Recurrence of the Blue Wing Enhancements in the High-Ionization Lines of SDSS 1004+4112A

Gómez-Álvarez, P.; Mediavilla, E.; Muñoz, J. A.;Arribas, S.; Sánchez, S. F.; Oscoz, A.; Prada, F.; Serra-Ricart, M.. Recurrence of the Blue Wing Enhancements in the High-Ionization Lines of SDSS 1004+4112A. The Astrophysical Journal. 2006, Vol. Volume 645, Issue 1, pp. L5-L8, p. -2006.

We present integral field spectroscopic observations of the quadruple-lensed QSO SDSS 1004+4112 taken with the fiber system INTEGRAL at the William Herschel Telescope on 2004 January 19. In 2003 May, a blueward enhancement in the high-ionization lines of SDSS 1004+4112A was detected, and then it faded. Our observations are the first to note a second event of similar characteristics less than 1 year after. Although initially attributed to microlensing, the resemblance among the spectra of both events and the absence of microlensing-induced changes in the continuum of component A are puzzling. The lack of a convincing explanation under the microlensing or intrinsic variability hypotheses makes the observed enhancements particularly relevant, calling for close monitoring of this object.