{ "id": 10943, "url": "https://svs.gsfc.nasa.gov/10943/", "page_type": "Produced Video", "title": "Fermi Observations of Dwarf Galaxies Provide New Insights on Dark Matter", "description": "There's more to the cosmos than meets the eye. About 80 percent of the matter in the universe is invisible to telescopes, yet its gravitational influence is manifest in the orbital speeds of stars around galaxies and in the motions of clusters of galaxies. Yet, despite decades of effort, no one knows what this \"dark matter\" really is. Many scientists think it's likely that the mystery will be solved with the discovery of new kinds of subatomic particles, types necessarily different from those composing atoms of the ordinary matter all around us. The search to detect and identify these particles is underway in experiments both around the globe and above it. Scientists working with data from NASA's Fermi Gamma-ray Space Telescope have looked for signals from some of these hypothetical particles by zeroing in on 10 small, faint galaxies that orbit our own. Although no signals have been detected, a novel analysis technique applied to two years of data from the observatory's Large Area Telescope (LAT) has essentially eliminated these particle candidates for the first time.WIMPs, or Weakly Interacting Massive Particles, represent a favored class of dark matter candidates. Some WIMPs may mutually annihilate when pairs of them interact, a process expected to produce gamma rays — the most energetic form of light — that the LAT is designed to detect. The team examined two years of LAT-detected gamma rays with energies in the range from 200 million to 100 billion electron volts (GeV) from 10 of the roughly two dozen dwarf galaxies known to orbit the Milky Way. Instead of analyzing the results for each galaxy separately, the scientists developed a statistical technique — they call it a \"joint likelihood analysis\" — that evaluates all of the galaxies at once without merging the data together. No gamma-ray signal consistent with the annihilations expected from four different types of commonly considered WIMP particles was found.For the first time, the results show that WIMP candidates within a specific range of masses and interaction rates cannot be dark matter. A paper detailing these results appeared in the Dec. 9, 2011, issue of Physical Review Letters. || ", "release_date": "2012-04-02T12:30:00-04:00", "update_date": "2024-10-10T00:15:59.099603-04:00", "main_image": { "id": 477680, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a010900/a010943/test__left_00999.jpg", "filename": "test__left_00999.jpg", "media_type": "Image", "alt_text": "No one knows what dark matter is, but it constitutes 80 percent of the matter in our universe. By studying numerous dwarf galaxies — satellite systems that orbit our own Milky Way galaxy — NASA's Fermi Gamma-ray Space Telescope has produced some of the strongest limits yet on the nature of the hypothetical particles suspected of making up dark matter. Short, narrated video.Poster image, and dark matter simulations credit: Simulation: Wu, Hahn, Wechsler, Abel(KIPAC), Visualization: Kaehler (KIPAC)Watch this video on the NASAexplorer YouTube channel.For complete transcript, click here.", "width": 1920, "height": 1080, "pixels": 2073600 }, "main_video": null, "main_credits": { "Visualizations by": [ { "name": "Scott Wiessinger", "employer": "USRA" } ] }, "progress": "Complete", "media_groups": [ { "id": 349589, "url": "https://svs.gsfc.nasa.gov/10943/#media_group_349589", "widget": "Basic text with HTML", "title": "", "caption": "", "description": "There's more to the cosmos than meets the eye. About 80 percent of the matter in the universe is invisible to telescopes, yet its gravitational influence is manifest in the orbital speeds of stars around galaxies and in the motions of clusters of galaxies. Yet, despite decades of effort, no one knows what this \"dark matter\" really is. Many scientists think it's likely that the mystery will be solved with the discovery of new kinds of subatomic particles, types necessarily different from those composing atoms of the ordinary matter all around us. The search to detect and identify these particles is underway in experiments both around the globe and above it.

Scientists working with data from NASA's Fermi Gamma-ray Space Telescope have looked for signals from some of these hypothetical particles by zeroing in on 10 small, faint galaxies that orbit our own. Although no signals have been detected, a novel analysis technique applied to two years of data from the observatory's Large Area Telescope (LAT) has essentially eliminated these particle candidates for the first time.

