Comparing
samples of SNR
ß radio-identified SNR: dense HII regions
core-collapse SNe (young
population)
ß optically-identified SNR: low-density regions
mostly Type Ia (old population)
ß X-ray SNR: both, but brighter when associated to radio SNR
Radio + X-ray (+ optical)
X-ray + optical
1036 erg/s
L
Core-collapse
Type Ia