare into visibility and then slowly fade away. The true brightness of each transient event has been magnified by a factor of 10,000 for visibility, and no background light has been added to the simulated images. The pattern of squares shows Roman’s full field of view.
Credit: NASA’s Goddard Space Flight Center and M. Troxel

The universe is ballooning outward at an ever-faster clip under the power of an unknown force dubbed dark energy. One of the major goals for NASA’s upcoming Nancy Grace Roman Space Telescope is to help astronomers gather clues to the mystery. One team is setting the stage now to help astronomers prepare for this exciting science.

“Roman will scan the cosmos a thousand times faster than NASA’s Hubble Space Telescope can while offering Hubble-like image quality,” said Rebekah Hounsell, an assistant research scientist at the University of Maryland-Baltimore county working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-principal investigator of the Supernova Cosmology Project Infrastructure Team preparing for the mission’s High-Latitude Time-Domain Survey. “We’re going to have an overwhelming amount of data, and we want to make it so scientists can use it from day one.”

Roman will repeatedly look at wide, deep regions of the sky in near-infrared light, opening up a whole new view of the universe and revealing all sorts of things going bump in the night. That includes stars being shredded as they pass too close to a black hole, intense emissions from galaxy centers, and a variety of stellar explosions called supernovae.

This data sonification transforms a vast simulation of a cosmic survey from NASA’s upcoming Nancy Grace Roman Space Telescope into a symphony of stellar explosions. Each supernova’s brightness controls its volume, while its color sets its pitch –– redder, more distant supernovae correspond to deep, low tones while bluer, nearer ones correspond to higher frequencies. The sound in stereo mirrors their locations in the sky. The result sounds like celestial wind chimes, offering a way to “listen” to cosmic fireworks.
Credit: NASA’s Goddard Space Flight Center, M. Troxel, SYSTEM Sounds (M. Russo, A. Santaguida)

Cosmic Radar Guns

Scientists estimate around half a dozen stars explode somewhere in the observable universe every minute. On average, one of them will be a special variety called type Ia that can help astronomers measure the universe.

These explosions peak at a similar intrinsic brightness, allowing scientists to find their distances simply by measuring how bright they appear.

Scientists can also study the light of these supernovae to find out how quickly they are moving away from us. By comparing how fast they’re receding at different distances, scientists will trace cosmic expansion over time.

Using dozens of type Ia supernovae, scientists discovered that the universe’s expansion is accelerating. Roman will find tens of thousands, including very distant ones, offering more clues about the nature of dark energy and how it may have changed throughout the history of the universe.

“Roman’s near-infrared view will help us peer farther because more distant light is stretched, or reddened, as it travels across expanding space,” said Benjamin Rose, an assistant professor at Baylor University in Waco, Texas, and a co-principal investigator of the infrastructure team. “And opening a bigger window, so to speak, will help us get a better understanding of these objects as a whole,” which would allow scientists to learn more about dark energy. That could include discovering new physics, or figuring out the universe’s fate.

The People’s Telescope

Members of the planning team have been part of the community process to seek input from scientists worldwide on how the survey should be designed and how the analysis pipeline should work. Gathering public input in this way is unusual for a space telescope, but it’s essential for Roman because each large, deep observation will enable a wealth of science in addition to fulfilling the survey’s main goal of probing dark energy.

Rather than requiring that many individual scientists submit proposals to reserve their own slice of space telescope time, Roman’s major surveys will be coordinated openly, and all the data will become public right away.

“Instead of a single team pursuing one science goal, everyone will be able to comb through Roman’s data for a wide variety of purposes,” Rose said. “Everyone will get to play right away.”

A light blue outline of 18 squares arranged in three rows of six that are slightly arched downward like a rainbow appears near the top left on a black background. Six more appear in a column directly beneath it, and then two more rows that are slightly taller appear to the right, and finally one more row the same length as the first one appears to the right of that. Then this whole grouping of blue squares is slightly rotated and stamped many times. The final product looks like a flower-like mandala or an intricate snowflake.
This animation shows a possible tiling pattern of part of NASA’s Nancy Grace Roman Space Telescope’s High Latitude Time-Domain Survey. The observing program, which is being designed by a community process, is expected to have two components: wide (covering 18 square degrees, a region of sky as large as about 90 full moons) and deep (covering about 5.5 square degrees, about as large as 25 full moons). This animation shows the deeper portion, which would peer back to when the universe was about 500 million years old, less than 4 percent of its current age of 13.8 billion years.
Credit: NASA’s Goddard Space Flight Center

This Is a Drill

NASA plans to announce the survey design for Roman’s three core surveys, including the High-Latitude Time-Domain Survey, this spring. Then the planning team will simulate it in its entirety.

