C.D.S. - SIMBAD4 rel 1.7 - 2021.03.06CET03:50:33

2012A&A...541A.126S - Astronomy and Astrophysics, volume 541A, 126-126 (2012/5-1)

Cosmic-ray-induced ionization in molecular clouds adjacent to supernova remnants. Tracing the hadronic origin of GeV gamma radiation.


Abstract (from CDS):

Energetic gamma rays (GeV to TeV photon energy) have been detected toward several supernova remnants (SNRs) that are associated with molecular clouds. If the gamma rays are produced mainly by hadronic processes rather than leptonic processes like bremsstrahlung, then the flux of energetic cosmic ray nuclei (>1GeV) required to produce the gamma rays can be inferred at the site where the particles are accelerated in SNR shocks. It is of great interest to understand the acceleration of the cosmic rays of lower energy (<1GeV) that accompany the energetic component. These particles of lower energy are most effective in ionizing interstellar gas, which leaves an observable imprint on the interstellar ion chemistry. A correlation of energetic gamma radiation with enhanced interstellar ionization can thus be used to support the hadronic origin of the gamma rays and to constrain the acceleration of ionizing cosmic rays in SNR. We propose a method to test the hadronic origin of GeV gamma rays from SNRs associated with a molecular cloud. We use observational gamma ray data for each SNR known to be associated with a molecular cloud, modeling the observations to obtain the underlying proton spectrum under the assumption that the gamma rays are produced by pion decay. Assuming that the acceleration mechanism does not only produce high energy protons, but also low energy protons, this proton spectrum at the source is then used to calculate the ionization rate of the molecular cloud. Ionized molecular hydrogen triggers a chemical network forming molecular ions. The relaxation of these ions results in characteristic line emission, which can be predicted. We show that the predicted ionization rate for at least two objects is more than an order of magnitude above Galactic average for molecular clouds, hinting at an enhanced formation rate of molecular ions. There will be interesting opportunities to measure crucial molecular ions in the infrared and submillimeter-wave parts of the spectrum.

Abstract Copyright:

Journal keyword(s): astroparticle physics - radiation mechanisms: non-thermal - ISM: clouds - cosmic rays - ISM: supernova remnants - gamma rays: ISM

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 IC 443 SNR 06 18 02.7 +22 39 36     10.11     ~ 1121 1
2 SNR G348.5+00.1 SNR 17 14 31.780 -38 28 34.50           ~ 200 3
3 SNR G349.7+00.2 SNR 17 18 10.160 -37 18 53.80           ~ 171 0
4 SNR G006.4-00.1 SNR 18 01 22.7 -23 17 20           ~ 664 1
5 W 30 SNR 18 05 38 -21 36.7           ~ 160 1
6 3C 391.0 Rad 18 49 23.3 -00 55 38           ~ 326 2
7 SNR G034.6-00.5 SNR 18 56 10.650 +01 13 21.30           ~ 846 2
8 W 49b SNR 19 11 09.000 +09 06 24.00           ~ 408 1
9 SNR G049.1-00.1 SNR 19 23 19.300 +14 09 21.00           ~ 245 0

    Equat.    Gal    SGal    Ecl

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