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NASA’s Fermi Mission Nets 300 Gamma-Ray Pulsars … and Counting
A new catalog produced by a French-led international team of astronomers shows that NASA’s Fermi Gamma-ray Space Telescope has discovered 294 gamma-ray-emitting pulsars, while another 34 suspects await confirmation. This is 27 times the number known before the mission launched in 2008.
This visualization shows 294 gamma-ray pulsars, first plotted on an image of the entire starry sky as seen from Earth and then transitioning to a view from above our galaxy. The symbols show different types of pulsars. Young pulsars blink in real time except for the Crab, which pulses slower than in real time because its rate is only slightly lower than the video’s frame rate. Millisecond pulsars remain steady, pulsing too quickly to see. The Crab, Vela, and Geminga were among the 11 gamma-ray pulsars known before Fermi launched. Other notable objects are also highlighted. Distances are shown in light-years (abbreviated ly). Download high-resolution video and images from NASA’s Scientific Visualization Studio. Credit: NASA’s Goddard Space Flight Center “Pulsars touch on a wide range of astrophysics research, from cosmic rays and stellar evolution to the search for gravitational waves and dark matter,” said study coordinator David Smith, research director at the Bordeaux Astrophysics Laboratory in Gironde, France, which is part of CNRS (the French National Center for Scientific Research). “This new catalog compiles full information on all known gamma-ray pulsars in an effort to promote new avenues of exploration.”
The catalog was published on Monday, Nov. 27, in The Astrophysical Journal Supplement.
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Narrow beams of energy emerge from hot spots on the surface of a neutron star in this artist’s concept. When one of these beams sweeps past Earth, astronomers detect a pulse of light. Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab Pulsars are a type of neutron star, the city-sized leftover of a massive sun that has exploded as a supernova. Neutron stars, containing more mass than our Sun in a ball less than 17 miles wide, represent the densest matter astronomers can study directly. They possess strong magnetic fields, produce streams of energetic particles, and spin quickly – 716 times a second for the fastest known. Pulsars, in addition, emit narrow beams of energy that swing lighthouse-like through space as the objects rotate. When one of these beams sweeps past Earth, astronomers detect a pulse of emission.
The new catalog represents the work of 170 scientists across the globe. A dozen radio telescopes carry out regular monitoring of thousands of pulsars, and radio astronomers search for new pulsars within gamma-ray sources discovered by Fermi. Other researchers have teased out gamma-ray pulsars that have no radio counterparts through millions of hours of computer calculation, a process called a blind search.
More than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way.
Fermi Project Scientist
Of the 3,400 pulsars known, most of them observed via radio waves and located within our Milky Way galaxy, only about 10% also pulse in gamma rays, the highest-energy form of light. Visible light has energies between 2 and 3 electron volts. Fermi’s Large Area Telescope can detect gamma rays with billions of times this energy, and other facilities have observed emission thousands of times greater still from the nearby Vela pulsar, the brightest persistent source in the sky for Fermi.
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This movie shows the Vela pulsar in gamma rays detected by the Large Area Telescope aboard NASA’s Fermi observatory. A single pulsar cycle is repeated. Bluer colors indicate gamma rays with higher energies. Credit: NASA/DOE/Fermi LAT Collaboration The Vela pulsar and its famous sibling in the Crab Nebula are young, solitary objects, formed about 11,000 and 970 years ago, respectively. Their emissions arise as their magnetic fields spin through space, but this also gradually slows their rotation. The younger Crab pulsar spins nearly 30 times a second, while Vela clocks in about a third as fast.
The Old and the Restless
Paradoxically, though, pulsars that are thousands of times older spin much faster. One example of these so-called millisecond pulsars (MSPs) is J1824-2452A. It whirls around 328 times a second and, with an age of about 30 million years, ranks among the youngest MSPs known.
Thanks to a great combination of gamma-ray brightness and smooth spin slowdown, the MSP J1231-1411 is an ideal “timer” for use in gravitational wave searches. By monitoring a collection of stable MSPs, astronomers hope to link timing changes to passing low-frequency gravitational waves – ripples in space-time – that cannot be detected by current gravitational observatories. It was discovered in one of the first radio searches targeting Fermi gamma-ray sources not associated with any known counterpart at other wavelengths, a technique that turned out to be exceptionally successful.
