A Constraint on Primordial B-modes from the First Flight of the Spider Balloon-borne Telescope

Abstract

We present the first linear polarization measurements from the 2015 long-duration balloon flight of Spider, which is an experiment that is designed to map the polarization of the cosmic microwave background (CMB) on degree angular scales. The results from these measurements include maps and angular power spectra from observations of 4.8% of the sky at 95 and 150 GHz, along with the results of internal consistency tests on these data. While the polarized CMB anisotropy from primordial density perturbations is the dominant signal in this region of sky, Galactic dust emission is also detected with high significance. Galactic synchrotron emission is found to be negligible in the Spider bands. We employ two independent foreground-removal techniques to explore the sensitivity of the cosmological result to the assumptions made by each. The primary method uses a dust template derived from Planck data to subtract the Galactic dust signal. A second approach, which constitutes a joint analysis of Spider and Planck data in the harmonic domain, assumes a modified-blackbody model for the spectral energy distribution of the dust with no constraint on its spatial morphology. Using a likelihood that jointly samples the template amplitude and r parameter space, we derive 95% upper limits on the primordial tensor-to-scalar ratio from Feldman–Cousins and Bayesian constructions, finding r < 0.11 and r < 0.19, respectively. Roughly half the uncertainty in r derives from noise associated with the template subtraction. New data at 280 GHz from Spider’s second flight will complement the Planck polarization maps, providing powerful measurements of the polarized Galactic dust emission.

Improved Constraints on Cosmic Birefringence from the WMAP and Planck Cosmic Microwave Background Polarization Data

“…To this end, both on-going and future groundbased [58][59][60][61][62][63][64][65][66], balloon-borne [67,68], and spaceborne [69,70] experiments are expected to lead to a convincing discovery (or otherwise) of cosmic birefringence. If proven to be a cosmological signal, isotropic cosmic birefringence would have a profound impact on cosmology, particle physics, and quantum gravity [71][72][73][74][75][76][77][78][79][80][81].…”

New physics from the polarised light of the cosmic microwave background

“…Sensitivity of polarisation to new physics that violates parity symmetry offers exciting opportunities for discovery, which may tell us the fundamental physics behind dark matter, dark energy, and cosmic inflation. The science topics described in this article may shed new light on the way polarisation data from on-going [16][17][18][19][20][21][22]282 and future CMB experiments [23][24][25][26] are obtained, calibrated, and analysed.…”

“…The scalar mode explains the observed properties of cosmic structures 1,6 . The tensor mode is yet to be discovered 21,22,66,159 .…”

“…Polarised light of the CMB may help answer these questions. Their importance is widely recognised, and there are beautiful measurements of CMB polarisation from two space missions, the National Aeronautics and Space Administration (NASA) Wilkinson Microwave Anisotropy Probe (WMAP) 14 and the European Space Agency (ESA) Planck 15 , as well as from a host of ground-based [16][17][18][19][20][21] and balloon-borne 22 experiments. The rate at which the sensitivity of CMB experiments has improved over the last 2 decades is staggering: the noise level has dropped by 3 orders of magnitude, nearly exponen-tially with time.…”

Snowmass2021 Theory Frontier White Paper: Data-Driven Cosmology

“…In the context of inflation, a detection of primordial B modes would provide evidence for quantum fluctuations in the spacetime metric itself, would imply that inflation took place at energy scales comparable to those associated with grand unified theories, and would imply a Planckian field range, just to mention some of the consequences. Because of these far-reaching implications, several CMB experiments are currently searching for this polarization pattern [16][17][18][19][20][21] and more will begin taking data soon.…”