E and B Experiment (EBEX)

EBEX will measure or obtain an upper limit on the primordial gravity wave generated B-mode amplitude which has not yet been observed. The current experimental upper limit on the T/S ratio, the ratio of the tensor, or B-mode, signal to scalar, or E-mode, signal, is 0.5. EBEX will obtain a high signal to noise detection of the B-mode signal as long as T/S is no smaller than 0.1. If T/S is smaller than 0.1, EBEX will be able to provide an upper limit on T/S down to 0.03 to 2σ. The significance of measuring, or setting an upper limit on, the primordial B-mode signal is that detection of this B-mode signal will set a value for, or an upper limit on, the energy scale of inflation. Since the B-mode signal is the most direct probe of the inflation field, its significance is paramount in understanding if and how inflation occurred. Additionally, CMB polarization promises a look at the inflationary period not possible from other current generation experiments.

EBEX will attempt to detect the lensing of the CMB. The CMB lensing signal is expected to be strong at smaller angular scales; if the amplitude of the signal is as expected, EBEX will constrain the lensing amplitude within 4%. The CMB lensing signal will lead to a better understanding the distribution of matter in the universe, complementing the results from experiments like Sunyaev-Zel’dovich and other non-CMB galaxy cluster surveys as well as large-scale galaxy weak lensing surveys. In addition to acting as a probe for the matter distribution, the lensing signal has bearing on the detection of the primordial B-mode signal at small angular scales where the lensing signal is predicted to dwarf the primordial B-mode signal; a precise understanding of the lensing signal will allow it to be subtracted from the B-mode signal, although this is expected to be a non-trivial process. On the other hand, if the predictions about the strength of the lensing signal are incorrect and the signal is smaller than expected resulting in a no detection for EBEX, this result would also be significant in that it would suggest a need to rethink certain assumptions in the distribution of matter in the universe and our models of the evolution of the universe.

EBEX’s position at high altitude in the earth’s atmosphere will allow it to characterize dust and other foreground contaminants that have previously not been well studied at the EBEX frequency bands. An understanding of the levels and distribution of foreground emission, primarily from galactic dust, will be essential in the success of future high altitude or satellite experiments where the CMB is observed at these frequencies; this knowledge will be particularly useful in calibration and subtraction of foregrounds.

EBEX will measure the E-mode polarization to higher precision than previous experiments. The E-mode data will help us better constrain or interpret the results we obtain from other CMB experiments such as the temperature anisotropy data and non-CMB experiments such as supernovae data by providing an independent measurement of similar parameters or breaking the degeneracies present in determining the values of cosmological parameters such as Ω_dm, Ω_b, Ω_Λ.

Go to the official EBEX page here.

For a list of EBEX collaborators, click here.

EBEX Internal Site here.