The Three-Dimensional Spatial Distribution of Interstellar Gas in the Milky Way: Implications for Cosmic Rays and High-Energy Gamma-Ray Emissions

Abstract

Direct measurements of cosmic ray (CR) species combined with observations of their associated gamma-ray emissions can be used to constrain models of CR propagation, trace the structure of the Galaxy, and search for signatures of new physics. The spatial density distribution of the interstellar gas is a vital element for all these studies. So far models have employed the 2D cylindrically symmetric geometry, but their accuracy is well behind that of the available data. In this paper, 3D spatial density models for the neutral and molecular hydrogen are constructed based on empirical model fitting to gas line-survey data. The developed density models incorporate spiral arms and account for the warping of the disk, and the increasing gas scale height with radial distance from the Galactic center. They are employed together with the GALPROP CR propagation code to investigate how the new 3D gas models affect calculations of CR propagation and high-energy gamma-ray intensity maps. The calculations made reveal non-trivial features that are directly related to the new gas models. The best-fit values for propagation model parameters employing 3D gas models are presented and they differ significantly from the values derived with the 2D gas density models that have been widely used. The combination of 3D CR and gas density models provide a more realistic basis for the interpretation of non-thermal emissions from the Galaxy.

Accepted for publication in ApJ

References in corpus (24)

• Parameterization of Gamma, e^+/- and Neutrino Spectra Produced by p-p Interaction in Astronomical Environment
• Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
• The Vertical Structure of the Outer Milky Way HI Disk
• Spatial distribution of interstellar gas in the innermost 3 kpc of our Galaxy
• The Spiral Structure of the Outer Milky Way in Hydrogen
• Dark matter in the Milky Way, II. the HI gas distribution as a tracer of the gravitational potential
• Measurement of boron and carbon fluxes in cosmic rays with the PAMELA experiment
• Solution of heliospheric propagation: unveiling the local interstellar spectra of cosmic ray species
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• High-Energy Gamma Rays from the Milky Way: Three-Dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities in the Interstellar Medium
• A Map of Dust Reddening to 4.5 kpc from Pan-STARRS1
• 3D Distribution of Molecular Gas in the Barred Milky Way
• Mapping Spiral Structure on the far side of the Milky Way
• A self-consistent model of Galactic stellar and dust infrared emission and the abundance of polycyclic aromatic hydrocarbons
• The incorrect rotation curve of the Milky Way
• Catalog of observed tangents to the spiral arms in the Milky Way galaxy
• Distribution and kinematics of atomic and molecular gas inside the Solar circle
• HelMod in the works: from direct observations to the local interstellar spectrum of cosmic-ray electrons
• Mapping the Extinction Curve in 3D: Structure on Kiloparsec Scales
• Optimization of Moment Masking for CO Spectral Line Surveys
• Constraining the pitch angle of the Galactic spiral arms in the Milky Way
• Kinetic Tomography I: A Method for Mapping the Milky Way's Interstellar Medium in Four Dimensions
• Reconciling the diffuse Galactic gamma-ray and the cosmic ray spectra
• Optical Thickness, Spin Temperature, and Correction Factor for Density of the Galactic HI Gas

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