813 research outputs found
Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data
We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of
23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23.
The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha.
Here we provide a detailed description of the data, including careful
spectrophotometry and redshift determination. We also present direct
measurements of the continua, strong emission lines and features, including
Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII],
He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical.
The widths, asymmetries and velocity shifts of profiles of strong emission
lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha.
This suggests that the motion of the broad line region is related to the
ionization structure, but the data appears not agree with the radially
stratified ionization structure supported by reverberation mapping studies, and
therefore suggest that outflows contribute additional velocity components to
the broad emission line profiles.Comment: 42 pages, 10 figures, 13 tables. Accepted by AJ. Supplemental figures
not included. Full version available at
http://physics.uwyo.edu/~shang/pgxpaper/ShangPaper.pd
Discovery of a Radio-loud/Radio-quiet Binary Quasar
We report the discovery of a small separation quasar pair (z=0.586, O=18.4,
19.2, sep. = 2.3 arcsec) associated with the radio source FIRST
J164311.3+315618 (S_1400 = 120 mJy). The spectrum of the brighter quasar (A)
has a much stronger narrow emission-line spectrum than the other (B), and also
stronger Balmer lines relative to the continuum. The continuum ratio of the
spectra is flat in the blue at about 2.1, but falls to 1.5 at longer
wavelengths. A K' image shows two unresolved sources with a flux ratio of 1.3.
The different colors appear to result from the contribution of the host galaxy
of B, which is evident from Ca II and high-order Balmer absorption lines
indicative of a substantial young stellar population. New 3.6 cm VLA
observations show that the compact radio source is coincident with quasar A (B
is only marginally detected). We rule out the lensing hypothesis because the
optical flux ratio is A/B = 1.2 to 2, while the radio flux ratio is A/B > 40,
and conclude that this system is a binary. Moreover, the radio-loud quasar is a
compact steep spectrum source. FIRST J164311.3+315618A, B is the lowest
redshift and smallest separation binary quasar yet identified.Comment: 8 pages, 3 figures, to appear in Astrophysical Journal Letter
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