WIMPs, or Weakly Interacting Massive Particles, represent a favored class of dark matter candidates. Some WIMPs may mutually annihilate when pairs of them interact, a process expected to produce gamma rays — the most energetic form of light — that the LAT is designed to detect.

The team examined two years of LAT-detected gamma rays with energies in the range from 200 million to 100 billion electron volts (GeV) from 10 of the roughly two dozen dwarf galaxies known to orbit the Milky Way. Instead of analyzing the results for each galaxy separately, the scientists developed a statistical technique — they call it a \"joint likelihood analysis\" — that evaluates all of the galaxies at once without merging the data together. No gamma-ray signal consistent with the annihilations expected from four different types of commonly considered WIMP particles was found.

For the first time, the results show that WIMP candidates within a specific range of masses and interaction rates cannot be dark matter. A paper detailing these results appeared in the Dec. 9, 2011, issue of Physical Review Letters.", "items": [], "extra_data": {} }, { "id": 349590, "url": "https://svs.gsfc.nasa.gov/10943/#media_group_349590", "widget": "Video player", "title": "", "caption": "", "description": "No one knows what dark matter is, but it constitutes 80 percent of the matter in our universe. By studying numerous dwarf galaxies — satellite systems that orbit our own Milky Way galaxy — NASA's Fermi Gamma-ray Space Telescope has produced some of the strongest limits yet on the nature of the hypothetical particles suspected of making up dark matter. Short, narrated video.

Poster image, and dark matter simulations credit: Simulation: Wu, Hahn, Wechsler, Abel(KIPAC), Visualization: Kaehler (KIPAC)

Watch this video on the NASAexplorer YouTube channel.

