Alexander  Stas  and  Benjamin  Liu  

December  12,  2011  

Due:  Monday,  December  19,  2011  

Astronomy  105  

Professor  Sherman  

 

Learning  More  About  Black  Holes  Through  the  Use  of  X-­‐Ray  Telescopes  

                  Recently,  astronomers  have  noticed  a  gas  cloud  heading  towards  the  center  of  our  

galaxy  with  a  mass,   in  astronomical  terms,  that   is   fairly  small.    Although  astronomers  are  

almost   certain   that   there   is   a   black   hole   at   the   center   of   the   Milky   Way,   this   new  

development  will  affirm  their  suspicions  that  a  super-­‐massive  black  hole  does  exist  there.    

Not  only  does  the  rapid  acceleration  of  this  gas  cloud  help  confirm  this  theory,  but   if   the  

gas  emits  extreme  amounts  of  X-­‐rays,  black  holes  will  be  an  almost  certain  phenomenon  

and   there  will   be   a   very   good   reason   to  believe   that   there   is   one  at   the   center  of   every  

galaxy.     In   2013,   this   gas   cloud   is   going   to   be   heading   right   at   the   black   hole   and   we  

propose  that  the  Chandra  X-­‐ray  Observatory  should  be  focused  entirely  on  capturing  this  

event   to   find   if   there   is  another  way  of  detecting  black  holes,   such  as   through  gas   cloud  

interactions.      (BBC  1)  

                  Black   holes,   lacking   both   size   and   light,   are   almost   impossible   to   detect   in   the  

vastness  of  space.  As  of  now,  the  only  way  to  find  these  “galactic  vacuums”  is  to  find  high-­‐

gravity  binary  star  systems  or  sources  of  extremely  intense  X-­‐ray  radiation.  Even  with  these  

two   methods   of   detection,   the   question   still   lingers:   “Do   black   holes   even   exist?”     To  

further  prove   the  existence  of   these  massive  celestial  objects,   scientists  are  studying   this  

gas  cloud,  which  will  fall  into  the  super-­‐massive  black  hole  in  question.    The  accretion  disk  

that  forms  around  the  black  hole  is  extremely  important  in  astronomy.    As  of  now,  almost  

nothing  is  known  about  this  disk  and  the  recent  news  hopes  to  shed  light  on  this  idea  that  

has  escaped  our  understanding.    If  scientists  were  able  to  construct  an  exact  view  of  what  

the   interactions   between   a   gas   cloud   and   a   black   hole   look   like,   they  would   be   able   to  

extrapolate  this  to  other  galaxies.    For  example,  if  each  phase  of  the  interactions  between  

the  cloud  and  the  black  hole  could  be  determined,  astronomers  would  be  able  to  look  for  

distinctive  patterns  or  stages  in  the  reaction.    Also,  because  of  Earth’s  close  in  proximity  to  

this   black   hole   and   our   ability   to   witness   the   beginning   of   the   collision,   we   have   the  

opportunity   to   get   a   very   high-­‐resolution   picture   of   what   happens   to   matter   that  

approaches  the  Schwarzschild  Radius  of  a  super-­‐massive  black  hole.  (Black  Holes  1)  

            The  Chandra  X-­‐ray  Observatory   is   perfect   for  observing   the   collision  between   the  

gas  cloud  and  the  black  hole,  Sagittarius  A*.    So  far  we  can  only  detect  black  holes  by  the  X-­‐

ray  signature  they  leave,  when  particles  get  extremely  energetic  as  they  fall  into  the  black  

hole,  releasing  x-­‐ray  radiation.    Once  the  gas  collides  with  the  black  hole,  the  gas  releases  

the  attained  kinetic  energy  in  the  form  of  X-­‐ray  radiation.  This  phenomenon  is  best  seen  by  

the  Chandra  Observatory,  having  already  been  used  to  study  the  “eating  behaviors”  of  the  

black  hole  at  the  center  of  our  galaxy.  The  telescope  has  an  angular  resolution  of  0.5  arc  

seconds,   which   is   phenomenal.   In   this   case   there   can   be   no   overkill   in   uses   of   this  

telescope,  as  we  need   to  collect  as  much  data   from  this  unique  event,  as  possible.    Also  

because   the   Chandra   Observatory   is   in   very   high   earth   orbit,   it   can   observe   for   a   long  

period   of   its   65-­‐hour   orbit   around   the   Earth.   This   allows   it   to   provide   us  with   immense  

amounts   of   data   regarding   the   interaction   as   the   gas   cloud   approaches   and   enters   the  

Schwarzschild  Radius.  And   in  conclusion,   the   impending  event  of   the  gas  cloud’s  collision  

with   Sagittarius   A*,   must   be   observed   with   great   detail;   detail   that   the   Chandra  

Observatory  is  primed  to  provide.  (Chandra  1)  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Diagrams  

 

 

The  optics  system  of  the  Chandra  Observatory.  (BBC  1)  

 

 

 

A  simulation  of  the  gas  cloud  being  ripped  apart  and  partially  consumed  by  the  black  hole  

Sagittarius  A*.  (Chandra  1)  

Works  Cited  

"BBC  News  -­‐  Supermassive  Black  Hole  Will  'eat'  Gas  Cloud."  BBC  -­‐  Homepage.  Web.  

15  Dec.  2011.  <http://www.bbc.co.uk/news/science-­‐environment-­‐

16178112>.  

"Black  Holes."  Imagine  The  Universe!  Home  Page.  Web.  13  Dec.  2011.  

<http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html>.  

"Chandra  ::  About  Chandra  ::  Science  Instruments."  Chandra  X-­‐ray  Observatory  -­‐  

NASA's  Flagship  X-­‐ray  Telescope.  Web.  18  Dec.  2011.  

<http://chandra.harvard.edu/about/science_instruments.html>.