Optical Emission-line Properties Research Articles

On the relation of the X-ray and emission-line properties of low-redshift QSOs

view Abstract Citations (24) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the relation of the X-ray and emission-line properties of low-redshift QSOs. Corbin, Michael R. Abstract Comparison of the optical emission-line properties of 55 low-redshift (z less than 0.5) QSOs with their 2 keV X-ray luminosities has revealed two previously unseen correlations. The asymmetry of the H-beta profile and the ratio of the emission in the Fe II complex at 4550 A to that in H-beta are strongly correlated with X-ray luminosity, while correlations between X-ray luminosity and other line parameters, including the Fe II equivalent width, are probable. These correlations do not seem to be attributable to orientation effects and appear to be followed by both radio-loud and radio-quiet objects. Consistent with photoionization models, these results suggest that there exists an X-ray-absorbing region in the broad-line clouds in which Fe II emission arises from collisional excitation. A contribution to the H-beta emission from collisional excitation in the same region may also explain the H-beta asymmetry/X-ray luminosity correlation, as well as low Ly-alpha/H-beta intensity ratios. Publication: The Astrophysical Journal Pub Date: January 1993 DOI: 10.1086/186709 Bibcode: 1993ApJ...403L...9C Keywords: Emission Spectra; Quasars; Red Shift; X Ray Spectra; H Beta Line; Luminosity; Spectral Line Width; Astrophysics full text sources ADS | data products SIMBAD (5)

Optical line-emitting gas and radio emission: evidence for correlation in low-luminosity radio galaxies*

Narrow-band Hα + [N II] images of a sample of low-luminosity B2 radio sources are used to investigate the correlations between radio and optical emission-line properties. It is shown that the correlation between radio and emission-line luminosity, previously established for high-power radio galaxies, extends over five decades in radio luminosity and includes the low radio power sources. It is also shown that the compact radio sources have emission-line excesses relative to the other sources in the sample of the same radio power, as well as far-infrared emission characteristics of emission from cool dust.

Optical emission-line properties of evolved galactic supernova remnants

New optical spectrophotometric data are presented for the supernova remnants CTB 1, OA 184, VRO 42.05.01, S147, the Monoceros Loop, G206.9 + 2.3, and G65.3 + 5.7. These data are combined with published spectral data to study some of the general properties of evolved galactic supernova remnants. It is found that (1) O I and O II forbidden line strengths, when used in conjunction with the usual H-alpha S II forbidden line ratio test, provide an excellent additional diagnostic for discriminating remnants from H II regions; (2) the line ratios H-alpha forbidden line N II, H-alpha forbidden line S II, and forbidden line S II 6717/6731 A generally do not vary substantially among the filaments of an individual remnant; and (3) the observed correlation of forbidden line N II/H-alpha with S II forbidden line 6717/6731 A in remnants is the result of observational selection rather than of evolutionary effects. A galactic nitrogen abundance gradient of d log (N/H)/dR = -0.088 dex/kpc, which is in agreement with that derived from H II regions. However, no abundance gradients for oxygen or sulfur are indicated from the remnant data.