From The NASA Goddard Space Flight Center: “NASA Missions Probe Game-Changing Cosmic Explosion” 

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From The NASA Goddard Space Flight Center

By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md

Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md

Gamma-ray burst 211211A, the location of which is circled in red, erupted on the outskirts of a spiral galaxy around 1 billion light-years away in the constellation Boötes. The NASA/ESA Hubble Space Telescope captured the image with its Wide Field Camera 3 and Advanced Camera for Surveys. Credit: NASA, ESA, Rastinejad et al. (2022), and Gladys Kober (Catholic Univ. of America)

On Dec. 11, 2021, NASA’s Neil Gehrels Swift Observatory and Fermi Gamma-ray Space Telescope detected a blast of high-energy light from the outskirts of a galaxy around 1 billion light-years away. The event has rattled scientists’ understanding of gamma-ray bursts (GRBs), the most powerful events in the universe.

For the last few decades, astronomers have generally divided GRBs into two categories. Long bursts emit gamma rays for two seconds or more and originate from the formation of dense objects like black holes in the centers of massive collapsing stars. Short bursts emit gamma rays for less than two seconds and are caused by mergers of dense objects like neutron stars. Scientists sometimes observe short bursts with a following flare of visible and infrared light called a kilonova.

“This burst, named GRB 211211A, was paradigm-shifting as it is the first long-duration gamma-ray burst traced to a neutron star merger origin,” said Jillian Rastinejad, a graduate student at Northwestern University in Evanston, Illinois, who led one team that studied the burst.

“The high-energy burst lasted about a minute, and our follow-up observations led to the identification of a kilonova. This discovery has deep implications for how the universe’s heavy elements came to be.”

NASA’s Fermi, Swift Capture Revolutionary Gamma-Ray Burst.
Watch to learn how an event called GRB 211211A rocked scientists’s understanding of gamma-ray bursts – the most powerful explosions in the cosmos. Credit: NASA’s Goddard Space Flight Center.

A classic short gamma-ray burst begins with two orbiting neutron stars, the crushed remnants of massive stars that exploded as supernovae. As the stars circle ever closer, they strip neutron-rich material from each other. They also generate gravitational waves, or ripples in space-time – although none were detected from this event.

Eventually the neutron stars collide and merge, creating a cloud of hot debris emitting light across multiple wavelengths. Scientists hypothesize that jets of high-speed particles, launched by the merger, produce the initial gamma-ray flare before they collide with the wreckage. Heat generated by the radioactive decay of elements in the neutron-rich debris likely creates the kilonova’s visible and infrared light. This decay results in the production of heavy elements like gold and platinum.

“Many years ago, Neil Gehrels, an astrophysicist and Swift’s namesake, suggested that neutron star mergers could produce some long bursts,” said Eleonora Troja, an astrophysicist at the University of Rome who led another team that studied the burst. “The kilonova we observed is the proof that connects mergers to these long-duration events, forcing us to rethink how black holes are formed.”

Fermi and Swift detected the burst simultaneously, and Swift was able to rapidly identify its location in the constellation Boötes, enabling other facilities to quickly respond with follow-up observations. Their observations have provided the earliest look yet at the first stages of a kilonova.

Many research groups have delved into the observations collected by Swift, Fermi, the Hubble Space Telescope, and others.

Some have suggested the burst’s oddities could be explained by the merger of a neutron star with another massive object, like a black hole. The event was also relatively nearby, by gamma-ray burst standards, which may have allowed telescopes to catch the kilonova’s fainter light. Perhaps some distant long bursts could also produce kilonovae, but we haven’t been able to see them.

Two neutron stars begin to merge in this illustration, blasting a jet of high-speed particles and producing a cloud of debris. Scientists think these kinds of events are factories for a significant portion of the universe’s heavy elements, including gold. Credits: A. Simonnet (Sonoma State Univ.) and NASA’s Goddard Space Flight Center.

The light following the burst, called the afterglow emission, also exhibited unusual features. Fermi detected high-energy gamma rays starting 1.5 hours post-burst and lasting more than 2 hours. These gamma rays reached energies of up to 1 billion electron volts. (Visible light’s energy measures between about 2 and 3 electron volts, for comparison.)

“This is the first time we’ve seen such an excess of high-energy gamma rays in the afterglow of a merger event. Normally that emission decreases over time,” said Alessio Mei, a doctoral candidate at the Gran Sasso Science Institute in L’Aquila, Italy, who led a group that studied the data. “It’s possible these high-energy gamma rays come from collisions between visible light from the kilonova and electrons in particle jets. The jets could be weakening ones from the original explosion or new ones powered by the resulting black hole or magnetar.”

