Probing cosmic-ray acceleration and propagation with H                         3                         +                          observations

Nick Indriolo; Brian D. Fields; Benjamin J. McCall

doi:10.1063/1.4906696

Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations

Nick Indriolo, Brian D. Fields, Benjamin J. McCall

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

As cosmic rays traverse the interstellar medium (ISM) they interact with the ambient gas in various ways. These include ionization of atoms and molecules, spallation of nuclei, excitation of nuclear states, and production of pions among others. All of these interactions produce potential observables which may be used to trace the flux of cosmic rays. One such observable is the molecular ion H ₃ ⁺ -produced via the ionization of an H ₂ molecule and its subsequent collision with another H ₂ -which can be identified by absorption lines in the 3.5-4 μm spectral region. We have detected H ₃ ⁺ in several Galactic diffuse cloud sight lines and used the derived column densities to infer ζ ₂ , the cosmic-ray ionization rate of H ₂ . Ionization rates determined in this way vary from about 7×10 ^-17 s ^-1 to about 8×10 ^-16 s ^-1 , and suggest the possibility of discrete sources producing high local fluxes of low-energy cosmic rays. Theoretical calculations of the ionization rate from postulated cosmic-ray spectra also support this possibility. Our recent observations of H ₃ ⁺ near the supernova remnant IC 443 (a likely site of cosmic-ray acceleration) point to even higher ionization rates, on the order of 10 ^-15 s ^-1 . Together, all of these results can further our understanding of the cosmic-ray spectrum both near the acceleration source and in the general Galactic ISM.

Original language	English (US)
Title of host publication	Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010
Editors	Theodore E. Simos, Theodore E. Simos, George Maroulis, Theodore E. Simos, Theodore E. Simos
Publisher	American Institute of Physics Inc.
Pages	370-372
Number of pages	3
ISBN (Electronic)	9780735412828
DOIs	https://doi.org/10.1063/1.4906696
State	Published - 2015
Event	International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010 - Psalidi, Kos, Greece Duration: Oct 3 2010 → Oct 8 2010

Publication series

Name	AIP Conference Proceedings
Volume	1642
ISSN (Print)	0094-243X
ISSN (Electronic)	1551-7616

Conference

Conference	International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010
Country/Territory	Greece
City	Psalidi, Kos
Period	10/3/10 → 10/8/10

Keywords

Cosmic Rays
Interstellar Medium
Supernova Remnants

ASJC Scopus subject areas

General Physics and Astronomy

Online availability

10.1063/1.4906696

Library availability

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Cite this

Indriolo, N., Fields, B. D., & McCall, B. J. (2015). Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations In T. E. Simos, T. E. Simos, G. Maroulis, T. E. Simos, & T. E. Simos (Eds.), Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010 (pp. 370-372). Article 4906696 (AIP Conference Proceedings; Vol. 1642). American Institute of Physics Inc.. https://doi.org/10.1063/1.4906696

Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations . / Indriolo, Nick; Fields, Brian D.; McCall, Benjamin J.
Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010. ed. / Theodore E. Simos; Theodore E. Simos; George Maroulis; Theodore E. Simos; Theodore E. Simos. American Institute of Physics Inc., 2015. p. 370-372 4906696 (AIP Conference Proceedings; Vol. 1642).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Indriolo, N, Fields, BD & McCall, BJ 2015, Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations in TE Simos, TE Simos, G Maroulis, TE Simos & TE Simos (eds), Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010., 4906696, AIP Conference Proceedings, vol. 1642, American Institute of Physics Inc., pp. 370-372, International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010, Psalidi, Kos, Greece, 10/3/10. https://doi.org/10.1063/1.4906696

Indriolo N, Fields BD, McCall BJ. Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations In Simos TE, Simos TE, Maroulis G, Simos TE, Simos TE, editors, Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010. American Institute of Physics Inc. 2015. p. 370-372. 4906696. (AIP Conference Proceedings). doi: 10.1063/1.4906696

Indriolo, Nick ; Fields, Brian D. ; McCall, Benjamin J. / Probing cosmic-ray acceleration and propagation with H ₃ ⁺ observations Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010, ICCMSE 2010. editor / Theodore E. Simos ; Theodore E. Simos ; George Maroulis ; Theodore E. Simos ; Theodore E. Simos. American Institute of Physics Inc., 2015. pp. 370-372 (AIP Conference Proceedings).

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abstract = " As cosmic rays traverse the interstellar medium (ISM) they interact with the ambient gas in various ways. These include ionization of atoms and molecules, spallation of nuclei, excitation of nuclear states, and production of pions among others. All of these interactions produce potential observables which may be used to trace the flux of cosmic rays. One such observable is the molecular ion H 3 + -produced via the ionization of an H 2 molecule and its subsequent collision with another H 2 -which can be identified by absorption lines in the 3.5-4 μm spectral region. We have detected H 3 + in several Galactic diffuse cloud sight lines and used the derived column densities to infer ζ 2 , the cosmic-ray ionization rate of H 2 . Ionization rates determined in this way vary from about 7×10 -17 s -1 to about 8×10 -16 s -1 , and suggest the possibility of discrete sources producing high local fluxes of low-energy cosmic rays. Theoretical calculations of the ionization rate from postulated cosmic-ray spectra also support this possibility. Our recent observations of H 3 + near the supernova remnant IC 443 (a likely site of cosmic-ray acceleration) point to even higher ionization rates, on the order of 10 -15 s -1 . Together, all of these results can further our understanding of the cosmic-ray spectrum both near the acceleration source and in the general Galactic ISM.",

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author = "Nick Indriolo and Fields, {Brian D.} and McCall, {Benjamin J.}",

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AB - As cosmic rays traverse the interstellar medium (ISM) they interact with the ambient gas in various ways. These include ionization of atoms and molecules, spallation of nuclei, excitation of nuclear states, and production of pions among others. All of these interactions produce potential observables which may be used to trace the flux of cosmic rays. One such observable is the molecular ion H 3 + -produced via the ionization of an H 2 molecule and its subsequent collision with another H 2 -which can be identified by absorption lines in the 3.5-4 μm spectral region. We have detected H 3 + in several Galactic diffuse cloud sight lines and used the derived column densities to infer ζ 2 , the cosmic-ray ionization rate of H 2 . Ionization rates determined in this way vary from about 7×10 -17 s -1 to about 8×10 -16 s -1 , and suggest the possibility of discrete sources producing high local fluxes of low-energy cosmic rays. Theoretical calculations of the ionization rate from postulated cosmic-ray spectra also support this possibility. Our recent observations of H 3 + near the supernova remnant IC 443 (a likely site of cosmic-ray acceleration) point to even higher ionization rates, on the order of 10 -15 s -1 . Together, all of these results can further our understanding of the cosmic-ray spectrum both near the acceleration source and in the general Galactic ISM.

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