Spectroscopy of Close Companions to QSOs and the Ages of Interaction-Induced Starbursts

摘要: We present low-resolution absorption-line spectra of three candidate close ( < 3 arcsec) companions to the low redshift QSOs 3CR 323.1, PG 1700+518, and PKS 2135-147. The were obtained with LRIS on Keck telescopes Faint Object Spectrograph University Hawaii 2.2 m telescope. For 323.1 we measure relative velocities that are consistent an association between their companion galaxies. spectral features galaxy indicate a stellar population intermediate age (approx. 2.3 Gyr). In contrast, spectrum object 1700+518 shows strong Balmer absorption lines from relatively young population, along Mg Ib feature 4000 A break older population. By modeling two components this spectrum, it is possible estimate time has elapsed since end most recent major starburst event: obtain approx. 0.1 Gyr. This event may have coincided interaction triggered QSO activity. Finally, our spectroscopy conclusively supposed 2135-147 actually projected Galactic G star.