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Written
by: Anavi Uppal
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Oct. 15, 2024
Burst Chasers
小优视频ampa astronomer鈥檚 research engages students and a global community of amateur scientists in search of answers to questions of the universe
A gamma-ray burst. Photo courtesy of NASA鈥檚 Goddard Space Flight Center
Billions of light years away, a jet of high-energy radiation explodes from a newborn black hole or neutron star, aiming directly for Earth. This is a gamma-ray burst (GRB), and for a brief moment, it is the brightest source of light in the universe, putting out more energy in seconds than our sun will emit in its lifetime.
Within 15 minutes of its light reaching Earth, researchers around the globe have been alerted to point their telescopes at the afterglow of the GRB. One of those scientists is Amy Lien, an assistant professor of physics and astronomy at 小优视频ampa. Lien is spearheading a project that engages NASA volunteers to help figure out just what causes GRBs.
MYSTERIOUS ORIGINS
GRBs were discovered by accident during the Cold War. After the U.S. and Soviet Union agreed to ban the use of nuclear weapons in space, the U.S. suspected that the Soviets might try to circumvent the treaty and launched spy satellites to detect gamma rays from possible nuclear tests in space. The satellites did detect gamma rays, but they weren鈥檛 man-made.
鈥淔ortunately, they checked their data, so they realized it was not from nuclear bombs,鈥 Lien said.
Researchers currently know about two processes that can trigger a GRB. The longest bursts, lasting anywhere from several seconds to hours, are emitted by massive stars dying violent deaths. Their outer layers explode into a bright supernova, while their inner layers collapse to form a dense neutron star or black hole. Other GRBs last less than two seconds and are caused by the merger of either two neutron stars or one neutron star and one black hole, resulting in the creation of a brand-new black hole.
But researchers also have seen some GRBs that don鈥檛 match these descriptions. These GRBs last longer than two seconds, but their pulse shapes 鈥 recorded by telescopes and represented visually as peaks and drops over time on a line graph 鈥 seem to indicate that they were caused by the merger of two neutron stars, not a supernova.
鈥淚t鈥檚 just not consistent with our current picture of. how the pulses should look for these sources. Maybe we were completely wrong, and we have to revise some of the theoretical models,鈥 Lien said.
Scientists like Lien want to figure out what causes these unusual bursts. Since GRBs are so bright, telescopes can detect them even from billions of light years away. Signals from that far away take billions of years to reach us, which means that distant GRBs provide a rare way for scientists to study the history of the early universe.
OPENING SCIENCE TO THE PUBLIC
Lien began studying GRBs when she worked at NASA鈥檚 Goddard Space Flight Center from 2011 to 2021 as a mission support specialist for the Neil Gehrels Swift Observatory. Swift was launched into space in 2004 to study GRBs in wavelengths across the electromagnetic spectrum, from radio to gamma ray. The observatory watches one-sixth of the sky at a time in an attempt to catch new GRBs. Even after the initial gamma-ray signal of a GRB disappears, Swift can see its afterglow in less energetic wavelengths.
鈥淲e don鈥檛 know when or where it鈥檚 going to happen,鈥 Lien said. 鈥淵ou have to react immediately.鈥 Swift catches multiple GRBs per week, and it has seen over 1,600 GRBs in its 20 years.
While at Goddard, Lien began getting requests from researchers asking if she鈥檇 seen GRBs with certain unusual pulse shapes. Though a few NASA interns had worked on classifying bursts over the summers, there had been no largescale effort to classify them. 鈥淪o that鈥檚 why we thought about having a citizen-science project to engage the public and help us do this,鈥 Lien said.
Lien developed a project called Burst Chaser for the popular citizen-science website Zooniverse. The project was launched to the public in January and calls on volunteers of any experience level to identify GRBs in Swift data and classify their shapes. 小优视频ampa students Katherine Kurilov 鈥25, Carter Murawski 鈥25 and Sebastian Reisch 鈥24 helped Lien develop the project. Murawski, a physics major minoring in math and computer science, converted the Swift data into a user-friendly interface for Zooniverse. 鈥淗e鈥檚 really our main programmer 鈥 this project wouldn鈥檛 exist without him,鈥 Lien said.
