The Cosmic Microwave Background


S P I D E R: Six Eyes in the Sky

The cosmic microwave background (CMB) is the literal afterglow of the Big Bang: a snapshot of our Universe a mere 400,000 years after its birth.  The tiny variations in its brightness and polarization across the sky encode unique information about the composition and history of the cosmos, and have proven to be one of the most powerful tools in modern cosmology.

The CMB is slightly polarized due to Thomson scattering at the epoch of its emission.  A “curl-only” B-mode pattern in this polarization at few-degree angular scales would be a “smoking gun” signature that the universe began with an inflationary period of rapid expansion, and give us a hint of fundamental physics at energies inaccessible at accelerators.  I collaborate on several cutting-edge instruments specifically designed to target this signature in the millimeter-wave sky using massively-multiplexed arrays of superconducting detectors developed at Caltech/JPL.

Planck (2013)

SPIDER is an ambitious balloon-borne instrument to measure the polarization of the CMB with unprecedented precision.  SPIDER will fly on a long-duration balloon flight from McMurdo Station, Antarctica, to make multi-band polarization maps at large angular scales. Its maps  will yield strong constraints on inflation, as well as serving as a technology pathfinder for future space missions. 

I lead the receiver team for SPIDER at Caltech, which has built and characterized the six receivers for the SPIDER payload.  In flight SPIDER’s 2400 detectors will constitute the most sensitive (lowest noise) CMB receiver yet built.

After a pre-flight integration in Palestine, TX, SPIDER was deployed to Antarctica this fall for its first flight in December 2013.  The 2013/14 balloon campaign was cancelled, however, due to the logistical challenges caused by the October government shutdown.  After a second integration campaign in Princeton, SPIDER reached the ice for the 2014/15 LDB season and launched successfully on January 1, 2015 (see video).

In Fall 2014 there was a brief article on our project in Scientific American.

BICEP2 / Keck Array / BICEP3: The View from the Ground

I also collaborate on a sequence of ground-based instruments deploying similar detector technology. Data from the first two of these instruments is currently under analysis, and BICEP3 is being integrated at the South Pole.

  1. BICEP2: a single 150 GHz telescope (512 detectors) operated at the South Pole from 2009-2012.  In March 2014 BICEP2 reported a detection of B-mode polarization at degree angular scales, pushing the field into new regimes of sensitivity.

  1. The Keck Array: A modular array of five BICEP2-style telescopes (2560 detectors) on the DASI mount, operating at Pole since the 2010/11 austral summer.  Keck currently observes at 100 and 150 GHz, and will deploy 220 GHz receivers in 2014/15.

  1. BICEP3: A new camera at 100 GHz which will deploy a single focal plane of 2560 detectors to the South Pole in the 2014/15 season.

Keck Array