Origins and Properties of QSO-intrinsic Narrow Absorption Lines and their Host QSOs

Open Access
Ganguly, Rajib
Graduate Program:
Astronomy and Astrophysics
Doctor of Philosophy
Document Type:
Date of Defense:
February 15, 2002
Committee Members:
  • Christopher W Churchill, Committee Member
  • Lawrence William Ramsey, Committee Member
  • W Nielsen Brandt, Committee Member
  • Jane Camilla Charlton, Committee Chair
  • Stephane Coutu, Committee Member
  • Michael Eracleous, Committee Member
  • partial coverage
  • quasars
  • multivariate techniques
  • QSOs
  • absorption lines
Work over the last four years in the field of of intrinsic narrow-line absorption in quasars has provided important constraints on the location and origin of the gas and its relationship with observed quasar properties. The contribution from this body of work follows. The gas causing intrinsic narrow absorption lines (intrinsic NALs) is likely to reside either outside the broad emission line region or co-spatial with it. The transverse extent of the absorbing structures are either smaller than the projected size of the UV continuum source or lie relatively close so that photons can be scattered around the absorber and into the line of sight. It is likely that there has been evolution in the number density of strong associated systems such that they are largely absent at low redshift. Weak, associated NALs do not have an out-right preference for radio luminosity at any redshift, with two special cases. In radio-loud QSOs where the disk is oriented face-on (i.e, radio core dominated, flat radio spectrum), associated absorption only appears when the CIV emission line FWHM is large (>6,000 km/s). In radio-quiet QSOs, there is a significant excess of associated weak absorbers in the soft X-ray weak subset. In the select few cases where high resolution spectra exist, it appears that the kinematics of strong and weak absorbers are different. Strong absorbers tend to have smooth troughs indicative of a wind. Weak absorbers tend to have structure implying that the absorbing medium is clumpy along the line of sight. Given the difference between strong and weak associated NALs, it is likely that these form different populations of absorbers. There is likely to be a dynamical link between the gas producing intrinsic NALs and the gas producing the broad emission lines. The peak of the velocity distribution of intrinsic NALs peaks at the redshift of the high ionization emission lines. NALs appear on either side of the emission line peak, but are unlikely to be sufficiently redshift as to imply infalling gas.