Burst Chaser volunteers are shown graphs of gamma-ray counts versus time for each GRB and are given a brief tutorial on how to interpret them. There are two separate workflows in the project: One asks volunteers to decide if a graph shows a real GRB or just background noise, and the other asks them to draw boxes around individual peaks in a burst pulse. The different peaks are caused by shocks within a GRB鈥檚 jet, and studying them can provide scientists with important information about how the jet was created by the black hole or neutron star.听
Carter Murawski 鈥25 is the project鈥檚 main programmer. Photo by Bob Thompson
LOOKING AT GRBS WITH FRESH EYES
But why not use artificial intelligence to classify bursts instead of using volunteers? It turns out that AI doesn鈥檛 produce accurate classification results when compared to scientists, but the citizen scientists on Zooniverse do it quite well, even though most of them don鈥檛 have any formal training in astronomy.
鈥淢aybe somebody just likes astrophysics, and they have no experience at it. Maybe somebody just goes on the website for fun. Maybe it鈥檚 a kid. It鈥檚 cool to see that you can get accurate results from stuff like that,鈥 Murawski said.
Sometimes, NASA volunteers pick up on patterns that Lien didn鈥檛 notice. Lien鈥檚 personal interest is finding bursts that start with a peak and taper off into a low tail, since those are the ones that don鈥檛 match scientists鈥 current theoretical explanations. She asked a group of volunteers to search for that shape in Swift data. When she looked at their classifications, she noticed that some of the bursts had shorter tails than she expected, and she wouldn鈥檛 have selected them herself.
鈥淭hose will be interesting ones 鈥 we should probably take a closer look at them to see whether they also have mysterious physical origins,鈥 Lien said.
After the Burst Chaser project concludes, the classifications from the volunteers could be used as training data to teach AI to accurately classify GRB pulses. But working with citizen scientists is about more than just results. It鈥檚 about engaging the community.
鈥淲hat I learned is that there鈥檚 a lot of people genuinely super interested in astronomy, and they just want to learn more and actually help,鈥 Lien said. 鈥淭his is not their job; they鈥檙e not being paid. They participate just because they鈥檙e interested.鈥
Burst Chasers, from left: Sebastian Reisch 鈥24, Assistant Professor Amy Lien and Carter Murawski 鈥25. Photo by Bob Thompson
A COMMUNITY OF BURST CHASERS
Danny Roylance is a citizen scientist and U.S. Army veteran from Salt Lake City. For him, working on Burst Chaser is a way to reignite his childhood passion for astronomy while doing real NASA science. Roylance has been working on citizen science astronomy projects for about five years and has become such a prolific contributor that he was selected by NASA to help Lien develop the Burst Chaser project. Roylance was part of the first core group of NASA volunteers who tested the workflows and gave feedback to Lien.
鈥淎my Lien is probably the neatest citizen-science principal investigator that I鈥檝e had the pleasure of working with,鈥 he said. 鈥淪he鈥檚 got a busy schedule, but you can ask a question that can be extremely advanced or it can be really basic, and she will explain it.鈥 Lien invites top-contributing volunteers like him to weekly research meetings, so Roylance has been on calls with NASA volunteers from all around the globe. He sees this diversity as a huge benefit to the science.
鈥淲ith all kinds of different religions, races, and all that kind of stuff, you鈥檙e gonna get a lot of viewpoints over the subject,鈥 Roylance said.
The dedication of some of the volunteers has completely surprised Lien. 鈥淭here are two people from India, and our meeting obviously is not at a convenient time for them 鈥 it鈥檚 like 2 or 3 a.m., but they still call in every two weeks,鈥 she said. 鈥淚 was like, 鈥橶ait a second, you don鈥檛 need to sleep?鈥欌
Her students also have been dedicated to the project. Murawski says he has enjoyed working with Lien. 鈥淪he gives out tasks that she would have to do herself, so it鈥檚 like a collaboration with her rather than feeling like I鈥檓 just doing the grunt work,鈥 he said. 鈥淲e鈥檙e all working together to accomplish everything.鈥 He hopes to do software engineering or data science work after he graduates, and programming for Burst Chaser has given him valuable experience in that area.
