We report measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 \mu m with the Spitzer Infrared Array Camera ( IRAC ) .
Our measured occultation depths are 0.510 \pm 0.042 % and 0.41 \pm 0.11 % at 4.5 and 8 \mu m , respectively .
In addition to the CoRoT optical measurements , these planet/star flux ratios indicate a poor heat distribution to the night side of the planet and are in better agreement with an atmosphere free of temperature inversion layer .
Still , the presence of such an inversion is not definitely ruled out by the observations and a larger wavelength coverage is required to remove the current ambiguity .
Our global analysis of CoRoT , Spitzer and ground-based data confirms the large mass and size of the planet with slightly revised values ( M _ { p } = 3.47 \pm 0.22 Â M _ { J } , R _ { p } = 1.466 \pm 0.044 Â R _ { J } ) .
We find a small but significant offset in the timing of the occultation when compared to a purely circular orbital solution , leading to e \cos { \omega } = -0.00291 \pm 0.00063 where e is the orbital eccentricity and \omega is the argument of periastron .
Constraining the age of the system to be at most of a few hundreds of Myr and assuming that the non-zero orbital eccentricity is not due to a third undetected body , we model the coupled orbital-tidal evolution of the system with various tidal Q values , core sizes and initial orbital parameters .
For Q _ { s } ^ { \prime } = 10 ^ { 5 } -10 ^ { 6 } , our modelling is able to explain the large radius of CoRoT-2b if Q _ { p } ^ { \prime } \leq 10 ^ { 5.5 } through a transient tidal circularization and corresponding planet tidal heating event .
Under this model , the planet will reach its Roche limit within 20 Myr at most .