Line profile of nuclear de-excitation gamma-ray emission from very hot plasma

Abstract

De-excitation gamma-ray lines, produced by nuclei colliding with protons, provide information about astrophysical environments where particles have kinetic energies of $10-100$ MeV per nucleon. In general, such environments can be categorized into two types: the interaction between non-thermal MeV cosmic rays and ambient gas, and the other is thermal plasma with a temperature above a few MeV. In this paper, we focus on the latter type and investigate the production of de-excitation gamma-ray lines in very hot thermal plasma, especially the dependence of the line profile on the plasma temperature. We have calculated the line profile of prompt gamma rays from ${}^{12}$C and ${}^{16}$O and found that when nuclei have a higher temperature than protons, gamma-ray line profiles can have a complex shape unique to each nucleus species. This is caused by anisotropic gamma-ray emission in the nucleus rest frame. We propose that the spectroscopy of nuclear de-excitation gamma-ray lines may enable to probe energy distribution in very hot astrophysical plasmas. This diagnostics can be a new and powerful technique to investigate the physical state of a two-temperature accretion flows onto a black hole, especially the energy distributions of the protons and nuclei, which are difficult to access for any other diagnostics.

arXiv comment12 pages, Accepted for publication in MNRAS

References in corpus (19)

• Advection-Dominated Accretion: A Self-Similar Solution
• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• Hot Accretion Flows Around Black Holes
• Advection-Dominated Accretion: Self-Similarity and Bipolar Outflows
• Thermal Equilibria of Accretion Disks
• Electron-Ion Temperature Equilibration in Collisionless Shocks: the Supernova Remnant-Solar Wind Connection
• Dual MeV Gamma-Ray and Dark Matter Observatory -- GRAMS Project
• High-Resolution Spectroscopy of Gamma-Ray Lines from the X-Class Solar Flare of 23 July, 2002
• On high-energy particles in accretion disk coronae of supermassive black holes: implications for MeV gamma rays and high-energy neutrinos from AGN cores
• Properties of the energetic particle distributions during the October 28, 2003 solar flare from INTEGRAL/SPI observations
• Electron-Ion Temperature Equilibration at Collisionless Shocks in Supernova Remnants
• Evidence for a neutral iron line generated by MeV protons from supernova remnants interacting with molecular clouds
• Gamma Ray Lines from the Orion Complex
• Shape of the 4.438 MeV gamma-ray line of ^12C from proton and alpha-particle induced reactions on ^12C and ^16O
• Nuclear de-excitation line spectrum of Cassiopeia A
• Nuclear de-excitation lines as a probe of low-energy cosmic rays
• New estimation of the nuclear de-excitation line emission from the supernova remnant Cassiopeia A
• Gamma-ray emission of hot astrophysical plasmas
• Nuclear $\gamma$-ray emission from very hot accretion flows