[en] In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849"+/-0.001" with a magnitude difference of 2.14+/-0.03 in V and I. We see no trace of a lensing galaxy. From the FOS observations, we find that J03.13 A and B have identical spectra within the measurement uncertainties. The data also show that spectroscopic contamination of B by A is negligible. We do confirm the redshift z=2.545 for J03.13 A and B (emission-lines due to Ly-beta lambda1025 and O VI lambdalambda1031, 1037 are also detected), first derived from an unresolved ground-based spectrum of the two components by Claeskens et al. We also find that the absorption line system at z=2.344 (CIV and Ly-alpha) is present in the spectra of A and B. On the contrary, the absorption line system at z=1.085 (MgII) is only present in the spectrum of J03.13 A. If this latter system is associated with the lens, we may expect that image A consists of two radially merging images with a very small angular separation. From the WFPC2 imagery, we can rule out the presence of a third component fainter than A by up to 5.2mag. with an angular separation >=0.13".
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Surdej, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Claeskens J.-F., Surdej, J., Remy, M., 1996 A&A 305, L9
Holtzman J.A. et al., 1995, PASP 107, 1065
Hook R., Lucy L., 1994, in "The restoration of HST images and spectra - II", R. Hanisch & R. White (eds.), p. 86
Krist J., 1997, "WFPC2 ghosts, scatter and PSF field dependence", postcript document available at the URL: http://www.stsci.edu/-ftp/instrument_news/WFPC2/Wfpc2_serv/wfpc2_ghosts.ps
Maza J., Ruiz M.T., Gonzalez L.E., Wischnjewsky M., Anteza, R., 1993, Rev. Mex. Astron. Astrof. 25, 51
Østensen R., Remy M., Lindblad P.O., Refsdal S., Stabell R. et al., 1997, A&AS, in press
Surdej J., Claeskens J.-F., Crampton D., Filippenko A. V., Hutsemékers D. et al., 1993, AJ 105, 2064
Whitmore, B., 1997, "Photometry with the WFPC2", postcript document available at the URL: http://www.stsci.edu/ftp/-instrument_news/WFPC2/Wfpc2_phot/photom2.ps