Determination of limits on disc masses around six pulsars at 15 and 90 μm

We have searched for evidence of emission at 15 mum with ISOCAM and at 90 mum with ISOPHOT from dust orbiting six nearby pulsars, both in binaries and in isolation, located at distances between about 100 to 1000 pc. No emission was detected at any of the pulsar positions, and for the nearest pulsar J0108-1431 the 3sigma upper limits on the flux density is about 66 mJy at 15 mum and 22.5 mJy at 90 mum. Upper limits on the masses of circumpulsar dust are inferred at a given temperature using a simple modelling of the radiated flux; they are compared to upper limits on orbiting mass obtained with the dust heating model of Foster & Fisher (1996). These results suggest that it is unlikely that any of these pulsars have sufficiently massive, circumpulsar discs, out of which planets may form in the future.