http://www.newscientist.com/article/mg22429894.500-monster-neutrino-solves-cosmicray-mystery.html#.VC0yuyldW9s

A  COSMIC  coincidence  could  be  the  first  clue  to  the  origin  of  a  high-­energyneutrino  spotted  in  Antarctica  –  and  may  help  pinpoint  the  source  of  high-­energy  cosmic  rays  that  bombard  Earth's  atmosphere.

Cosmic  rays  are  massive  charged  particles  that  barrel  through  deep  space  withenergies  that  dwarf  those  achieved  at  particle  accelerators  on  Earth.  Somemay  be  accelerated  to  such  high  speeds  by  supernovas,  but  others  havemysterious  roots.

"The  origin  of  cosmic  rays  is  one  of  the  most  intriguing  questions  inastrophysics,"  says  Toshihiro  Fujii  at  the  University  of  Chicago.  But  becausethey  can  be  deflected  by  magnetic  fields,  their  sources  are  difficult  to  trace.

On  the  other  hand,  chargeless  and  nearly  massless  particles  called  neutrinos  –a  by-­product  of  the  processes  that  create  cosmic  rays  –  go  direct,  travelling  in  astraight  line  to  Earth  from  their  source.  This  directness  could  make  neutrinosthe  key  to  solving  the  cosmic  ray  puzzle.

Now  astronomers  may  have  observations  to  prove  it.  A  new  study  reports  aconnection  between  a  gigantic  burst  of  energy  at  the  core  of  the  Milky  Way  andneutrino  strikes  on  Earth.

Amy  Barger  at  the  University  of  Wisconsin-­Madison  and  her  colleagues  notethat  on  9  February  2012,  the  Chandra  space  telescope  saw  a  spike  in  X-­rayemissions  from  the  centre  of  our  galaxy,  where  a  supermassive  black  hole  isthought  to  be  surrounded  by  a  maelstrom  of  particles.

Three  hours  later  –  just  long  enough  for  some  of  those  particles  to  havedecayed  into  neutrinos  –  an  array  of  sensors  buried  in  Antarctic  ice,  calledIceCube,  saw  one  of  the  highest-­energy  neutrinos  ever  detected  coming  fromthe  direction  of  the  galactic  centre  (Physical  Review  D,  doi.org/v3p).  Thiscoincidence  suggests  that  this  neutrino,  and  probably  lots  more,  was  produced

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Source  of  the  fast  and  furious?  (Image:NASA/CXC/UMass/D.  Wang  et  al)

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Monster  neutrino  solves  cosmic-­ray  mystery

01  October  2014  by  Hal  HodsonMagazine  issue  2989.  Subscribe  and  save

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10/2/2014 Monster neutrino solves cosmic-ray mystery - space - 01 October 2014 - New Scientist

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near  the  centre  of  the  galaxy.

"This  will  be  the  first  source  of  high-­energy  neutrinos  ever  detected,"  says  LuisAnchordoqui  at  City  University  of  New  York,  who  wasn't  involved  in  the  study."They  have  only  one  precise  correlation,  but  there  are  not  many  objects  in  thegalaxy  that  can  accelerate  particles  like  this."

If  future  observations  confirm  that  neutrinos  are  accelerated  to  high  energies  byactivity  at  the  galactic  centre,  the  same  source  could  explain  high-­energycosmic  rays  –  although  it's  still  unclear  exactly  how  the  accelerator  works.Measuring  the  full  range  of  energies  of  similar  neutrinos  will  help  calculate  thepower  of  the  accelerator  that  kicked  them  across  the  galaxy.  "We  are  notimmediately  going  to  be  able  to  say  what's  going  on  there,  but  it's  the  first  stepto  doing  that,"  says  Anchordoqui.

Meanwhile,  other  observations  suggest  cosmic  rays  may  come  from  evenfurther  afield.  In  August,  Fujii  and  his  colleagues  observed  correlationsbetween  cosmic  rays  detected  at  The  Telescope  Array  in  Utah  and  otherneutrinos  spotted  at  IceCube.  The  source,  based  on  their  paths,  seemed  to  beoutside  the  galaxy.

This  article  appeared  in  print  under  the  headline  "Super-­neutrino  key  to  cosmicray  puzzle"

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10/2/2014 Monster neutrino solves cosmic-ray mystery - space - 01 October 2014 - New Scientist

http://www.newscientist.com/article/mg22429894.500-monster-neutrino-solves-cosmicray-mystery.html#.VC0yuyldW9s 2/3

New  Scientist

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New  Scientist  magazine  delivered  every  week

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near  the  centre  of  the  galaxy.

"This  will  be  the  first  source  of  high-­energy  neutrinos  ever  detected,"  says  LuisAnchordoqui  at  City  University  of  New  York,  who  wasn't  involved  in  the  study."They  have  only  one  precise  correlation,  but  there  are  not  many  objects  in  thegalaxy  that  can  accelerate  particles  like  this."

If  future  observations  confirm  that  neutrinos  are  accelerated  to  high  energies  byactivity  at  the  galactic  centre,  the  same  source  could  explain  high-­energycosmic  rays  –  although  it's  still  unclear  exactly  how  the  accelerator  works.Measuring  the  full  range  of  energies  of  similar  neutrinos  will  help  calculate  thepower  of  the  accelerator  that  kicked  them  across  the  galaxy.  "We  are  notimmediately  going  to  be  able  to  say  what's  going  on  there,  but  it's  the  first  stepto  doing  that,"  says  Anchordoqui.

Meanwhile,  other  observations  suggest  cosmic  rays  may  come  from  evenfurther  afield.  In  August,  Fujii  and  his  colleagues  observed  correlationsbetween  cosmic  rays  detected  at  The  Telescope  Array  in  Utah  and  otherneutrinos  spotted  at  IceCube.  The  source,  based  on  their  paths,  seemed  to  beoutside  the  galaxy.

This  article  appeared  in  print  under  the  headline  "Super-­neutrino  key  to  cosmicray  puzzle"

Recommended  by

If  you  would  like  to  reuse  any  content  from  New  Scientist,  either  in  print  or  online,  pleasecontact  the  syndication  department  first  for  permission.  New  Scientist  does  not  own  rightsto  photos,  but  there  are  a  variety  of  licensing  options  available  for  use  of  articles  and  graphicswe  own  the  copyright  to.

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20:00  28  September  2014Intergalactic  visitorsthreaten  to  bring  chaos  toour  electronic  world.  Isthere  anything  we  can  do?

see  all  related  stories

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http://www.newscientist.com/article/mg22429894.500-monster-neutrino-solves-cosmicray-mystery.html#.VC0yuyldW9s

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