Last summer, Lien created a catalog of the completed classifications for astronomers to use, and Murawski is working to make this information publicly available on a web page. The catalog shows each burst shape and lists every GRB that matches that profile. Lien hopes to work with gamma-ray theorists to connect each burst shape in the catalog to a model of what the GRB鈥檚 source looked like.
A F小优视频URE OF SOLVING MYSTERIES
A citizen-science project isn鈥檛 like a typical science project with a clear start and end. 鈥淚 feel like it鈥檚 more organic, which means it grows, and the direction shifts by itself 鈥 because it鈥檚 all human, right?鈥 Lien said. Once all the GRBs in Burst Chaser are classified, the current Zooniverse project will be retired. However, Lien hopes to do a Burst Chaser 2.0 with spectra of GRBs.
Spectra are images that show the intensity of light at different wavelengths. Each element on the periodic table has a unique fingerprint that shows up as dark and bright regions in a spectrum. When astronomers see these regions in a GRB鈥檚 spectrum, they can use them to figure out the chemical makeup of the material that the GRB鈥檚 jet is plowing through. The location of these fingerprints also reveals how far away a GRB鈥檚 source is.
Lien admitted that she sometimes gets caught up with problem-solving and forgets how exciting the research is, but seeing the enthusiasm of her students and volunteer scientists reminds her.
鈥淚 got the gift of working in high energy astrophysics, which is what I wanted all along,鈥 Roylance said. 鈥淚t鈥檚 like we鈥檙e Arctic explorers looking for that big mystery.鈥
鈥淚 enjoy that pure curiosity,鈥 Lien said.
Gamma-Ray Grant Will Expand Work
In August, Assistant Professor of Physics and Astronomy Amy Lien was awarded a two-year, $233,768 grant from the National Science Foundation to continue and expand her work. Along with fellow faculty members Denija Crnojevic, assistant professor of physics and astronomy, and Simon Schuler, associate professor of physics and astronomy, Lien will collaborate with scientists at NASA鈥檚 Goddard Space Flight Center on studying gamma-ray bursts with machine learning, space telescopes and citizen science. The grant also will allow two students to visit Goddard and perform research there for 10 weeks.
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鈥淭he goal of this grant is to enable collaboration between primarily undergraduate institutions and NASA,鈥 said Lien. 鈥(It) provides a unique opportunity for students and faculty to work with Goddard scientists and explore the mysterious origins of gamma-ray bursts.鈥
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TITLE
Billions of light years away, a jet of high-energy radiation explodes from a newborn black hole or neutron star, aiming directly for Earth. This is a gamma-ray burst (GRB), and for a brief moment, it is the brightest source of light in the universe, putting out more energy in seconds than our sun will emit in its lifetime.
Within 15 minutes of its light reaching Earth, researchers around the globe have been alerted to point their telescopes at the afterglow of the GRB. One of those scientists is Amy Lien, an assistant professor of physics and astronomy at 小优视频ampa. Lien is spearheading a project that engages NASA volunteers to help figure out just what causes GRBs.
MYSTERIOUS ORIGINS
GRBs were discovered by accident during the Cold War. After the U.S. and Soviet Union agreed to ban the use of nuclear weapons in space, the U.S. suspected that the Soviets might try to circumvent the treaty and launched spy satellites to detect gamma rays from possible nuclear tests in space. The satellites did detect gamma rays, but they weren鈥檛 man-made.
鈥淔ortunately, they checked their data, so they realized it was not from nuclear bombs,鈥 Lien said.
Researchers currently know about two processes that can trigger a GRB. The longest bursts, lasting anywhere from several seconds to hours, are emitted by massive stars dying violent deaths. Their outer layers explode into a bright supernova, while their inner layers collapse to form a dense neutron star or black hole. Other GRBs last less than two seconds and are caused by the merger of either two neutron stars or one neutron star and one black hole, resulting in the creation of a brand-new black hole.
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