5 Non-detected pulsars

  

Table 4: List of the pulsars with no WENSS counterpart, their expected flux densities at 325 MHz and the local noise in the WENSS map. The expected flux density for pulsars B0841+80, J1012+5307 and B1639+36A is equal to their 400 MHz flux density. The flux density of PSR J2044+46 is not known. "ND'' in the last column indicates, that the expected pulsar flux density is higher than three times the local noise level

$$\begin{tabular}{lr@{\mbox{}}l@{ $\pm$ }r@{\mbox{}}lrr} \hline... ...351+61 & 23& & 4& & 5.5 & ND \\ \\ \hline\hline \end{tabular}$$

Table 4 lists the pulsars that have no counterpart in the WENSS. In 14 cases the expected pulsar flux density is higher than three times the local noise level. Still, the pulsar was not detected. In two cases no reliable pulsar flux density estimate at 325 MHz is available. In three other cases the estimate is based on 400 MHz observations. In case of PSRs B0841+80 and B1839+36A this was done, because there was no spectral information available. The spectrum of PSR J1012+5307 might also have a low frequency turnover (see its spectrum as plotted by Kramer et al. 1999). Its flux density is known to vary by up to a factor four from its mean value of 30 mJy (Nicastro et al. 1995).

Five (and possibly eight) pulsars are detected, which were expected to be not detectable. The number of non-detected sources that were expected to have a flux density greater than the detection limit, should be roughly the same as the number of unexpected detections. The difference may be due to Poisson fluctuations in the (small) number of pulsars in this study.

  

Table 5: List of spectral indices from Lorimer et al. (1995) and from a WENSS-NVSS flux density comparison for all pulsars with both a WENSS and a NVSS counterpart. The spectral index for PSR J1518+4904 was taken from Kramer et al. (1999). The errors on the pulsar spectral index (second column) include variations due to scintillation, the errors on the WENSS-NVSS spectral index do not include scintillation effects

$$\begin{tabular}{ll@{ $\pm$ }ll@{ $\pm$ }l} \hline\hline \mult... ...$-$1.5 & 0.2 & $-$1.44 & 0.06\\ \\ \hline\hline \end{tabular}$$