Precision constraints on radiative neutrino decay with CMB spectral distortion

Abstract

We investigate the radiative decay of the cosmic neutrino background, and its impact on the spectrum of the cosmic microwave background (CMB) that is known to be a nearly perfect black body. We derive exact formulae for the decay of a heavier neutrino into a lighter neutrino and a photon, ${\nu }_j\to {\nu }_i+\gamma$, and of absorption as its inverse, ${\nu }_i+\gamma \to {\nu }_j$, by accounting for the precise form of the neutrino momentum distribution. Our calculations show that if the neutrinos are heavier than $\mathcal{O}(0.1)$ eV, the exact formulae give results that differ by $\sim$50%, compared with approximate ones where neutrinos are assumed to be at rest. We also find that spectral distortion due to absorption is more important for heavy neutrino masses (by a factor of $\sim$10 going from a neutrino mass of 0.01 eV to 0.1 eV). By analyzing the CMB spectral data measured with COBE-FIRAS, we obtain lower limits on the neutrino lifetime of ${\tau }_{12}\gtrsim 4\times 10^{21}$ s (95% C.L.) for the smaller mass splitting and ${\tau }_{13}\sim {\tau }_{23}\gtrsim 10^{19}$ s for the larger mass splitting. These represent up to one order of magnitude improvement over previous CMB constraints. With future CMB experiments such as PIXIE, these limits will improve by roughly 4 orders of magnitude. This translates to a projected upper limit on the neutrino magnetic moment (for certain neutrino masses and decay modes) of ${\mu }_{\nu }<3\times 10^{-11}{\mu }_B$, where ${\mu }_B$ is the Bohr magneton. Such constraints would make future precision CMB measurements competitive with lab-based constraints on neutrino magnetic moments.

arXiv comment14 pages, 9 figures. v2: Added a number of references and clarifications. Matches version published in PRD

References in corpus (22)

• Planck 2015 results. XIII. Cosmological parameters
• The Cosmic Microwave Background Spectrum from the Full COBE/FIRAS Data Set
• Search for Majorana Neutrinos near the Inverted Mass Hierarchy Region with KamLAND-Zen
• The Primordial Inflation Explorer (PIXIE): A Nulling Polarimeter for Cosmic Microwave Background Observations
• How Magnetic is the Dirac Neutrino?
• Limiting neutrino magnetic moments with Borexino Phase-II solar neutrino data
• Neutrino mass in cosmology: status and prospects
• Reionization and cosmic microwave background distortions: a complete treatment of second order Compton scattering
• Model Independent Bounds on Magnetic Moments of Majorana Neutrinos
• Teasing bits of information out of the CMB energy spectrum
• The Power Spectrum of the Sunyaev-Zel'dovich Effect
• Neutrino Mass Hierarchy
• Distinguishing different scenarios of early energy release with spectral distortions of the cosmic microwave background
• Prospects for Measuring Cosmic Microwave Background Spectral Distortions in the Presence of Foregrounds
• Neutrino oscillations: the rise of the PMNS paradigm
• Sunyaev-Zeldovich Fluctuations from the First Stars?
• From transition magnetic moments to majorana neutrino masses
• Revisiting cosmological bounds on radiative neutrino lifetime
• CP Violation in the Lepton Sector and Implications for Leptogenesis
• Revisiting Large Neutrino Magnetic Moments
• Photon Spectrum Produced by the Late Decay of a Cosmic Neutrino Background
• Triangle Inequalities for Majorana-Neutrino Magnetic Moments

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• Cosmological Constraints on Invisible Neutrino Decays Revisited
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• Invisible neutrino decay in precision cosmology
• Determining the Neutrino Lifetime from Cosmology
• Probing the Blue Axion with Cosmic Optical Background Anisotropies
• Discovering leptonic forces using non-conserved currents
• Probing relic neutrino decays with 21 cm cosmology
• Microwave Spectro-Polarimetry of Matter and Radiation across Space and Time
• Constraining Neutrino Lifetimes and Magnetic Moments via Solar Neutrinos in the Large Xenon Detectors
• Detecting the radiative decay of the cosmic neutrino background with line-intensity mapping
• Invisible Neutrino Decays as Origin of TeV Gamma Rays from GRB221009A
• Unstable Cosmic Neutrino Capture
• New Horizons in Cosmology with Spectral Distortions of the Cosmic Microwave Background
• Impostor Among $\nu$s: Dark Radiation Masquerading as Self-Interacting Neutrinos
• Neutrino decays as a natural explanation of the neutrino mass tension
• High Energy Physics and Cosmology at the Unification Frontier: Opportunities and Challenges in the coming years
• Sensitivities of KM3NeT on decaying dark matter
• Helicity-changing Decays of Cosmological Relic Neutrinos
• Improved cosmological constraints on the neutrino mass and lifetime
• Probing 21cm cosmology and radiative neutrino decays