Fermi gamma-ray space telescope, the fermi large area telescope (Fermi-Lat) is a gamma-ray experiment installed on the Fermi Gamma-ray Space Telescope. It takes data from 2008 onwards and detects photons in the energy range between 30 mega-electron volts (MeV) and 300 GHz-electron volts (GeV). An artist’s concept of the Fermi Gamma Ray Space Telescope. Unlike experiments on the ground, Fermi-LAT has a much larger area. Image credit: NASA
fermi gamma-ray space telescope
It can see about 20% of the sky at any given time. In study mode, it covers the entire sky in two orbits around the Earth, which takes about 3 hours. The large field of view and near-continuous monitoring of the entire sky make it an ideal tool for studying both continuous sources and sources such as flares and bursts, such as the flow of supermassive black holes in other galaxies, solar and fermi gamma-ray space telescope bursts, stairs.
Fermi-LAT has detected thousands of gamma ray sources in our galaxy and beyond. Most of the sources are active galactic nuclei, supermassive black holes that collect matter and emit jets that point towards us. The LAT has detected more than 200 pulsars in our galaxy, vastly improving our understanding of the physics of these fascinating objects (the previous fermi gamma-ray space telescope, EGRET, detected only 6). Fermi-Let has also made some unexpected discoveries, such as the gamma ray emission from Nova.
In addition to observing point sources, Fermi-LAT has made an excellent measurement of the diffuse emission of gamma rays, most of which comes from the interaction of galactic cosmic rays with interstellar gas and radiation fields. There are also surprising discoveries in diffuse emission, such as giant bubbles above and below the galactic center and an overabundance of gamma ray emission near the galactic center.
Fermi-lat at ECAP: At ECAP we work on the analysis of gamma ray data and the interpretation of large-scale emission components, such as Fermi bubbles and the addition of galactic centers. We also work on data-driven methods for point source analysis, such as waveform transformations. NASA’s large field telescope (LAT) from NASA’s Fermi gamma-ray space telescope, Fermi’s final gamma-ray halo around a nearby pulsar, which is about 800 light years away in a constellation of Gemini.
fermi gamma-ray telescope
A pulsar, a rapidly rotating neutron star, naturally surrounds itself with a cloud of electrons and positrons. The reason for this is that the magnetic field of a neutron star extracts particles from the surface and accelerates them to the speed of light. Electrons and positrons are among the sharp particles known as cosmic rays, which originate beyond the solar system. Because cosmic ray particles carry an electric charge, their paths dislocate when they find a magnetic field on their trip to Earth.
This means that astronomers cannot directly monitor their sources. During the last decade, Farzi aboard the International Space Station, measurements from NASA’s alpha magnetic spectrometer and other space experiments have seen more positrons at higher energies than scientists. Our analysis suggests that Geminga may be responsible for a decade-long puzzle about why positrons are unusually abundant near Earth, said Dr. Matia di Mauro, an astrophysicist at the Catholic University of America and the Flight Center. NASA Goddard space.
To study the halo around Gemminga, Drs. De Mauro and his colleagues had to eliminate all other sources of gamma rays, including the scattering of light produced by cosmic rays, which contained clouds of gas between stars. We explored the data using 10 different models of interstellar emissions, said postdoctoral researcher Dr. Sylvia Manconi of RWTH Aachen University. When these sources were removed, there was a giant.
A huge rectangular glow that spanned about 20 degrees, about 40 times that of a full moon, at an energy of 10 billion electron volts (GEV), and even larger at lower energies. The researchers determined that Gemminga can only be responsible for 20% of the high energy positrons observed by other space experiments. Extending this to the cumulative emission of positrons of all pulsars in our galaxy, the Milky Way, it is clear that pulsars are the best explanation for the observed excess of positrons, he said.
Low energy particles travel well beyond the pulsar before moving to the stars, transferring some of their energy and extending the light to gamma rays. That is why the emission of fermi gamma-ray space telescope or gamma rays covers a large area at low energy, said Fiorenza Donato, an astronomer at the National Institute of Nuclear Physics of Italy and the University of Turin. In addition, the Gemminga halo is partially elongated due to the movement of the pulsar through space.
Dr “Our work demonstrates the importance of studying individual sources to see how they contribute to cosmic rays,” said De Mauro. This is an aspect of the new and exciting field known as multimersal astronomy, where we study the universe using many signals, such as cosmic rays, in addition to light. NASA’s fermi gamma-ray space telescope has discovered a foggy but massive glow of high-energy light around a nearby pulsar. If visible from the human eye, this “halo” of gamma rays will appear about 40 times larger in the sky than the full moon.