“Before Fermi, we didn’t know if MSPs would be visible at high energies, but it turns out they mostly radiate in gamma rays and now make up fully half of our catalog,” said co-author Lucas Guillemot, an associate astronomer at the Laboratory of Physics and Chemistry of the Environment and Space and the University of Orleans, France.
Along Come the Spiders
The presence of MSPs in binary systems offers a clue to understanding the age-spin paradox. Left to itself, a pulsar’s emissions slow it down, and with slower spin its emissions dim. But if closely paired with a normal star, the pulsar can pull a stream of matter from its companion that, over time, can spin up the pulsar.
“Spider” systems offer a glimpse of what happens next. They’re classified as redbacks or black widows – named for spiders known for consuming their mates. Black widows have light companions (less than about 5% of the Sun’s mass), while redbacks have heavier partners. As the pulsar spins up, its emissions and particle outflows become so invigorated that – through processes still poorly understood – it heats and slowly evaporates its companion. The most energetic spiders may fully evaporate their partners, leaving only an isolated MSP behind.
J1555-2908 is a black widow with a surprise – its gravitational web may have ensnared a passing planet. An analysis of 12 years of Fermi data reveals long-term spin variations much larger than those seen in other MSPs. “We think a model incorporating the planet as a third body in a wide orbit around the pulsar and its companion describes the changes a little better than other explanations, but we need a few more years of Fermi observations to confirm it,” said co-author Colin Clark, a research group leader at the Max Planck Institute for Gravitational Physics in Hannover, Germany.
Other curious binaries include the so-called transitional pulsars, such as J1023+0038, the first identified. An erratic stream of gas flowing from the companion to the neutron star may surge, suddenly forming a disk around the pulsar that can persist for years. The disk shines brightly in optical light, X-rays, and gamma rays, but pulses become undetectable. When the disk again vanishes, so does the high-energy light and the pulses return.
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This artist’s concept illustrates a possible model for the transitional pulsar J1023. When astronomers can detect pulses in radio (green), the pulsar’s energetic outflow holds back its companion’s gas stream. Sometimes the stream surges, creating a bright disk around the pulsar that can persist for years. The disk shines brightly in X-rays, and gas reaching the neutron star produces jets that emit gamma rays (magenta), obscuring the pulses until the disk eventually dissipates. Credit: NASA’s Goddard Space Flight Center Some pulsars don’t require a partner to switch things up. J2021+4026, a young, isolated pulsar located about 4,900 light-years away, underwent a puzzling “mode change” in 2011, dimming its gamma rays over about a week and then, years later, slowly returning to its original brightness. Similar behavior had been seen in some radio pulsars, but this was a first in gamma rays. Astronomers suspect the event may have been triggered by crustal cracks that temporarily changed the pulsar‘s magnetic field.
Farther afield, Fermi discovered the first gamma-ray pulsar in another galaxy, the neighboring Large Magellanic Cloud, in 2015. And in 2021, astronomers announced the discovery of a giant gamma-ray flare from a different type of neutron star (called a magnetar) located in the Sculptor galaxy, about 11.4 million light-years away.
“More than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way,” said Elizabeth Hays, the mission’s project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Explore the Fermi gamma-ray pulsar catalog on WorldWide Telescope
Max Planck Institute release
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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The spectacular aurora borealis, or the “northern lights,” over Canada is sighted from the space station near the highest point of its orbital path. The station’s main solar arrays are seen in the left foreground.NASA The aurora borealis adds a bit of flair to our home planet in this image taken from the International Space Station on Sept. 15, 2017. This phenomenon happens because the Sun bathes Earth in a steady stream of energetic particles, magnetic fields and radiation that can stimulate our atmosphere and light up the night sky. When this happens in the Southern Hemisphere, it is called aurora australis.
See how you can help track auroras around the world with the Aurorasaurus project. All you need is a cell phone or laptop.
