* Astronomy

Title: SDSS J094533.99+100950.1 - the Rosetta stone for weak emission line quasars?
Authors: Krzysztof Hryniewicz (1), Bozena Czerny (2), Marek Nikolajuk (1), Joanna Kuraszkiewicz (3) ((1) Faculty of Physics, Univ. of Bialystok, Poland,(2) N.Copernicus Astronomical Center, Poland, (3) Harvard-Smithsonian CfA, USA)

Weak emission line quasars is a rare and puzzling group of objects. In this paper we present one more object of this class found in the Sloan Digital Sky Survey (SDSS). The quasar has practically no C IV emission line, a red continuum very similar to the steepest of the quasar composite spectra of Richards et al., is not strongly affected by absorption and the Mg II line is strong enough to measure the black hole mass. The Eddington ratio in this object is about 0.25, and the line properties are not consistent with the trends expected at high accretion rates. We propose that the most probable explanation of the line properties in this object, and perhaps in all weak emission line quasars, is that the quasar activity has just started. The disk wind is freshly launched so the low ionisation lines which form close to the disk surface are already observed but the wind did not reach yet the regions where high ionisation lines or narrow line components form. The relatively high frequency of such a phenomenon might additionally indicate that the quasar active phase consists of several sub-phases, each starting with fresh build-up of Broad Line Region.

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