Publication Date:
2016-07-29
Description:
We report the analysis of the first deep optical observations of three isolated -ray pulsars detected by the Fermi Gamma-ray Space Telescope : the radio-loud PSR J0248+6021 and PSR J0631+1036, and the radio-quiet PSR J0633+0632. The latter has also been detected in the X-rays. The pulsars are very similar in their spin-down age ( ~ 40–60 kyr), spin-down energy ( $\dot{E} \sim 10^{35}$ erg s –1 ), and dipolar surface magnetic field ( B ~ 3–5 x 10 12 G). These pulsars are promising targets for multiwavelength observations, since they have been already detected in -rays and in radio or X-rays. None of them has been detected yet in the optical band. We observed the three pulsar fields in 2014 with the Spanish 10.4 m Gran Telescopio Canarias (GTC). We could not find any candidate optical counterpart to the three pulsars close to their most recent radio or Chandra positions down to 3 limits of g ' ~ 27.3, g ' ~ 27, g ' ~ 27.3 for PSR J0248+6021, J0631+1036, and J0633+0632, respectively. From the inferred optical upper limits and estimated distance and interstellar extinction, we derived limits on the pulsar optical luminosity. We also searched for the X-ray counterpart to PSR J0248+6021 with Chandra but we did not detect the pulsar down to a 3 flux limit of 5 x 10 –14 erg cm –2 s –1 (0.3–10 keV). For all these pulsars, we compared the optical flux upper limits with the extrapolations in the optical domain of the -ray spectra and compared their multiwavelength properties with those of other -ray pulsars of comparable age.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
