{"id":9632,"date":"2023-11-28T12:03:12","date_gmt":"2023-11-28T16:03:12","guid":{"rendered":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/nasas-fermi-mission-nets-300-gamma-ray-pulsars-and-counting\/"},"modified":"2023-11-28T12:03:12","modified_gmt":"2023-11-28T16:03:12","slug":"nasas-fermi-mission-nets-300-gamma-ray-pulsars-and-counting","status":"publish","type":"post","link":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/nasas-fermi-mission-nets-300-gamma-ray-pulsars-and-counting\/","title":{"rendered":"NASA\u2019s Fermi Mission Nets 300 Gamma-Ray Pulsars \u2026 and Counting"},"content":{"rendered":"

NASA\u2019s Fermi Mission Nets 300 Gamma-Ray Pulsars \u2026 and Counting<\/h2>\n

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7 min read<\/p>\n

NASA\u2019s Fermi Mission Nets 300 Gamma-Ray Pulsars \u2026 and Counting<\/h1>\n<\/div>\n<\/div>\n<\/div>\n

A new catalog produced by a French-led international team of astronomers shows that NASA\u2019s Fermi Gamma-ray Space Telescope<\/a> 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.<\/p>\n

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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\u2019s 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\u2019s Scientific Visualization Studio.<\/a> Credit: NASA\u2019s Goddard Space Flight Center<\/figcaption><\/figure>\n

\u201cPulsars touch on a wide range of astrophysics research, from cosmic rays and stellar evolution to the search for gravitational waves and dark matter,\u201d said study coordinator David Smith, research director at the Bordeaux Astrophysics Laboratory<\/a> in Gironde, France, which is part of CNRS<\/a> (the French National Center for Scientific Research). \u201cThis new catalog compiles full information on all known gamma-ray pulsars in an effort to promote new avenues of exploration.\u201d<\/p>\n

The catalog<\/a> was published on Monday, Nov. 27, in The Astrophysical Journal Supplement.<\/p>\n

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Narrow beams of energy emerge from hot spots on the surface of a neutron star in this artist\u2019s concept. When one of these beams sweeps past Earth, astronomers detect a pulse of light. Credit: NASA\u2019s Goddard Space Flight Center Conceptual Image Lab<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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<\/a>. They possess strong magnetic fields, produce streams of energetic particles, and spin quickly \u2013 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.<\/p>\n

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.<\/p>\n

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More than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way.<\/span><\/h2>\n<\/div>\n
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\"Elizabeth<\/figure>\n<\/div>\n
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Elizabeth Hays<\/p>\n

Fermi Project Scientist<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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\u2019s 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<\/a>, the brightest persistent source in the sky for Fermi.<\/p>\n

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\nThis movie shows the Vela pulsar in gamma rays detected by the Large Area Telescope aboard NASA\u2019s Fermi observatory. A single pulsar cycle is repeated. Bluer colors indicate gamma rays with higher energies. Credit: NASA\/DOE\/Fermi LAT Collaboration<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

The Vela pulsar and its famous sibling in the Crab Nebula<\/a> 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.<\/p>\n

The Old and the Restless<\/strong><\/h2>\n

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.<\/p>\n

Thanks to a great combination of gamma-ray brightness and smooth spin slowdown, the MSP J1231-1411 is an ideal \u201ctimer\u201d 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<\/a> \u2013 ripples in space-time \u2013 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.<\/p>\n

\u201cBefore Fermi, we didn\u2019t 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,\u201d said co-author Lucas Guillemot, an associate astronomer at the Laboratory of Physics and Chemistry of the Environment and Space<\/a> and the University of Orleans, France.<\/p>\n

Along Come the Spiders<\/strong><\/h2>\n

The presence of MSPs in binary systems offers a clue to understanding the age-spin paradox. Left to itself, a pulsar\u2019s 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.<\/p>\n

\u201cSpider\u201d systems offer a glimpse of what happens next. They\u2019re classified as redbacks or black widows <\/a>\u2013 named for spiders known for consuming their mates. Black widows have light companions (less than about 5% of the Sun\u2019s mass), while redbacks have heavier partners. As the pulsar spins up, its emissions and particle outflows become so invigorated that \u2013 through processes still poorly understood \u2013 it heats and slowly evaporates its companion. The most energetic spiders may fully evaporate their partners, leaving only an isolated MSP behind.<\/p>\n

J1555-2908 is a black widow with a surprise \u2013 its gravitational web may have ensnared a passing planet<\/a>. An analysis of 12 years of Fermi data reveals long-term spin variations much larger than those seen in other MSPs. \u201cWe 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,\u201d said co-author Colin Clark, a research group leader at the Max Planck Institute for Gravitational Physics<\/a> in Hannover, Germany.<\/p>\n

Other curious binaries include the so-called transitional pulsars,<\/a> 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.<\/p>\n

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This artist\u2019s concept illustrates a possible model for the transitional pulsar J1023. When astronomers can detect pulses in radio (green), the pulsar\u2019s energetic outflow holds back its companion\u2019s 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\u2019s Goddard Space Flight Center<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

Some pulsars don\u2019t require a partner to switch things up. J2021+4026, a young, isolated pulsar located about 4,900 light-years away, underwent a puzzling \u201cmode change\u201d 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\u2018s magnetic field.<\/p>\n

Farther afield, Fermi discovered the first gamma-ray pulsar in another galaxy<\/a>, the neighboring Large Magellanic Cloud, in 2015. And in 2021, astronomers announced the discovery of a giant gamma-ray flare<\/a> from a different type of neutron star (called a magnetar) located in the Sculptor galaxy, about 11.4 million light-years away.<\/p>\n

\u201cMore than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way,\u201d said Elizabeth Hays, the mission\u2019s project scientist at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.<\/p>\n

Explore the Fermi gamma-ray pulsar catalog on WorldWide Telescope<\/a><\/p>\n

Max Planck Institute release<\/a><\/p>\n

By Francis Reddy<\/a>
NASA\u2019s Goddard Space Flight Center<\/a>, Greenbelt, Md.<\/strong><\/p>\n

Media contact:
Claire Andreoli<\/a>
claire.andreoli@nasa.gov<\/a>
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.
(301) 286-1940<\/strong><\/p>\n

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