Scientists think neutron star mergers are a major source of the universe’s heavy elements. They based their estimates on the rate of short bursts thought to occur across the cosmos. Now they’ll need to factor long bursts into their calculations as well.

A team led by Benjamin Gompertz, an astrophysicist at the University of Birmingham in the United Kingdom, looked at the entire high-energy light curve, or the evolution of the event’s brightness over time. The scientists noted features that might provide a key for identifying similar incidents – long bursts from mergers – in the future, even ones that are dimmer or more distant. The more astronomers can find, the more they can refine their understanding of this new class of phenomena.

On Dec. 7, 2022, papers led by Rastinejad, Troja, and Mei were published in the scientific journal Nature [below], and a paper led by Gompertz was published in Nature Astronomy [below].

“This result underscores the importance of our missions working together and with others to provide multiwavelength follow up of these kinds of phenomenon,” said Regina Caputo, Swift project scientist, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Similar coordinated efforts have hinted that some supernovae might produce short bursts, but this event is the final nail in the coffin for the simple dichotomy we’ve used for years. You never know when you might find something surprising.”

NASA’s Goddard Space Flight Center manages the Swift and Fermi missions.

Swift is a collaboration with The Pennsylvania State University, the DOE’s Los Alamos National Laboratory in New Mexico, and Northrop Grumman Space Systems in Dulles, Virginia, with important contributions from partners in the United Kingdom and Italy.

Fermi is a collaboration with the U.S. Department of Energy, with important contributions from partners in France, Germany, Italy, Japan, Sweden, and the United States.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). Goddard manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Science papers:
Nature Astronomy

See the full article here.

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NASA/Goddard Campus

NASA’s Goddard Space Flight Center, Greenbelt, MD is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

GSFC also operates two spaceflight tracking and data acquisition networks (the NASA Deep Space Network and the Near Earth Network); develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration.

GSFC manages operations for many NASA and international missions including the NASA/ESA Hubble Space Telescope; the Explorers Program; the Discovery Program; the Earth Observing System; INTEGRAL; MAVEN; OSIRIS-REx; the Solar and Heliospheric Observatory ; the Solar Dynamics Observatory; Tracking and Data Relay Satellite System ; Fermi; and Swift. Past missions managed by GSFC include the Rossi X-ray Timing Explorer (RXTE), Compton Gamma Ray Observatory, SMM, COBE, IUE, and ROSAT. Typically, unmanned Earth observation missions and observatories in Earth orbit are managed by GSFC, while unmanned planetary missions are managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California.

Goddard is one of four centers built by NASA since its founding on July 29, 1958. It is NASA’s first, and oldest, space center. Its original charter was to perform five major functions on behalf of NASA: technology development and fabrication; planning; scientific research; technical operations; and project management. The center is organized into several directorates, each charged with one of these key functions.

Until May 1, 1959, NASA’s presence in Greenbelt, MD was known as the Beltsville Space Center. It was then renamed the Goddard Space Flight Center (GSFC), after Robert H. Goddard. Its first 157 employees transferred from the United States Navy’s Project Vanguard missile program, but continued their work at the Naval Research Laboratory in Washington, D.C., while the center was under construction.

Goddard Space Flight Center contributed to Project Mercury, America’s first manned space flight program. The Center assumed a lead role for the project in its early days and managed the first 250 employees involved in the effort, who were stationed at Langley Research Center in Hampton, Virginia. However, the size and scope of Project Mercury soon prompted NASA to build a new Manned Spacecraft Center, now the Johnson Space Center, in Houston, Texas. Project Mercury’s personnel and activities were transferred there in 1961.

The Goddard network tracked many early manned and unmanned spacecraft.

Goddard Space Flight Center remained involved in the manned space flight program, providing computer support and radar tracking of flights through a worldwide network of ground stations called the Spacecraft Tracking and Data Acquisition Network (STDN). However, the Center focused primarily on designing unmanned satellites and spacecraft for scientific research missions. Goddard pioneered several fields of spacecraft development, including modular spacecraft design, which reduced costs and made it possible to repair satellites in orbit. Goddard’s Solar Max satellite, launched in 1980, was repaired by astronauts on the Space Shuttle Challenger in 1984. The Hubble Space Telescope, launched in 1990, remains in service and continues to grow in capability thanks to its modular design and multiple servicing missions by the Space Shuttle.

Today, the center remains involved in each of NASA’s key programs. Goddard has developed more instruments for planetary exploration than any other organization, among them scientific instruments sent to every planet in the Solar System. The center’s contribution to the Earth Science Enterprise includes several spacecraft in the Earth Observing System fleet as well as EOSDIS, a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during extra-vehicular activity, and operates the Lunar Reconnaissance Orbiter, a spacecraft designed to study the Moon in preparation for future manned exploration.

The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs.] NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.