2016/05/31 by Xingang Chen, P. Daniel Meerburg, Moritz Münchmeyer
Earth and Planetary Sciences · Physics and Astronomy · #Amplitude #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic background radiation #Cosmic microwave background #Cosmic variance #Cosmology #Dark matter #Galaxy #Inflation (cosmology) #Physics #Planck #Precipitation Measurement and Analysis #Primordial fluctuations #Quantum mechanics #Radio Astronomy Observations and Technology #Redshift #Spectral density #Statistics #Theoretical physics #Universe #astro-ph.CO #hep-th
paper · pdf · doi:10.1088/1475-7516/2016/09/023
Matches version accepted for publication. Changes made to forecasting; using k space instead of \ell space. Forecasted constraints significantly improved for some features
arxiv created 2016/08/17 · openalex publication_date 2016/09/19 · arxiv updated 2016/09/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Detecting a deviation from a featureless primordial power spectrum of fluctuations would give profound insight into the physics of the primordial Universe. Depending on their nature, primordial features can either provide direct evidence for the inflation scenario or pin down details of the inflation model. Thus far, using the cosmic microwave background (CMB) we have only been able to put stringent constraints on the amplitude of features, but no significant evidence has been found for such signals. Here we explore the limit of the experimental reach in constraining such features using 21 cm tomography at high redshift. A measurement of the 21 cm power spectrum from the Dark Ages is generally considered as the ideal experiment for early Universe physics, with potentially access to a large number of modes. We consider three different categories of theoretically motivated models: the sharp feature models, resonance models, and standard clock models. We study the improvements on bounds on features as a function of the total number of observed modes and identify parameter degeneracies. The detectability depends critically on the amplitude, frequency and scale-location of the features, as well as the angular and redshift resolution of the experiment. We quantify these effects by considering different fiducial models. Our forecast shows that a cosmic variance limited 21 cm experiment measuring fluctuations in the redshift range 30 ⩽ z ⩽ 100 with a 0.01-MHz bandwidth and sub-arcminute angular resolution could potentially improve bounds by several orders of magnitude for most features compared to current Planck bounds. At the same time, 21 cm tomography also opens up a unique window into features that are located on very small scales.