MSGID: 1:317/3 649e5a90   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
   clocks'    
    Radio telescope observations of Milky Way pulsars reveal spacetime   
   distortions likely caused by enormous gravitational waves rolling through   
   everything in existence    
      
     Date:   
         June 29, 2023   
     Source:   
         National Science Foundation   
     Summary:   
         You can't see or feel it, but everything around you -- including   
         your own body -- is slowly shrinking and expanding. It's the weird,   
         spacetime- warping effect of gravitational waves passing through   
         our galaxy. New results are the first evidence of the gravitational   
         wave background -- a sort of soup of spacetime distortions pervading   
         the entire universe and long predicted to exist by scientists.   
      
      
         Facebook Twitter Pinterest LinkedIN Email   
      
   ==========================================================================   
   FULL STORY   
   ==========================================================================   
   You can't see or feel it, but everything around you -- including   
   your own body -- is slowly shrinking and expanding. It's the weird,   
   spacetime-warping effect of gravitational waves passing through our   
   galaxy, according to a new study by a team of researchers with the   
   U.S. National Science Foundation's NANOGrav Physics Frontiers Center.   
      
   The findings published today in The Astrophysical Journal Letters are   
   from the North American Nanohertz Observatory for Gravitational Waves   
   (NANOGrav), a collaborative team of researchers from more than 50   
   institutions in the U.S.   
      
   and abroad. The team conducted an analysis of burned-out stars known as   
   millisecond pulsars, which rotate hundreds of times per second and emit   
   radio pulses like ticks from highly accurate cosmic clocks. The team   
   discovered what appeared to be variations in the "ticking rate" of such   
   pulsars by comparing observations of more than 60 pulsars within radio   
   telescope data spanning 15 years. Their analysis provides evidence that   
   the variations are caused by low- frequency gravitational waves which   
   are distorting the fabric of physical reality known as spacetime.   
      
   According to the NANOGrav team's findings, the spatial distortion   
   from the gravitational waves creates the appearance that the pulsars'   
   radio-signal ticking rates are changing. But really, it's the stretching   
   and squeezing of space between Earth and the pulsars which causes their   
   radio pulses to arrive at Earth billionths of seconds earlier or later   
   than expected. The results are the first evidence of the gravitational   
   wave background -- a sort of soup of spacetime distortions pervading   
   the entire universe and long predicted to exist by scientists.   
      
   "The NSF NANOGrav team created, in essence, a galaxy-wide detector   
   revealing the gravitational waves that permeate our universe," said NSF   
   Director Sethuraman Panchanathan. "The collaboration involving research   
   institutions across the U.S. shows that world-class scientific innovation   
   can, should and does reach every part of our nation."  Gravitational   
   waves were first predicted by Albert Einstein in 1916. They would not be   
   confirmed until 2015, when the Laser Interferometer Gravitational-Wave   
   Observatory (LIGO) detected spacetime ripples passing through the Earth.   
      
   Although the source of those gravitational ripples was a collision of   
   two far- off black holes, the resulting spatial distortion that LIGO   
   detected was smaller than the nucleus of an atom.   
      
   By comparison, the apparent pulsar time shift measured by the NANOGrav   
   team is a few hundred billionths of a second and represents a flexing of   
   spacetime between Earth and the pulsars about the length of a football   
   field. Those spacetime distortions were caused by gravitational waves   
   so immense that the distance between two crests is 2-10 light-years,   
   or about 9-90 trillion kilometers.   
      
   "These are by far the most powerful gravitational waves known to exist,"   
   said West Virginia University astrophysicist Maura McLaughlin, co-director   
   of the NANOgrav Physics Frontiers Center. "Detecting such gargantuan   
   gravitational waves requires a similarly massive detector, and patience."   
   Using 15 years of astronomical data recorded by radio telescopes at NSF-   
   supported observatories -- including Green Bank Observatory in West   
   Virginia, the Very Large Array in Socorro, New Mexico, and Arecibo   
   Observatory in Puerto Rico -- the NANOGrav team created a "detector"   
   of 67 pulsars distributed all across the sky and compared the ticking   
   rate of pairs of those pulsars. Through a sophisticated data analysis,   
   they deduced the presence of the gravitational wave background causing   
   the distortion of space, and thus explained the apparent timing changes   
   of the pulsars.   
      
   This is the first evidence for gravitational waves at these low   
   frequencies," said Vanderbilt University astrophysicist Stephen   
   Taylor, chair of the NANOGrav collaboration and co-leader of the   
   research effort. "The likely source of these waves are distant pairs of   
   close-orbiting, ultra-massive black holes."  "There is so much we have   
   yet to understand about the physical nature of the universe and that's   
   why the National Science Foundation supports daring team efforts like   
   NANOGrav -- to expand our knowledge for the benefit of society," said   
   NSF Assistant Director for Mathematical and Physical Sciences Sean L.   
      
   Jones.   
      
