Probing local cosmic rays using Fermi-LAT observation of a mid-latitude region in the third Galactic quadrant

Abstract

The $\gamma$-ray observation of interstellar gas provides a unique way to probe the cosmic rays (CRs) outside the solar system. In this work, we use an updated version of Fermi-LAT data and recent multi-wavelength tracers of interstellar gas to re-analyze a mid-latitude region in the third Galactic quadrant and estimate the local CR proton spectrum. Two $\gamma$-ray production cross section models for $pp$ interaction, the commonly used one from Kamae et al. (2006) and the up-to-date one from Kafexhiu et al. (2014), are adopted separately in the analysis. Both of them can well fit the emissivity and the derived proton spectra roughly resemble the direct measurements from AMS-02 and Voyager 1, but rather different spectral parameters are indicated. A break at $4\pm 1\mathrm{GeV}{c}^{-1}$ is shown if the cross section model by Kamae et al. (2006) is adopted. The resulting spectrum is $\lesssim 20\%$ larger than the AMS-02 observation above $15\mathrm{GeV}$ and consistent with the de-modulated spectrum within $2\%$. The proton spectrum based on the cross section model of Kafexhiu et al. (2014) is about $1.4-1.8$ times that of AMS-02 at $2-100\mathrm{GeV}$, however the difference decreases to $20\%$ below $10\mathrm{GeV}$ with respect to the de-modulated spectrum. A spectral break at $20\pm 11\mathrm{GeV}{c}^{-1}$ is required in this model. An extrapolation down to $300\mathrm{MeV}$ is performed to compare with the observation of Voyager 1, and we find a deviation of $\lesssim 2.5\sigma$ for both the models. In general, an approximately consistent CR spectrum can be obtained using $\gamma$-ray observation nowadays, but we still need a better $\gamma$-ray production cross section model to derive the parameters accurately.

arXiv comment10 pages, 6 figures. Accepted for publication in PRD

References in corpus (56)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The SIMBAD astronomical database
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Propagation of cosmic-ray nucleons in the Galaxy
• The Interstellar Environment of our Galaxy
• Planck 2013 results. XI. All-sky model of thermal dust emission
• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Fermi-LAT Observations of the Diffuse Gamma-Ray Emission: Implications for Cosmic Rays and the Interstellar Medium
• Diffuse continuum gamma rays from the Galaxy
• The Fermi Large Area Telescope On Orbit: Event Classification, Instrument Response Functions, and Calibration
• Planck Early Results: All sky temperature and dust optical depth from Planck and IRAS: Constraints on the "dark gas" in our galaxy
• Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
• Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies
• Parameterization of Gamma, e^+/- and Neutrino Spectra Produced by p-p Interaction in Astronomical Environment
• The Spectrum and Morphology of the Fermi Bubbles
• The Vertical Structure of Warm Ionised Gas in the Milky Way
• Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
• Planck 2013 results. XIII. Galactic CO emission
• Fermi observations of Cassiopeia and Cepheus: diffuse gamma-ray emission in the outer Galaxy
• Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes
• The On-orbit Calibrations for the Fermi Large Area Telescope
• Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations
• A New Model For The Loop-I (The North Polar Spur) Region
• Radial distribution of the diffuse gamma-ray emissivity in the galactic disk
• Constraints on the Cosmic-Ray Density Gradient beyond the Solar Circle from Fermi gamma-ray Observations of the Third Galactic Quadrant
• Fermi LAT Observation of Diffuse Gamma-Rays Produced Through Interactions between Local Interstellar Matter and High Energy Cosmic Rays
• Planck 2015 results. XXV. Diffuse low-frequency Galactic foregrounds
• Imprints of Cosmic Rays in Multifrequency Observations of the Interstellar Emission
• Fermi-LAT improved Pass~8 event selection
• A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey
• Low-energy break in the spectrum of Galactic cosmic rays
• Cosmic rays, gas and dust in nearby anticentre clouds : I -- CO-to-H2 conversion factors and dust opacities
• Fermi LAT study of cosmic-rays and the interstellar medium in nearby molecular clouds
• Planck intermediate results. XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies
• Probing Cosmic Rays in Nearby Giant Molecular Clouds with the Fermi Large Area Telescope
• The cosmic-ray and gas content of the Cygnus region as measured in gamma rays by the Fermi Large Area Telescope
• Molecular Clouds as Cosmic-Ray Barometers
• Cosmic ray spectrum in the local Galaxy
• Gamma Rays from Molecular Clouds
• Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope
• Fermi-LAT Observations of High- and Intermediate-Velocity Clouds: Tracing Cosmic Rays in the Halo of the Milky Way
• Optically thick HI does not dominate dark gas in the local ISM
• Planck intermediate results. XXVIII. Interstellar gas and dust in the Chamaeleon clouds as seen by Fermi LAT and Planck
• Fermi-LAT observations of the Sagittarius B complex
• Studies on cosmic ray nuclei with Voyager, ACE and AMS-02: I. local interstellar spectra and solar modulation
• Cosmic-rays, gas, and dust in nearby anticentre clouds : II -- Interstellar phase transitions and the Dark Neutral Medium
• Cosmic-rays, gas, and dust in nearby anti-centre clouds : III -- Dust extinction, emission, and grain properties
• Quantifying the Interstellar Medium and Cosmic Rays in the MBM 53, 54, and 55 Molecular Clouds and the Pegasus Loop using Fermi-LAT Gamma-ray Observations
• Comparative study of gamma-ray emission from molecular clouds and star-forming galaxies
• Calibrating Column Density Tracers with Gamma-ray Observations of the $\rho$ Ophiuchi Molecular Cloud
• High Latitude, Translucent Molecular Clouds as Probes of Local Cosmic Rays
• Detection of the Characteristic Pion-Decay Signature in the Molecular Clouds

Cited by in corpus (3)

• Study of the Cosmic Rays and Interstellar Medium in Local HI Clouds using Fermi-LAT Gamma-Ray Observations
• Galactic Gamma Ray Background from Interactions of Cosmic Rays
• A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone