A search for neutral hydrogen absorption in the spectra of quasi-stellar objects

1980 ◽  
Vol 242 ◽  
pp. 879 ◽  
Author(s):  
B. M. Peterson ◽  
C. B. Foltz
Keyword(s):  
Hydrogen Absorption ◽  
Neutral Hydrogen ◽  
Stellar Objects ◽  
Quasi Stellar Objects

Absorption by neutral hydrogen and ionized magnesium in quasi-stellar objects and BL Lacertae objects

1977 ◽  
Vol 218 ◽  
pp. 605 ◽  
Author(s):  
B. M. Peterson ◽  
P. A. Strittmatter ◽  
R. E. Williams ◽  
G. D. Coleman
Keyword(s):  
Neutral Hydrogen ◽  
Bl Lacertae Objects ◽  
Stellar Objects ◽  
Ionized Magnesium ◽  
Bl Lacertae ◽  
Quasi Stellar Objects

scholarly journals The influence of metagalactic ultraviolet background fluctuations on the high-redshift Lyα forest

2019 ◽  
Vol 491 (4) ◽  
pp. 4884-4893 ◽  
Author(s):  
Avery Meiksin
Keyword(s):  
Luminosity Function ◽  
High Redshift ◽  
Spatial Coherence ◽  
Neutral Hydrogen ◽  
Line Of Sight ◽  
Analytic Model ◽  
Broad Distribution ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Autocorrelation Length

ABSTRACT Under the assumption that galaxies and quasi-stellar objects (QSOs) dominate the metagalactic ultraviolet (UV) background, it is shown that at high redshifts, fluctuations in the UV background are dominated by QSO shot noise and have an autocorrelation length of a few to several comoving Mpcs, depending on the bright end of the QSO luminosity function. The correlations create long-range spatial coherence in the neutral hydrogen fraction. Using a semi-analytic model, it is demonstrated that the coherence may account for the broad distribution in effective optical depths measured in the Lyα forest spectra of background QSOs, for line-of-sight segments of comoving length $50\, h^{-1}$ Mpc at redshifts 5 < z < 6. Capturing the fluctuations in a numerical simulation requires a comoving box size of ∼1 Gpc, although a box half this size may be adequate if sufficient random realizations of the QSO population are performed.

The properties of the dusty inner regions of nearby QSOs

2019 ◽  
Vol 15 (S356) ◽  
pp. 95-95
Author(s):  
Itziar Aretxaga
Keyword(s):  
Star Formation ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Stellar Objects ◽  
X Ray ◽  
Mir Spectroscopy ◽  
Polycyclic Aromatic ◽  
Quasi Stellar Objects

AbstractWe present MIR spectroscopy and photometry obtained with CanariCam on the 10.4 m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec. We derive the properties of the dusti tori that surround the nucleus based on these observations and find significant differences in the parameters compared with a sample of Seyfert 1 and 2 nuclei. We also find evidence for polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicative of star formation, more centrally peaked (on scales of a few hundred pc) than previously believed.

scholarly journals Classification of Compact Objects: QSS, QSOs, N-Type and Compact Galaxies, Seyfert and Galactic Nuclei

1972 ◽  
Vol 44 ◽  
pp. 97-103
Author(s):  
W. W. Morgan
Keyword(s):  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Classification Criteria ◽  
Compact Objects ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Compact Galaxies

Some methods currently in use for the classification of the optical forms of the ‘compact’ galaxies and quasi-stellar objects are reviewed. It is shown that the category ‘Seyfert Galaxy’ is basically a spectroscopic (rather than a form) classification.An optical form-classification is described which is, in principle, identical with published classification criteria for QSO, N-type, and compact objects. The importance of maintaining rigid form-standards is emphasized.

On the Space Distribution of Identified Quasi-stellar Objects and Radiogalaxies

Nature ◽  
1967 ◽  
Vol 216 (5113) ◽  
pp. 351-352 ◽  
Author(s):  
G. R. BURBIDGE ◽  
F. HOYLE
Keyword(s):  
Space Distribution ◽  
Stellar Objects ◽  
Quasi Stellar Objects

Nature of strong radio emission from quasi-stellar objects

1964 ◽  
Vol 9 (2) ◽  
pp. 138-139 ◽  
Author(s):  
L. Gold ◽  
J.W. Moffat
Keyword(s):  
Radio Emission ◽  
Stellar Objects ◽  
Quasi Stellar Objects

scholarly journals THE HIGH A V Quasar Survey: Reddened Quasi-Stellar Objects selected from optical/near-infrared photometry. II.

2015 ◽  
Vol 217 (1) ◽  
pp. 5 ◽  
Author(s):  
J.-K. Krogager ◽  
S. Geier ◽  
J. P. U. Fynbo ◽  
B. P. Venemans ◽  
C. Ledoux ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Photometry ◽  
Stellar Objects ◽  
Quasi Stellar Objects

A search for neutral hydrogen absorption in the double quasar 0957 + 561

Nature ◽  
1980 ◽  
Vol 283 (5743) ◽  
pp. 175-176
Author(s):  
C. L. Bennett ◽  
C. R. Lawrence ◽  
B. F. Burke
Keyword(s):  
Hydrogen Absorption ◽  
Neutral Hydrogen
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