   The team's results are providing new insights into how galaxies evolve   
   and how supermassive black holes grow and merge. The widespread spacetime   
   distortion revealed in their findings implies that extremely massive pairs   
   of black holes may be similarly widespread across the universe, numbering   
   perhaps in the hundreds of thousands or even millions. Eventually, the   
   NANOGrav team expects to be able to identify specific supermassive black   
   hole pairs by tracing the gravitational waves they emit. They may even   
   uncover traces of gravitational waves from the very early universe.   
      
   "While our early data told us that we were hearing something, we now   
   know that it's the music of the gravitational universe," said NANOGrav   
   co-director and Oregon State University astrophysicist Xavier Siemens. "As   
   we keep listening, individual instruments will come to the fore in this   
   cosmic orchestra."   
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Black_Holes # Space_Telescopes # Cosmology #   
                   Astrophysics # Astronomy # Galaxies # Space_Exploration   
                   # Big_Bang   
       * RELATED_TERMS   
             o Gravitational_wave o General_relativity o   
             Dark_matter o Big_Bang o Holographic_Universe o   
             Cosmic_microwave_background_radiation o Shape_of_the_Universe   
             o Extraterrestrial_life   
      
   ==========================================================================   
   Story Source: Materials provided by National_Science_Foundation. Original   
   written by Jason Stoughton. Note: Content may be edited for style   
   and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven   
         Arzoumanian, Paul T. Baker, Bence Be'csy, Laura Blecha, Adam   
         Brazier, Paul R. Brook, Sarah Burke-Spolaor, Rand Burnette, Robin   
         Case, Maria Charisi, Shami Chatterjee, Katerina Chatziioannou,   
         Belinda D. Cheeseboro, Siyuan Chen, Tyler Cohen, James M. Cordes,   
         Neil J. Cornish, Fronefield Crawford, H. Thankful Cromartie,   
         Kathryn Crowter, Curt J. Cutler, Megan E. DeCesar, Dallas DeGan,   
         Paul B. Demorest, Heling Deng, Timothy Dolch, Brendan Drachler,   
         Justin A. Ellis, Elizabeth C. Ferrara, William Fiore, Emmanuel   
         Fonseca, Gabriel E. Freedman, Nate Garver-Daniels, Peter A.   
      
         Gentile, Kyle A. Gersbach, Joseph Glaser, Deborah C. Good, Kayhan   
         Gu"ltekin, Jeffrey S. Hazboun, Sophie Hourihane, Kristina Islo,   
         Ross J.   
      
         Jennings, Aaron D. Johnson, Megan L. Jones, Andrew R. Kaiser,   
         David L.   
      
         Kaplan, Luke Zoltan Kelley, Matthew Kerr, Joey S. Key, Tonia   
         C. Klein, Nima Laal, Michael T. Lam, William G. Lamb, T. Joseph   
         W. Lazio, Natalia Lewandowska, Tyson B. Littenberg, Tingting Liu,   
         Andrea Lommen, Duncan R.   
      
         Lorimer, Jing Luo, Ryan S. Lynch, Chung-Pei Ma, Dustin R. Madison,   
         Margaret A. Mattson, Alexander McEwen, James W. McKee, Maura A.   
      
         McLaughlin, Natasha McMann, Bradley W. Meyers, Patrick M. Meyers,   
         Chiara M. F. Mingarelli, Andrea Mitridate, Priyamvada Natarajan,   
         Cherry Ng, David J. Nice, Stella Koch Ocker, Ken D. Olum, Timothy   
         T. Pennucci, Benetge B. P. Perera, Polina Petrov, Nihan S. Pol,   
         Henri A. Radovan, Scott M. Ransom, Paul S. Ray, Joseph D. Romano,   
         Shashwat C. Sardesai, Ann Schmiedekamp, Carl Schmiedekamp, Kai   
         Schmitz, Levi Schult, Brent J.   
      
         Shapiro-Albert, Xavier Siemens, Joseph Simon, Magdalena S. Siwek,   
         Ingrid H. Stairs, Daniel R. Stinebring, Kevin Stovall, Jerry   
         P. Sun, Abhimanyu Susobhanan, Joseph K. Swiggum, Jacob Taylor,   
         Stephen R. Taylor, Jacob E.   
      
         Turner, Caner Unal, Michele Vallisneri, Rutger van Haasteren,   
         Sarah J.   
      
         Vigeland, Haley M. Wahl, Qiaohong Wang, Caitlin A. Witt, Olivia   
         Young.   
      
         The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave   
         Background. The Astrophysical Journal Letters, 2023; 951 (1):   
         L8 DOI: 10.3847/2041-8213/acdac6   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230629125650.htm   
      
   --- up 1 year, 17 weeks, 3 days, 10 hours, 50 minutes   
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)   
   SEEN-BY: 15/0 106/201 114/705 123/120 153/7715 218/700 226/30 227/114   
   SEEN-BY: 229/110 112 113 307 317 400 426 428 470 664 700 291/111 292/854   
   SEEN-BY: 298/25 305/3 317/3 320/219 396/45 5075/35   
   PATH: 317/3 229/426