Planck intermediate results - XXXI. Microwave survey of Galactic supernova remnants

Author(s): Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, AJ; Barreiro, RB; Battaner, E; Benabed, K; Benoit-Levy, A; Bernard, JP; Bersanelli, M; Bielewicz, P; Bobin, J; Bond, JR; Borrill, J; Bouchet, FR; Brogan, CL; Burigana, C; Cardoso, JF; Catalano, A; Chamballu, A; Chiang, HC; Christensen, PR; Colombi, S; Colombo, LPL; Crill, BP; Curto, A; Cuttaia, F; Davies, RD; Davis, RJ; De Bernardis, P; De Rosa, A; De Zotti, G; Delabrouille, J; Desert, FX; Dickinson, C; Diego, JM; Donzelli, S; Dore, O; Dupac, X; Enslin, TA; Eriksen, HK; Finelli, F; Forni, O; Frailis, M; Fraisse, AA; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giraud-Heraud, Y; Gonzalez-Nuevo, J; Gorski, KM; Gregorio, A; Gruppuso, A; Hansen, FK; Harrison, DL; Hernandez-Monteagudo, C; Herranz, D; Hildebrandt, SR | Abstract: © ESO, 2016. The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 16 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the mechanism for microwave emission. In only one case, IC 443, is there high-frequency emission clearly from dust associated with the supernova remnant. In all cases, the low-frequency emission is from synchrotron radiation. As predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, a single power law is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, Sν ∝ ν-α, with the spectral index, α, increasing by 0.5-1 above a break frequency in the range 10-60 GHz. The break could be due to synchrotron losses.