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Evidence for a wide electron spectra scatter among different SNR regions from high radio-frequency observations

Published online by Cambridge University Press:  17 October 2017

A. Pellizzoni ,
E. Egron ,
M. N. Iacolina ,
S. Loru ,
M. Marongiu ,
S. Righini ,
M. Cardillo ,
A. Giuliani ,
S. Mulas  and
G. Murtas
...Show all authors
A. Pellizzoni
Affiliation:
INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy email: [email protected]
E. Egron
Affiliation:
INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy email: [email protected]
M. N. Iacolina
Affiliation:
INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy email: [email protected]
S. Loru
Affiliation:
INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy email: [email protected] Dip. di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, 09042 Monserrato, Italy
M. Marongiu
Affiliation:
INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy email: [email protected]
S. Righini
Affiliation:
INAF, Istituto di Radio Astronomia di Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
M. Cardillo
Affiliation:
INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
A. Giuliani
Affiliation:
INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Milano, via E. Bassini 15, 20133 Milano, Italy
S. Mulas
Affiliation:
Dip. di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, 09042 Monserrato, Italy
G. Murtas
Affiliation:
Dip. di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, 09042 Monserrato, Italy
D. Simeone
Affiliation:
Dip. di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, 09042 Monserrato, Italy
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Abstract

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In the framework of the Sardinia Radio Telescope (SRT) Early Science Program, we obtained single-dish high-resolution imaging of the Supernova Remnants IC443 and W44 at 7 GHz. By coupling them with SRT 1.5 GHz maps, we provided spatially-resolved spectral measurements that are highlighting a spread in spectral slope distribution. The observed features range from flat or slightly inverted spectra corresponding to bright radio limbs and filaments, to relatively steep spectra in fainter radio regions. Different theoretical possibilities explaining the above challenging findings are discussed. In particular, we exclude that the observed region-dependent wide spread in spectral slope distribution could be related to absorption processes. Our high-frequency results can be directly related to distinct electron populations in the SNRs including secondary hadronic electrons and resulting from different shocks conditions and/or undergoing different cooling processes. Integrated fluxes associated with the whole SNRs obtained by SRT in comparison with previous results in the literature support the evidence for a slight spectral steepening above 1 GHz for both sources, which could be related to primary electrons or more likely secondary hadronic electrons cut-offs.

Keywords

ISM: supernova remnantsISM: individual objects: W44, IC443radio continuum: ISM
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S331: Supernova 1987A:30 years later - Cosmic Rays and Nuclei from Supernovae and their aftermaths , February 2017 , pp. 194 - 200
Copyright
Copyright © International Astronomical Union 2017 

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