This structure can provide a solution to an ancient mystery about the amount of antimatter in our neighborhood. “Our analysis suggests that this same pulsar would explain a riddle of a decade of why a type of cosmic particle is unusually abundant near Earth,” said an astrophysicist at the Catholic University of America in Washington. Said Mattia Di Mauro, physicist and astronomer on NASA’s Goddard Space Flight.
Center in Greenbelt, Maryland
These are positrons, antimatter versions of electrons, that come from somewhere beyond the solar system. An article detailing the findings was published in Physical Review D on December 17 and is available online. A neutron star is the crushed core left behind, when a star more massive than the Sun runs out of fuel, collapses under its own weight and explodes like a supernova. We see some neutron stars like pulsars, objects that emit rapid rays of light that, like the lighthouse, float regularly in our line of sight.
Jeminga (pronounced geo-ming-ga) discovered in 1972 by NASA’s Small Astronomy Satellite 2 is one of the brightest gamma-ray pulsars. This constellation is about 800 light years away in Gemini. Gemminga’s name is a play on words with the phrase “Gemini gamma ray source” and the expression “is not there”, referring to the inability of astronomers to find objects in other energies in the dialect of Milan, Italy. Gemminga was finally identified in March 1991.
When the flashing X-rays extracted by the Rosat mission in Germany showed that the pulsar turned 4.2 seconds. A pulsar is naturally surrounded with a cloud of electrons and positrons. This is because the intense magnetic field of a neutron star extracts particles from the surface of the pulsar and accelerates them almost at the speed of light. Electrons and positrons are among the sharp particles known as cosmic rays. Which originate beyond the solar system.
Because cosmic ray particles carry an electric charge, their paths dislocate when they find a magnetic field on their trip to Earth. This means that astronomers cannot directly monitor their sources. Over the past decade, Farzi aboard the International Space Station, cosmic ray measurements performed by NASA’s Alpha Magnetic Spectrometer (AMS-02) and other space experiments near Earth have seen more positrons at higher energies than the scientists.
Nearby Pulsars like Gemminga were the main suspects. Then, in 2017, scientists from the High Altitude Chernakov Gamma Ray Observatory (HAWC) near Puebla, Mexico, confirmed the surface arrest of a small halo of gamma rays around Jamming. He observed this structure with an energy of 5 to 40 billion volts of electrons, light with many times more energy than our eyes. Scientists believe that this emission occurs when accelerated electrons and positrons collide with near starlight.
The collision increases the light at very high energy. Based on the shape of the halo, the HAWC team concluded that Geminga positrons rarely reach Earth with these energies. If true, this would mean that the observed positron should have a more exotic explanation. But interest in a Pulsar original continued, and Gaminga was in front and center. Di Mauro led a decade-long analysis of Gemminga gamma ray data acquired by Fermi’s Large Area Telescope (LAT).
clouds of gas
Which monitors low energy light compared to HAWC. “To study the halo, we had to eliminate all other sources of gamma rays, including the light that has been diffused since the creation of cosmic rays with clouds of gas cost,” co-author Silvia Manconi, a postdoctoral researcher at the RWTH University of Aachen in Germany. He said: We explore the data using 10 different models of interstellar emissions when these sources were removed.
There was a huge oblique glow that spread about 20 degrees to the sky with an energy of 10 billion electron volts (GeV). It has a shape similar to the famous Big Dipper star pattern, and the halo is even larger at lower energies. Low energy particles travel well beyond the pulsar before moving to the stars, transferring some of their energy and extending the light to gamma rays. That is why gamma irradiation covers a large area with little energy, said Fiorenza Donato at the National Institute of Nuclear Physics of Italy and the University of Turin.
pulsars in galaxy
In addition, the interference halo is partly due to the movement of the pulsar through space. The team determined that Fermi LAT data was consistent with previous observations of HAWC. Geminga can only represent 20% of the high energy positrons observed by the AMS-02 experiment. Extending this to the cumulative emissions of all pulsars in galaxy, scientists say that the Pulsar positron is the best explanation for the excess.
My work demonstrates the importance of studying individual sources to explain how they contribute to cosmic rays, said Di Mauro. This is an aspect of the new and exciting field known as multimersal astronomy, where we study the universe using many signals, such as cosmic rays, in addition to light.