“It’s kind of like a recipe,” Hounsell said. “You put in your observing strategy — how many days, which filters — and add in ‘spices’ like uncertainties, calibration effects, and the things we don’t know so well about the instrument or supernovae themselves that would affect our results. We can inject supernovae into the synthetic images and develop the tools we’ll need to analyze and evaluate the data.”

Scientists will continue using the synthetic data even after Roman begins observing, tweaking all aspects of the simulation and correcting unknowns to see which resulting images best match real observations. Scientists can then fine-tune our understanding of the universe’s underlying physics.

“We assume that all supernovae are the same regardless of when they occurred in the history of the universe, but that might not be the case,” Hounsell said. “We’re going to look further back in time than we’ve ever done with type Ia supernovae, and we’re not completely sure if the physics we understand now will hold up.”

There are reasons to suspect they may not. The very first stars were made almost exclusively of hydrogen and helium, compared to stars today which contain several dozen elements. Those ancient stars also lived in very different environments than stars today. Galaxies were growing and merging, and stars were forming at a furious pace before things began calming down between about 8 and 10 billion years ago.

“Roman will very dramatically add to our understanding of this cosmic era,” Rose said. “We’ll learn more about cosmic evolution and dark energy, and thanks to Roman’s large deep view, we’ll get to do much more science too with the same data. Our work will help everyone hit the ground running after Roman launches.”

For more information about the Roman Space Telescope visit www.nasa.gov/roman.

The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.

By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Media contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940