Image Credit: NASA
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4 Min Read NASA’s Webb Reveals New Features in Heart of Milky Way
Sagitarius C (NIRCam) Credits: NASA, ESA, CSA, STScI, and S. Crowe (University of Virginia). The latest image from NASA’s James Webb Space Telescope shows a portion of the dense center of our galaxy in unprecedented detail, including never-before-seen features astronomers have yet to explain. The star-forming region, named Sagittarius C (Sgr C), is about 300 light-years from the Milky Way’s central supermassive black hole, Sagittarius A*.
Image: Sagitarius C (NIRCam)
The NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope’s reveals a portion of the Milky Way’s dense core in a new light. An estimated 500,000 stars shine in this image of the Sagittarius C (Sgr C) region, along with some as-yet unidentified features. A large region of ionized hydrogen, shown in cyan, contains intriguing needle-like structures that lack any uniform orientation.NASA, ESA, CSA, STScI, and S. Crowe (University of Virginia). “There’s never been any infrared data on this region with the level of resolution and sensitivity we get with Webb, so we are seeing lots of features here for the first time,” said the observation team’s principal investigator Samuel Crowe, an undergraduate student at the University of Virginia in Charlottesville. “Webb reveals an incredible amount of detail, allowing us to study star formation in this sort of environment in a way that wasn’t possible previously.”
“The galactic center is the most extreme environment in our Milky Way galaxy, where current theories of star formation can be put to their most rigorous test,” added professor Jonathan Tan, one of Crowe’s advisors at the University of Virginia.
Amid the estimated 500,000 stars in the image is a cluster of protostars – stars that are still forming and gaining mass – producing outflows that glow like a bonfire in the midst of an infrared-dark cloud. At the heart of this young cluster is a previously known, massive protostar over 30 times the mass of our Sun. The cloud the protostars are emerging from is so dense that the light from stars behind it cannot reach Webb, making it appear less crowded when in fact it is one of the most densely packed areas of the image. Smaller infrared-dark clouds dot the image, looking like holes in the starfield. That’s where future stars are forming.
Webb’s NIRCam (Near-Infrared Camera) instrument also captured large-scale emission from ionized hydrogen surrounding the lower side of the dark cloud, shown cyan-colored in the image. Typically, Crowe says, this is the result of energetic photons being emitted by young massive stars, but the vast extent of the region shown by Webb is something of a surprise that bears further investigation. Another feature of the region that Crowe plans to examine further is the needle-like structures in the ionized hydrogen, which appear oriented chaotically in many directions.
“The galactic center is a crowded, tumultuous place. There are turbulent, magnetized gas clouds that are forming stars, which then impact the surrounding gas with their outflowing winds, jets, and radiation,” said Rubén Fedriani, a co-investigator of the project at the Instituto Astrofísica de Andalucía in Spain. “Webb has provided us with a ton of data on this extreme environment, and we are just starting to dig into it.”
Image: Sagitarius C Features
Approximate outlines help to define the features in the Sagittarius C (Sgr C) region. Astronomers are studying data from NASA’s James Webb Space Telescope to understand the relationship between these features, as well as other influences in the chaotic galaxy center.NASA, ESA, CSA, STScI, Samuel Crowe (UVA) Around 25,000 light-years from Earth, the galactic center is close enough to study individual stars with the Webb telescope, allowing astronomers to gather unprecedented information on how stars form, and how this process may depend on the cosmic environment, especially compared to other regions of the galaxy. For example, are more massive stars formed in the center of the Milky Way, as opposed to the edges of its spiral arms?
“The image from Webb is stunning, and the science we will get from it is even better,” Crowe said. “Massive stars are factories that produce heavy elements in their nuclear cores, so understanding them better is like learning the origin story of much of the universe.”
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
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Download full resolution images for this article from the Space Telescope Science Institute.
Piercing the Dark Birthplaces of Massive Stars with Webb
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Webb Mission – https://science.nasa.gov/mission/webb/
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The latest image from the NASA/ESA/CSA James Webb Space Telescope shows a portion of the dense centre of our galaxy in unprecedented detail, including never-before-seen features astronomers have yet to explain. The star-forming region, named Sagittarius C (Sgr C), is about 300 light-years from the Milky Way’s central supermassive black hole, Sagittarius A*.