For complete transcript, click here.", "items": [ { "id": 322139, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 477680, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a010900/a010943/test__left_00999.jpg", "filename": "test__left_00999.jpg", "media_type": "Image", "alt_text": "No one knows what dark matter is, but it constitutes 80 percent of the matter in our universe. By studying numerous dwarf galaxies — satellite systems that orbit our own Milky Way galaxy — NASA's Fermi Gamma-ray Space Telescope has produced some of the strongest limits yet on the nature of the hypothetical particles suspected of making up dark matter. 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Dark matter, after all, is the invisible glue that makes up the bulk of the universe’s contents. All galaxies are dominated by it; in fact, galaxies are thought to form inside immense halos of dark matter. So, finding a galaxy lacking the invisible stuff is an extraordinary claim that challenges conventional wisdom. It would have the potential to upset theories of galaxy formation and evolution.For more information, visit https://nasa.gov/hubble. Additional Visualizations:Galaxy Motion Simulation: Credit: ESO/L. Calçada.Dark Matter Simulation: Credit: Additional Visualizations:Galaxy Motion Simulation: Credit: ESO/L. Calçada.Dark Matter Simulation: Credit: Wu, Hahn, Wechsler, Abel(KIPAC), Visualization: Kaehler (KIPAC)Music Credits: \"Aphelion Horizon\" by Alistair Hetherington [PRS] via Atmosphere Music Ltd. [PRS], and Universal Production Music. || ", "release_date": "2021-06-17T10:55:00-04:00", "update_date": "2023-05-03T13:44:05.990934-04:00", "main_image": { "id": 378225, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a013800/a013872/13872_DARK_MAIN_WIDE_PRINT.jpg", "filename": "13872_DARK_MAIN_WIDE_PRINT.jpg", "media_type": "Image", "alt_text": "Master VersionHorizontal version. This is for use on any YouTube or non-YouTube platform where you want to display the video horizontally.", "width": 1920, "height": 1080, "pixels": 2073600 } }, { "id": 12907, "url": "https://svs.gsfc.nasa.gov/12907/", "page_type": "Produced Video", "title": "Hubble Views a Galaxy Lacking Dark Matter", "description": "NASA's Hubble Space Telescope took an image of a bizarre, ghostly looking galaxy called NGC 1052-DF2 that astronomers calculate to have little to no dark matter. This is the first galaxy astronomers have discovered to be so lacking in dark matter, which is thought to comprise 85% of our universe's mass.Read the full story at nasa.gov.Download the release images at HubbleSite.org.Find the science paper at nature.com. || ", "release_date": "2018-03-28T12:55:00-04:00", "update_date": "2023-05-03T13:46:55.290996-04:00", "main_image": { "id": 405412, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a012900/a012907/hubble_galaxy_without_dark_matter_thumbnail.png", "filename": "hubble_galaxy_without_dark_matter_thumbnail.png", "media_type": "Image", "alt_text": "Watch this video on the NASA Goddard YouTube channel.Music credit: \"Reborn\" by Maksim Tyutmanov [PRS] and Victoria Beits [PRS]; Atmosphere Music Ltd PRS; Score Addiction; Killer Tracks Production Music", "width": 1920, "height": 1080, "pixels": 2073600 } }, { "id": 12317, "url": "https://svs.gsfc.nasa.gov/12317/", "page_type": "Produced Video", "title": "NASA's Fermi Mission Broadens its Dark Matter Search", "description": "Top: Gamma rays (magenta lines) coming from a bright source like NGC 1275 in the Perseus galaxy cluster should form a particular type of spectrum (right). Bottom: Gamma rays convert into hypothetical axion-like particles (green dashes) and back again when they encounter magnetic fields (gray curves). The resulting gamma-ray spectrum (lower curve at right) would show unusual steps and gaps not seen in Fermi data, which means a range of these particles cannot make up a portion of dark matter.Credit: SLAC National Accelerator Laboratory/Chris Smith || ALP_2_sequences.gif (1074x580) [211.8 KB] || ", "release_date": "2016-08-12T13:00:00-04:00", "update_date": "2023-05-03T13:48:24.423680-04:00", "main_image": { "id": 421560, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a012300/a012317/smc_dm_split.jpg", "filename": "smc_dm_split.jpg", "media_type": "Image", "alt_text": "The Small Magellanic Cloud (SMC), at center, is the second-largest satellite galaxy orbiting our own. This image superimposes a photograph of the SMC with one half of a model of its dark matter (right of center). Lighter colors indicate greater density and show a strong concentration toward the galaxy's center. Ninety-five percent of the dark matter is contained within a circle tracing the outer edge of the model shown. In six years of data, Fermi finds no indication of gamma rays from the SMC's dark matter.Credits: Dark matter, R. Caputo et al. 2016; background, Axel Mellinger, Central Michigan University", "width": 1920, "height": 1024, "pixels": 1966080 } }, { "id": 11513, "url": "https://svs.gsfc.nasa.gov/11513/", "page_type": "Produced Video", "title": "Fermi Hints at Dark Matter", "description": "Using public data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory, Harvard University, MIT and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter. No one knows the true nature of dark matter, but WIMPs, or Weakly Interacting Massive Particles, represent a leading class of candidates. Theorists have envisioned a wide range of WIMP types, some of which may either mutually annihilate or produce an intermediate, quickly decaying particle when they collide. Both of these pathways end with the production of gamma rays — the most energetic form of light — at energies within the detection range of Fermi's Large Area Telescope (LAT).The galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas. It's also where astronomers expect to find the galaxy's highest density of dark matter, which only affects normal matter and radiation through its gravity. Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built. When the astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains. This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) — roughly a billion times greater than that of visible light — and extends outward at least 5,000 light-years from the galactic center. The researchers find these features difficult to reconcile with other explanations proposed, such as undiscovered pulsars. The gamma-ray spectrum of the excess, its symmetry around the galactic center and its overall brightness, is, however, consistent with annihilations of dark matter particles in the mass range of 31 and 40 GeV. The scientists note that discoveries in other astronomical objects, such as dwarf galaxies, and experiments on Earth designed to directly detect dark matter particles will be needed to confirm this interpretation. 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