MSGID: 1:317/3 647ac200   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Mysterious dashes revealed in Milky Way's center    
    Hundreds of horizontal filaments point toward our central supermassive   
   black hole    
      
     Date:   
         June 2, 2023   
     Source:   
         Northwestern University   
     Summary:   
         In the early 1980s, astronomers discovered gigantic, one-dimensional   
         filaments dangling vertically near Sagittarius A*, our galaxy's   
         central supermassive black hole. Now, astronomers have discovered a   
         new population of filaments -- but these threads are much shorter   
         and lie horizontally or radially, spreading out like spokes on a   
         wheel from the black hole.   
      
      
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   FULL STORY   
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   An international team of astrophysicists has discovered something wholly   
   new, hidden in the center of the Milky Way galaxy.   
      
   In the early 1980s, Northwestern University's Farhad Yusef-Zadeh   
   discovered gigantic, one-dimensional filaments dangling vertically   
   near Sagittarius A*, our galaxy's central supermassive black hole. Now,   
   Yusef-Zadeh and his collaborators have discovered a new population of   
   filaments -- but these threads are much shorter and lie horizontally or   
   radially, spreading out like spokes on a wheel from the black hole.   
      
   Although the two populations of filaments share several similarities,   
   Yusef- Zadeh assumes they have different origins. While the vertical   
   filaments sweep through the galaxy, towering up to 150 light-years high,   
   the horizontal filaments look more like the dots and dashes of Morse code,   
   punctuating only one side of Sagittarius A*.   
      
   The study will be published on Friday (June 2) in The Astrophysical   
   Journal Letters.   
      
   "It was a surprise to suddenly find a new population of structures that   
   seem to be pointing in the direction of the black hole," Yusef-Zadeh   
   said. "I was actually stunned when I saw these. We had to do a lot of   
   work to establish that we weren't fooling ourselves. And we found that   
   these filaments are not random but appear to be tied to the outflow of   
   our black hole. By studying them, we could learn more about the black   
   hole's spin and accretion disk orientation. It is satisfying when one   
   finds order in a middle of a chaotic field of the nucleus of our galaxy."   
   An expert in radio astronomy, Yusef-Zadeh is a professor of physics and   
   astronomy at Northwestern's Weinberg College of Arts and Sciences and   
   member of CIERA.   
      
   Decades in the making The new discovery may come as a surprise, but   
   Yusef-Zadeh is no stranger to uncovering mysteries at the center of   
   our galaxy, located 25,000 light-years from Earth. The latest study   
   builds on four decades of his research. After first discovering the   
   vertical filaments in 1984 with Mark Morris and Don Chance, Yusef-Zadeh   
   along with Ian Heywood and their collaborators later uncovered two   
   gigantic radio-emitting bubbles near Sagittarius A*. Then, in a series   
   of publications in 2022, Yusef-Zadeh (in collaborations with Heywood,   
   Richard Arent and Mark Wardle) revealed nearly 1,000 vertical filaments,   
   which appeared in pairs and clusters, often stacked equally spaced or   
   side by side like strings on a harp.   
      
   Yusef-Zadeh credits the flood of new discoveries to enhanced radio   
   astronomy technology, particularly the South African Radio Astronomy   
   Observatory's (SARAO) MeerKAT telescope. To pinpoint the filaments,   
   Yusef-Zadeh's team used a technique to remove the background and smooth   
   the noise from MeerKAT images in order to isolate the filaments from   
   surrounding structures.   
      
   "The new MeerKAT observations have been a game changer," he said. "The   
   advancement of technology and dedicated observing time have given us new   
   information. It's really a technical achievement from radio astronomers."   
   Horizontal vs. vertical After studying the vertical filaments for decades,   
   Yusef-Zadeh was shocked to uncover their horizontal counterparts,   
   which he estimates are about 6 million years old. "We have always been   
   thinking about vertical filaments and their origin," he said. "I'm used   
   to them being vertical. I never considered there might be others along   
   the plane."  While both populations comprise one-dimensional filaments   
   that can be viewed with radio waves and appear to be tied to activities   
   in the galactic center, the similarities end there.   
      
   The vertical filaments are perpendicular to the galactic plane;   
   the horizontal filaments are parallel to the plane but point radially   
   toward the center of the galaxy where the black hole lies. The vertical   
   filaments are magnetic and relativistic; the horizontal filaments appear   
   to emit thermal radiation. The vertical filaments encompass particles   
   moving at speeds near the speed of light; the horizontal filaments   
   appear to accelerate thermal material in a molecular cloud. There are   
   several hundred vertical filaments and just a few hundred horizontal   
   filaments. And the vertical filaments, which measure up to 150 light-years   
   high, far surpass the size of the horizontal filaments, which measure   
   just 5 to 10 light-years in length. The vertical filaments also adorn   
   space around the nucleus of the galaxy; the horizontal filaments appear   
   to spread out to only one side, pointing toward the black hole.   
      
   "One of the most important implications of radial outflow that we have   
   detected is the orientation of the accretion disk and the jet-driven   
   outflow from Sagittarius A* along the galactic plane," Yusef-Zadeh said.   
      
   'Our work is never complete' The new discovery is filled with unknowns,   
   and Yusef-Zadeh's work to unravel its mysteries has just begun. For now,   
   he can only consider a plausible explanation about the new population's   
   mechanisms and origins.   
      
   "We think they must have originated with some kind of outflow from an   
   activity that happened a few million years ago," Yusef-Zadeh said. "It   
   seems to be the result of an interaction of that outflowing material   
   with objects near it. Our work is never complete. We always need to make   
   new observations and continually challenge our ideas and tighten up our   
   analysis."  The study, "The population of the galactic center filaments:   
   Position angle distribution reveal a degree-scale collimated outflow   
   from Sgr A* along the galactic plane," was supported by NASA (award   
   number 80GSFC21M0002). The SARAO is a facility of the National Research   
   Foundation, an agency of the Department of Science and Innovation.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Galaxies # Black_Holes # Astronomy # Astrophysics #   
                   Space_Telescopes # Space_Exploration # Cosmic_Rays # Sun   
       * RELATED_TERMS   
             o Spitzer_space_telescope o Holographic_Universe o Black_hole   
             o Uranus'_natural_satellites o Extrasolar_planet o Galaxy o   
             Andromeda_Galaxy o Large-scale_structure_of_the_cosmos   
      
   ==========================================================================   
   Story Source: Materials provided by Northwestern_University. Original   
   written by Amanda Morris. Note: Content may be edited for style and   
   length.   
      
      
   ==========================================================================   
   Related Multimedia:   
       * MeerKAT_image_with_short_filaments   
   ==========================================================================   
   Journal Reference:   
      1. F. Yusef-Zadeh, R. G. Arendt, M. Wardle, I. Heywood. The   
      Population of   
         the Galactic Center Filaments: Position Angle Distribution Reveals   
         a Degree-scale Collimated Outflow from Sgr A* along the Galactic   
         Plane. The Astrophysical Journal Letters, 2023; 949 (2): L31 DOI:   
         10.3847/2041-8213/ acd54b   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230602115040.htm   
      
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