Search for the Optical Counterpart of the Vela Pulsar X‐Ray Nebula

Observations of the Vela pulsar region with the Chandra X-ray observatoryhave revealed the fine structure of its synchrotron pulsar-wind nebula (PWN),which showed an overall similarity with the Crab PWN. However, contrary to theCrab, no firm detection of the Vela PWN in optical has been reported yet. Tosearch for the optical counterpart of the X-ray PWN, we analyzed deep opticalobservations performed with different telescopes. We compared the opticalimages with those obtained with the Chandra ACIS to search for extendedemission patterns which could be identified as counterparts of the X-ray nebulaelements. Although some features are seen in the optical images, we find nocorrelation with the X-ray structure. Thus, we conclude that the diffuseoptical emission is more likely associated with filaments in the host Vela SNR.The derived upper limits on the optical flux from the PWN are compatibile,within the uncertainties, with the values expected on the basis of theextrapolations of the X-ray data.Comment: 19 pages, 6 figures. Accepted for publication in Ap