High-resolution spectroscopy of selected absorption lines toward quasi-stellar objects. I - Lyman-alpha toward PHL 957

1983 ◽  
Vol 267 ◽  
pp. 12 ◽  
Author(s):  
F. H., Jr. Chaffee ◽  
R. J. Weymann ◽  
P. A. Strittmatter ◽  
D. W. Latham
Keyword(s):  
High Resolution ◽  
Absorption Lines ◽  
High Resolution Spectroscopy ◽  
Stellar Objects ◽  
Lyman Alpha ◽  
Quasi Stellar Objects

High Resolution Spectroscopy of Absorption Lines in the Z = 1.7 BL LAC Object 0215+015

Quasars ◽  
1986 ◽  
pp. 571-572
Author(s):  
J. Chris Blades ◽  
Richard W. Hunstead ◽  
Hugh S. Murdoch ◽  
Max Pettini
Keyword(s):  
High Resolution ◽  
Absorption Lines ◽  
High Resolution Spectroscopy ◽  
Bl Lac

Absorption lines in the spectra of low-redshift quasi-stellar objects

1978 ◽  
Vol 226 ◽  
pp. 21 ◽  
Author(s):  
B. M. Peterson ◽  
P. A. Strittmatter
Keyword(s):  
Absorption Lines ◽  
Stellar Objects ◽  
Quasi Stellar Objects

Optical spectroscopy of BL Lac objects: TeV candidates

2020 ◽  
Vol 497 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Simona Paiano ◽  
Renato Falomo ◽  
Aldo Treves ◽  
Riccardo Scarpa
Keyword(s):  
Lower Limit ◽  
Gamma Ray ◽  
Absorption Lines ◽  
Host Galaxies ◽  
Stellar Objects ◽  
Bl Lac Objects ◽  
Forbidden Transition ◽  
Bl Lac ◽  
Quasi Stellar Objects ◽  
Relationship Of

ABSTRACT We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT Sources and that are good candidates as TeV emitters. We focus on the 91 sources that are labelled by the Fermi team as BL Lac (BLL) objects or blazar candidates of uncertain type (BCUs), are in the Northern hemisphere, and are with unknown or uncertain redshift. We report here on GTC (Gran Telescopio Canarias) spectra (in the spectral range 4100–7750 Å) of 13 BCUs and 42 BLL objects. We are able to classify the observed targets as BLL objects and each source is briefly discussed. The spectra allowed us to determine the redshift of 25 objects on the basis of emission and/or absorption lines, finding 0.05 < z < 0.91. Most of the emission lines detected are due to forbidden transition of [O iii] and [N ii]. The observed line luminosity is found to be lower than that of quasi-stellar objects (QSOs) at similar continuum and could be reconciled with the line–continuum luminosity relationship of QSOs if a significant beaming factor is assumed. Moreover, for five sources we found intervening absorption lines that allow to set a spectroscopic lower limit of the redshift. For the remaining 25 sources, for which the spectra are lineless, a lower limit to z is given, assuming that the host galaxies are giant ellipticals.

Absorption Lines in Quasi-stellar Objects

Nature ◽  
1967 ◽  
Vol 216 (5120) ◽  
pp. 1092-1092 ◽  
Author(s):  
G. R. BURBIDGE ◽  
E. M. BURBIDGE
Keyword(s):  
Absorption Lines ◽  
Stellar Objects ◽  
Quasi Stellar Objects

scholarly journals Sizes of Intervening C IV Absorbers from High Resolution Spectroscopy of APM 0827+5255

2004 ◽  
Vol 217 ◽  
pp. 272-274
Author(s):  
Panayiotis Tzanavaris ◽  
Robert F. Carswell
Keyword(s):  
High Resolution ◽  
Lower Limit ◽  
Absorption Lines ◽  
High Resolution Spectroscopy ◽  
Line Of Sight ◽  
Total Coverage ◽  
Best Estimates

Some intervening C IV absorbers in the Keck/HIRES spectrum of APM 0827+5255 give rise to absorption lines for which the observed optical depths for the doublet components are not in the expected 2 : 1 ratio. We model this effect as coverage of one line of sight to this gravitationally lensed quasar and perform a set of simulations to select a sample of lines for which our model provides an explanation for the effect. We use lines in this sample to obtain estimates for minimum absorber sizes from total coverage and the separations of the lines of sight for a range of lens redshifts, z1, and two cosmologies. We also obtain best estimates for overall sizes from a statistical “hit and miss” approach. For z1 = 0.7 our results set a lower limit to sizes of C IV absorbers of ~ 0.3 h−172 kpc (~ 0.5 h−172 kpc) for ΩM = 1, ΩA = 0 (ΩM = 0.3, ΩA = 0.7).

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