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Mar 11, 2025
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      Gretchen Imahori [National Oceanic and Atmospheric Administration’s (NOAA) National Geodetic Survey, Remote Sensing Division] presented the NOAA SatBathy (beta v2.2.3) Tool Update. During this presentation, Imahori provided an overview of the NOAA SatBathy desktop tool, example imagery, updates to the latest version, and the implementation plan for ATL24. The next session included more details about ATL24.
      Minsu Kim [United States Geological Survey (USGS), Earth Resource and Observation Center (EROS)/ Kellogg, Brown & Root (KBR)—Chief Scientist] presented the talk Satellite Derived Bathymetry (SDB) Using OLI/MSI Based-On Physics-Based Algorithm. He provided an overview of an SDB method based on atmospheric and oceanic optical properties. Kim also shared examples of imagery from the SDB product – see Figure 3.
      Figure 3. Three-dimensional renderings of the ocean south of Key West, FL created by adding SDB Digital Elevation Model (physics-based) to a Landsat Operational Land Imager (OLI) scene [top] and a Sentinel-2 Multispectral Imager (MSI) scene [bottom]. Figure credit: Minsu Kim Edward Albada [Earth Observation and Environmental Services GmbH (EOMAP)—Principal] presented the talk Satellite Lidar Bathymetry and EoappTM SLB-Online. The company EOMAP provides various services, including SDB, habitat mapping. For context, Albada provided an overview of EoappTM SDB-Online, a cloud-based software for creating SDB. (EoappTM SDB-online is one of several Eoapp apps and is based on the ICESat-2 photon data product (ATL03). Albada also provided example use cases from Eoapp – see Figure 4.
      Figure 4.A display of the Marquesas Keys (part of the Florida Keys) using satellite lidar bathymetry data from the Eoapp SLB-Online tool from EOMAP. Figure credit: Edward Albada Monica Palaseanu-Lovejoy [USGS GMEG—Research Geographer] presented on a Satellite Triangulated Sea Depth (SaTSeaD): Bathymetry Module for NASA Ames Stereo Pipeline (ASP). She provided an overview of the shallow water bathymetry SaTSeaD module, a photogrammetric method for mapping bathymetry. Palaseanu-Lovejoy presented error statistics and validation procedures. She also shared case study results from Key West, FL; Cocos Lagoon, Guam; and Cabo Rojo, Puerto Rico – see Figure 5.
      Figure 5. Photogrammetric bathymetry map of Cabo Roja, Puerto Rico displayed using the SatSeaD Satellite Triangulated Sea Depth (SaTSeaD): Bathymetry Module for NASA Ames Stereo Pipeline (ASP) module. Figure credit: Monica Palaseanu-Lovejoy Ross Smith presented a presentation on TCarta’s Trident Tools: Approachable SDB|Familiar Environment. During this presentation, Smith provided an overview of the Trident Tools Geoprocessing Toolbox deployed in Esri’s ArcPro. Smith described several use cases for the toolbox in Abu Dhabi, United Arab Emirates; Lucayan Archipelago, Bahamas; and the Red Sea.
      Michael Jasinski [GSFC—Research Hydrologist] presented on The ICESat-2 Inland Water Along Track Algorithm (ATL13). He provided an overview of the ICESat-2 data product ATL13 an inland water product that is distributed by NSIDC. Jasinski described the functionality of the ATL13 semi-empirical algorithm and proceeded to provide examples of its applications with lakes and shallow coastal waters – see Figure 6.
      Figure 6. A graphic of the network of lakes and rivers in North America that are measured by ICESat-2. Figure credit: Michael Jasinski ATL24 Data Product Update
      Christopher Parrish [Oregon State University, School of Civil and Construction Engineering—Professor] presented on ATL24: A New Global ICESat-2 Bathymetric Data Product. Parrish provided an overview of the recently released ATL24 product and described the ATL24 workflow, uncertainty analysis, and applications in shallow coastal waters. Parrish included a case study where ATL24 data were used for bathymetric mapping of Kiriwina Island, Papua New Guinea – see Figure 7.
      Figure 7. ATL24 data observed for Kiriwina Island, Papua New Guinea. Figure credit: Christopher Parrish SlideRule Demo
      J. P. Swinski [GSFC—Computer Engineer] presented SlideRule Earth: Enabling Rapid, Scalable, Open Science. Swinski explained that SlideRule Earth is a public web service that provides access to on-demand processing and visualization of ICESat-2 data. SlideRule can be used to process a subset of ICESat-2 data products, including ATL24 – see Figure 8.
      Figure 8. ATL24 data observed for Sanibel, FL as viewed on the SlideRule Earth public web client. Figure credit: SlideRule Earth SDB Accuracy
      Kim Lowell [University of New Hampshire—Data Analytics Research Scientist and Affiliate Professor] presented on SDB Accuracy Assessment and Improvement Talking Points. During this presentation, Lowell provided examples of accuracy assessments and uncertainty through the comparison of ground measurement of coastal bathymetry to those modeled from satellite data.
      Conclusion
      The ICESat-2 Satellite Bathymetry workshop fostered discussion and collaboration around the topic of SDB methods. The plenary speakers presented the state-of-the-art methods used by different sectors and organizations, including government and private entities. With the release of ATL24, ICESat-2’s new bathymetry product, it was prudent to have a conversation about new and upcoming capabilities for all methods and measurements of satellite bathymetry. Both in-person and online participants were provided with the opportunity to learn, ask questions, and discuss potential applications in their own research. The ICESat-2 applications team hopes to host more events to ensure the growth of this field to maximize the capabilities of ICESat-2 and other Earth Observing systems.
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    • By NASA
      5 Min Read 3 Black Holes Caught Eating Massive Stars in NASA Data
      A disk of hot gas swirls around a black hole in this illustration. Some of the gas came from a star that was pulled apart by the black hole, forming the long stream of hot gas on the right, feeding into the disk. Credits:
      NASA/JPL-Caltech Black holes are invisible to us unless they interact with something else. Some continuously eat gas and dust, and appear to glow brightly over time as matter falls in. But other black holes secretly lie in wait for years until a star comes close enough to snack on.
      Scientists have recently identified three supermassive black holes at the centers of distant galaxies, each of which suddenly brightened when it destroyed a star and then stayed bright for several months. A new study using space and ground-based data from NASA, ESA (European Space Agency), and other institutions presents these rare occurrences as a new category of cosmic events called “extreme nuclear transients.”
      Looking for more of these extreme nuclear transients could help unveil some of the most massive supermassive black holes in the universe that are usually quiet.
      “These events are the only way we can have a spotlight that we can shine on otherwise inactive massive black holes,” said Jason Hinkle, graduate student at the University of Hawaii and lead author of a new study in the journal Science Advances describing this phenomenon.
      The black holes in question seem to have eaten stars three to 10 times heavier than our Sun. Feasting on the stars resulted in some of the most energetic transient events ever recorded.
      This illustration shows a glowing stream of material from a star as it is being devoured by a supermassive black hole. When a star passes within a certain distance of a black hole — close enough to be gravitationally disrupted — the stellar material gets stretched and compressed as it falls into the black hole. NASA/JPL-Caltech These events as unleash enormous amount of high-energy radiation on the central regions of their host galaxies. “That has implications for the environments in which these events are occurring,” Hinkle said. “If galaxies have these events, they’re important for the galaxies themselves.”
      The stars’ destruction produces high-energy light that takes over 100 days to reach peak brightness, then more than 150 days to dim to half of its peak. The way the high-energy radiation affects the environment results in lower-energy emissions that telescopes can also detect.
      One of these star-destroying events, nicknamed “Barbie” because of its catalog identifier ZTF20abrbeie, was discovered in 2020 by the Zwicky Transient Facility at Caltech’s Palomar Observatory in California, and documented in two 2023 studies. The other two black holes were detected by ESA’s Gaia mission in 2016 and 2018 and are studied in detail in the new paper.
      NASA’s Neil Gehrels Swift Observatory was critical in confirming that these events must have been related to black holes, not stellar explosions or other phenomena.  The way that the X-ray, ultraviolet, and optical light brightened and dimmed over time was like a fingerprint matching that of a black hole ripping a star apart.
      Scientists also used data from NASA’s WISE spacecraft, which was operated from 2009 to 2011 and then was reactivated as NEOWISE and retired in 2024. Under the WISE mission the spacecraft mapped the sky at infrared wavelengths, finding many new distant objects and cosmic phenomena. In the new study, the spacecraft’s data helped researchers characterize dust in the environments of each black hole. Numerous ground-based observatories additionally contributed to this discovery, including the W. M. Keck Observatory telescopes through their NASA-funded archive and the NASA-supported Near-Earth Object surveys ATLAS, Pan-STARRS, and Catalina.
      “What I think is so exciting about this work is that we’re pushing the upper bounds of what we understand to be the most energetic environments of the universe,” said Anna Payne, a staff scientist at the Space Telescope Science Institute and study co-author, who helped look for the chemical fingerprints of these events with the University of Hawaii 2.2-meter Telescope.
      A Future Investigators in NASA Earth and Space Science and Technology (FINESST) grant from the agency helped enable Hinkle to search for these black hole events. “The FINESST grant gave Jason the freedom to track down and figure out what these events actually were,” said Ben Shappee, associate professor at the Institute for Astronomy at the University of Hawaii, a study coauthor and advisor to Hinkle.
      Hinkle is set to follow up on these results as a postdoctoral fellow at the University of Illinois Urbana-Champaign through the NASA Hubble Fellowship Program. “One of the biggest questions in astronomy is how black holes grow throughout the universe,” Hinkle said.
      The results complement recent observations from NASA’s James Webb Space Telescope showing how supermassive black holes feed and grow in the early universe. But since only 10% of early black holes are actively eating gas and dust, extreme nuclear transients — that is, catching a supermassive black hole in the act of eating a massive star — are a different way to find black holes in the early universe.
      Events like these are so bright that they may be visible even in the distant, early universe. Swift showed that extreme nuclear transients emit most of their light in the ultraviolet. But as the universe expands, that light is stretched to longer wavelengths and shifts into the infrared — exactly the kind of light NASA’s upcoming Nancy Grace Roman Space Telescope was designed to detect.
      With its powerful infrared sensitivity and wide field of view, Roman will be able to spot these rare explosions from more than 12 billion years ago, when the universe was just a tenth of its current age. Scheduled to launch by 2027, and potentially as early as fall 2026, Roman could uncover many more of these dramatic events and offer a new way to explore how stars, galaxies, and black holes formed and evolved over time.
      “We can take these three objects as a blueprint to know what to look for in the future,” Payne said.
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