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Session 10 - AGN - Host Galaxies & Environment.
Display session, Monday, January 13
We present low-resolution absorption-line spectra of three candidate close ( < 3") companions to the low redshift QSOs 3C\,323.1, PG\,1700+518 and PKS\,2135-147. The spectra were obtained with LRIS on the Keck telescopes and with the Faint Object Spectrograph on the UH 2.2m telescope. For 3C\,323.1 and PG\,1700+518, we measure relative velocities that are consistent with an association between the QSOs and their companion galaxies. The spectral features of the companion galaxy to 3C\,323.1 indicate an older stellar population. In contrast, the spectrum of the companion galaxy to PG\,1700+518 shows strong Balmer absorption lines from a relatively young stellar population, along with the Mg\,Ib absorption feature and the 4000Å\ break from an older population. By modelling the two stellar components of this spectrum, it is possible to estimate the time that has elapsed since the end of the most recent major starburst event. This event may have coincided with an interaction that triggered the QSO activity. Finally, our spectroscopy shows conclusively that the supposed companion to PKS\,2135-147 is actually a projected Galactic G star.
Program listing for Monday