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BICEP2 telescope near South Pole Telescope

BICEP2 was the second generation BICEP (Background Imaging of Cosmic Extragalactic Polarization) instrument for astronomy located at Earth's south pole.[1] Featuring a greatly improved focal plane transition edge sensor (TES) bolometer array of 512 sensors (256 pixels) operating at 150 GHz, this 26 cm aperture telescope replaced the BICEP1 instrument, and observed from 2010 to 2012.[2][3]

Reports stated in March 2014 that BICEP have detected B-modes from gravitational waves in the early universe (called primordial gravitational waves). An announcement was made on 17 March 2014 from the Harvard–Smithsonian Center for Astrophysics[4][5][6][7][8] announcing that BICEP2 had detected B-modes at the level of r = 0.20+0.07
, disfavouring the null hypothesis (r = 0) at the level of 7 sigma (5.9σ after foreground subtraction).[2] However, on 19 June 2014, lowered confidence in confirming the cosmic inflation findings was reported.[9][10][11]

The BICEP and Keck Array series of experiments began at the California Institute of Technology in 2002. In collaboration with the Jet Propulsion Laboratory, physicists Andrew Lange, Jamie Bock, Brian Keating, and William Holzapfel began the construction of the BICEP1 telescope which deployed to the Amundsen-Scott South Pole Station in 2005 for a three-season observing run.[12] Immediately after deployment of BICEP1, the team, which now included Caltech postdoctoral fellows John Kovac and Chao-Lin Kuo, among others, began work on BICEP2. The telescope remained the same, but new detectors were inserted into BICEP2 using a completely different technology: a printed circuit board on the focal plane that could filter, process, image, and measure radiation from the cosmic microwave background. BICEP2 was deployed to the South Pole in 2009 to begin its three-season observing run which yielded the detection of B-mode polarization in the cosmic microwave background.

The results were released in March 2014 by the four co-principal investigators of BICEP2: John M. Kovac of the Harvard-Smithsonian Center for Astrophysics; Chao-Lin Kuo of Stanford University; Jamie Bock of the California Institute of Technology; and Clem Pryke of the University of Minnesota.

Alternative interpretation of results[edit]

On June 5, 2014 at a conference of the American Astronomical Society, astronomer David Spergel argued that the B-mode polarization detected by BICEP2 could instead be the result of light scattering off dust between the stars in our Milky Way galaxy.[13]


The BICEP2 detector array under a microscope.
The main properties of the BICEP instruments
Instrument Start End Frequency Resolution Sensors (pixels) Refs
BICEP[14] 2006 2008 100 GHz 0.93° 50 (25) [15][16]
150 GHz 0.60° 48 (24) [15]
BICEP2[17] 2010 2012 150 GHz 0.52° 500 (250) [2]
Keck Array[18] 2011 2011 150 GHz 0.52° 1488 (744) [19][20]
2012 2012 2480 (1240)
2013 1488 (744) [20]
100 GHz 992
BICEP3[21] 2013 95 GHz 0.37° 2560 (1280) [22]

See also[edit]


  1. ^ The BICEP2 CMB polarization experiment 7741. Proceedings of SPIE. 2010. p. 11. doi:10.1117/12.857864. 
  2. ^ a b c The BICEP2 Collaboration (2014). BICEP2 2014 I: Detection of B-mode Polarization at Degree Angular Scales. 
  3. ^ The BICEP2 Collaboration (2014). BICEP2 2014 II: Experiment and Three-year Data Set. 
  4. ^ Staff (17 March 2014). "BICEP2 2014 Results Release". National Science Foundation. Retrieved 18 March 2014. 
  5. ^ Clavin, Whitney (17 March 2014). "NASA Technology Views Birth of the Universe". NASA. Retrieved 17 March 2014. 
  6. ^ Overbye, Dennis (17 March 2014). "Detection of Waves in Space Buttresses Landmark Theory of Big Bang". New York Times. Retrieved 17 March 2014. 
  7. ^ Overbye, Dennis (24 March 2014). "Ripples From the Big Bang". New York Times. Retrieved 24 March 2014. 
  8. ^ "Gravitational waves: have US scientists heard echoes of the big bang?". The Guardian. 2014-03-14. Retrieved 2014-03-14. 
  9. ^ Overbye, Dennis (19 June 2014). "Astronomers Hedge on Big Bang Detection Claim". New York Times. Retrieved 20 June 2014. 
  10. ^ Amos, Jonathan (19 June 2014). "Cosmic inflation: Confidence lowered for Big Bang signal". BBC News. Retrieved 20 June 2014. 
  11. ^ Ade, P.A.R. et al (BICEP2 Collaboration) (19 June 2014). "Detection of B-Mode Polarization at Degree Angular Scales by BICEP2" (PDF). Physical Review Letters 112: 241101. arXiv:1403.3985. Bibcode:2014PhRvL.112x1101A. doi:10.1103/PhysRevLett.112.241101. Retrieved 20 June 2014. 
  12. ^ "NSF Award Abstract #0230438". National Science Foundation. Retrieved 2014-03-26. 
  13. ^ Meg, Urry. "What's behind the Big Bang controversy?". Retrieved 6 June 2014. 
  14. ^ "BICEP1 Collaboration". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  15. ^ a b "BICEP: Robinson Gravitational Wave Background Telescope". Caltech. Retrieved 2014-03-13. 
  16. ^ "W.M. Keck Foundation Gift to Enable Caltech and JPL Scientists to Research the Universe's Violent Origin". Caltech. 
  17. ^ "Collaboration - BICEP2 South Pole". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  18. ^ "Collaboration - Keck Array South Pole". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  19. ^ "Instrument - Keck Array South Pole". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  20. ^ a b "Keck Array South Pole". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  21. ^ "BICEP3 Collaboration". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 
  22. ^ "BICEP3". Harvard–Smithsonian Center for Astrophysics. Retrieved 2014-03-14. 

External links[edit]