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5 min read
Joshua Abel: Delivering Roman’s Optical Telescope Assembly On Time, On Target
Joshua Abel’s job as lead systems engineer for the Nancy Grace Roman Space Telescope’s Optical Telescope Assembly is “to deliver the assembly to the Roman observatory on time, within budget, and meeting all the technical requirements.”Credit: NASA / Chris Gunn Name: Joshua Abel
Title: Lead systems engineer for the Roman Space Optical Telescope Assembly
Formal Job Classification: Flight Systems Design Engineer
Organization: Instrument/Payload Systems Engineering Branch (Code 592), Mission Engineering and Systems Analysis Division, Engineering and Technology Directorate
Editor’s note: The Nancy Grace Roman Space Telescope’s Optical Telescope Assembly (OTA) includes the telescope’s primary and secondary mirrors, as well as supporting optics. The OTA enables the telescope to collect light that is then delivered to the observatory instruments.
What do you do and what is most interesting about your role here at Goddard? How do you help support Goddard’s mission?
As the lead systems engineer for the Roman Space Telescope Optical Telescope Assembly, I am the government technical authority for procurement of the assembly, currently being manufactured by L3Harris Corporation in Rochester, New York. I am responsible for technical oversight of the vendor and verifying requirements.
What was your path to becoming an aerospace engineer at Goddard?
In 1999, I received a B.S. in interdisciplinary engineering focused on biomedical engineering from Purdue University. I began a master’s in biomedical engineering in bioheat transfer from Purdue University, but left in 2001 to work at Space Systems/Loral as a thermal systems engineer for satellites.
In 2005, I came to Goddard to work on Hubble Servicing Mission 4 and other NASA satellite servicing projects as a thermal systems engineer. In 2018, I began supporting the New Opportunities Office as a systems engineer, later joining the Instrument/Payload Systems Engineering Branch in my current role.
What are your goals as the lead systems engineer for the Roman Space Telescope Optical Telescope Assembly?
My goal is to deliver the assembly to the Roman observatory on time, within budget, and meeting all the technical requirements. I lead a small team of subject matter experts to review the vendor’s plans and help resolve any technical issues.
What is your management style?
I have a broad engineering background which helps me ask the right questions. I like to build consensus within the team and consolidate everyone’s work into a cohesive and understandable package, communicating complex issues both within the team and to management.
What makes Goddard special?
Everyone here loves their work and is focused on mission success. Even when conversations are difficult and the stakes are high, the emotion comes from caring so deeply. As a systems engineer, my goal is to listen to all ideas and help find the best direction for the project.
Systems engineer Joshua Abel is a team player at work, where he and his team review vendor plans and resolve technical issues for the Roman Space Telescope’s Optical Telescope Assembly, and at home, where he plays and coaches soccer.Courtesy of Joshua Abel What drives you?
I try to do what is needed and contribute to the best of my ability. I am energized when someone says they need help, be it fixing things that are broken or putting new things together. I’m always excited to continue to learn from the our expert team members and vendors.
I prefer working in a team. I like the dynamic environment of systems engineering, which is full of difficult problems that need a larger group to get enough perspectives to solve.
My background and skill mix are a little bit of everything. I enjoy English, communication, math, and science. These interests help me see different sides of a problem.
I like to take things that are slow and repetitive and make them faster and more interesting for myself and others. For example, I like to write Microsoft Excel programs to analyze thermal model data and other large databases to improve productivity.
What advice would you give young engineers?
Take whatever project you are working on and exceed expectations. Don’t be afraid to ask questions. Early tasks for young engineers are not always the most exciting, but work to the best of your ability and try to learn as much as you can. Understand the job and try to see if it can be accomplished better or faster. If you approach every task with this attitude, the next opportunity will always come.
Build your network of experts and use their lessons learned to help your project, always returning that help when you can. Oftentimes the most important piece of knowledge you’ll be able to provide your team is simply knowing who to call to for advice. All of NASA’s engineers are always willing to help.
What are your hobbies?
I play and coach soccer and I also play guitar with my three children around our fire pit. Like every engineer, I’m continually working on home improvement projects for my favorite manager, my wife, who is a thermal systems engineer at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
By Elizabeth M. Jarrell
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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