SPIDER: probing the early Universe with a suborbital polarimeter

Abstract

We evaluate the ability of Spider, a balloon-borne polarimeter, to detect a divergence-free polarization pattern (B-modes) in the cosmic microwave background (CMB). In the inflationary scenario, the amplitude of this signal is proportional to that of the primordial scalar perturbations through the tensor-to-scalar ratio r. We show that the expected level of systematic error in the Spider instrument is significantly below the amplitude of an interesting cosmological signal with r = 0.03. We present a scanning strategy that enables us to minimize uncertainty in the reconstruction of the Stokes parameters used to characterize the CMB, while accessing a relatively wide range of angular scales. Evaluating the amplitude of the polarized Galactic emission in the Spider field, we conclude that the polarized emission from interstellar dust is as bright or brighter than the cosmological signal at all Spider frequencies (90 GHz, 150 GHz, and 280 GHz), a situation similar to that found in the "Southern Hole." We show that two ∼ 20-day flights of the Spider instrument can constrain the amplitude of the B-mode signal to r < 0.03 (99% CL) even when foreground contamination is taken into account. In the absence of foregrounds, the same limit can be reached after one 20-day flight.

Inflation and String Theory

“…There are many experiments looking for B-modes on degree scales, including KeckArray [139], EBEX [140], SPIDER [141], ABS [142], and CLASS [143]); and on arcminute scales, including POLARBEAR [144], SPTpol [145], and ACTpol [146]). Finally, given the size of the signal seen by the BICEP2 collaboration, the Planck satellite has a chance to see the reionization peak in the B-mode spectrum at low .…”

“…In the limit c s 1, the amplitude of the entropy perturbations is boosted relative to the adiabatic fluctuations. The amplitude of the bispectrum can be suppressed, 141) where the angle Θ parameterizes how much of the final curvature perturbation arises from entropy perturbations, 44 with Θ = 0 if there is no transfer of entropy modes and Θ = π/2 if the final curvature perturbation is mostly of entropic origin. This can relax the constraint (5.135) on γ.…”

Status of Neutrino Properties and Future Prospects—Cosmological and Astrophysical Constraints

“…4/3 N eff (22) in the rhs of the Hubble equation (2), with N eff ≡ N eff − 3.046. Note that this substitution fully captures the effect of the additional species only if this is exactly massless, and not just very light (as in the case of a light massive sterile neutrino, for example-see section 10).…”

“…The Cosmology Large Angular Scale Surveyor (CLASS) [21] is working at mapping the CMB polarization field over 70% of the sky. The SPIDER balloon [22] successfully completed its first flight and is in preparation for the second launch likely at the end of 2018. In addition to CMB data, complementary information can be obtained by looking at the large-scale structure of the Universe.…”

On the emissivity of wire-grid polarizers for astronomical observations at mm-wavelengths

“…[1,2,3,4]), or as beamsplitters in Martin-Puplett interferometers (MPI, see [5]) . In fact, an array of metallic wires with diameter and spacing much smaller than the wavelength performs as an almost ideal polarizer at mm wavelengths (see e.g.…”