scholarly journals Limits on the Variation of Physical Constants Derived from Molecular Absorption Lines

1999 ◽  
Vol 183 ◽  
pp. 167-167 ◽  
Author(s):  
T. Wiklind ◽  
F. Combes
Keyword(s):  
Absorption Line ◽  
High Redshift ◽  
Absorption Lines ◽  
Frequency Resolution ◽  
Radio Lines ◽  
Molecular Absorption ◽  
Diagnostic Application ◽  
Physical Constants ◽  
Resonance Transitions ◽  
Electronic Resonance

A potential diagnostic application of molecular rotational absorption lines at high redshift is to test the invariance of physical constants. This can be done by comparing the observed redshifted frequency of a molecular absorption line with redshifted lines from other types of transitions such as the 21cm hyperfine transition or electronic resonance transitions. In order to set stringent limits, it is necessary to achieve the greatest possible frequency resolution. This makes radio lines well suited for this purpose.

scholarly journals Molecular Absorption Lines in Galaxies

2005 ◽  
Vol 13 ◽  
pp. 839-844
Author(s):  
Tommy Wiklind
Keyword(s):  
Interstellar Medium ◽  
Absorption Line ◽  
Molecular Species ◽  
High Redshift ◽  
Detailed Comparison ◽  
Absorption Lines ◽  
Molecular Gas ◽  
Molecular Absorption ◽  
First Order ◽  
Nearby Galaxies

AbstractMolecular absorption lines have become an important tool in studying the astrochemistry of the dense and cold interstellar medium in both our own Galaxy and high redshift systems. The sensitivity is to first order only dependent on the observed continuum flux. Apart from a few nearby galaxies, molecular absorption lines have been used to study the molecular ISM in 4 galaxies at redshifts 0.25-0.89. A large number of molecular species and transitions have been observed, allowing a detailed comparison with molecular gas in our own Galaxy. Planned instruments, such as ALMA, will allow studies of a larger number of molecular absorption line systems.

Resonance Broadening and Oscillator strength of the Mercury Absorption Line 1850 Å

1975 ◽  
Vol 30 (4) ◽  
pp. 445-450 ◽  
Author(s):  
D. Gebhard ◽  
W. Behmenburg
Keyword(s):  
Absorption Line ◽  
Oscillator Strength ◽  
Resonance Absorption ◽  
New Method ◽  
Absorption Lines ◽  
Resonance Transition ◽  
Resonance Transitions ◽  
Resonance Broadening

Abstract A new method for the determination of f-values of resonance transitions from wing-measurements of selfbroadened resonance absorption lines is described. The method is applied to the mercury resonance transition 61 S0→61P1, λ 1850 Å. The resulting f-value of 1.08±0.05 agrees well with those obtained from other methods.

scholarly journals Absorption Systems in High Redshift QSOs

1977 ◽  
Vol 74 ◽  
pp. 193-222 ◽  
Author(s):  
A. Boksenberg
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
High Redshift ◽  
Ground Level ◽  
Emission Lines ◽  
Absorption Lines ◽  
Absorption System ◽  
Characteristic Emission

In addition to the characteristic emission lines, absorption lines frequently are seen in the spectra of QSOs, usually those with high redshift (zem ≳ 1.8). About 10 percent of all QSOs listed in the compilation of Burbidge et al. (1976a) are recorded as having at least one ‘identified’ absorption system, meaning that a pattern of several selected observed lines can be matched with the apparent wavelengths of transitions (generally from the ground level) in a physical plausible group of atoms or ions at the same, although arbitrary, redshift (Bahcall 1968, Aaronson et al. 1975). Identified absorption line redshifts range from being comparable with the associated emission line redshifts, to having very much smaller values with relative velocities exceeding 0.5c in the QSO frame. Added to this, there are many QSOs having absorption lines not yet recognised as belonging to identified systems, both those objects already having one or more identifications, and others with none.

scholarly journals Molecular QSO Absorption Line Systems

2002 ◽  
Vol 12 ◽  
pp. 481-484 ◽  
Author(s):  
C.L. Carilli ◽  
K.M. Menten
Keyword(s):  
Absorption Line ◽  
High Redshift ◽  
Gravitational Lenses ◽  
Molecular Absorption

AbstractWe review observations of molecular absorption line systems at high redshift toward red quasars and gravitational lenses.

scholarly journals 21cm Absorption Lines at High Redshift from Intervening Galaxies

2002 ◽  
Vol 199 ◽  
pp. 83-90 ◽  
Author(s):  
F. H. Briggs
Keyword(s):  
Absorption Line ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Radio Galaxies ◽  
Hydrogen Gas ◽  
Absorption Lines ◽  
Radio Sources ◽  
Evolution Of Galaxies ◽  
Neutral Gas ◽  
Extended Radio

Radio absorption line observations of neutral hydrogen gas against extended radio sources offers the means to measure sizes and kinematics in intervening galaxies at all redshifts up to the maximum redshift where radio galaxies are detected. Such observations can therefore trace the evolution of galaxies at redshifts z ≳ 2 where the damped Lyman — α statistics indicate that the mass in neutral gas exceeded the mass in stars.

scholarly journals Absorption-Line Spectroscopy of Close Pairs of QSOs

1983 ◽  
Vol 104 ◽  
pp. 369-370
Author(s):  
P. A. Shaver ◽  
J. G. Robertson
Keyword(s):  
Absorption Line ◽  
Cross Sections ◽  
High Redshift ◽  
The Other ◽  
Absorption Lines ◽  
Clusters Of Galaxies ◽  
Absorption Cross ◽  
Powerful Approach ◽  
Metal Absorption ◽  
Close Pairs

Close pairs of QSOs (separations ≲ 1–5 arcmin) provide a powerful approach to the study of narrow absorption lines in QSO spectra. By looking for absorption in the spectrum of the higher-redshift QSO at the redshift of the other (“associated absorption”), or absorption in both spectra at the same redshift (“common absorption”), one may address several issues: the cosmological nature of QSO redshifts, the origin of the narrow absorption lines of high redshift and excitation (intrinsic or intervening), the clustering of absorbing systems (with each other, and with QSOs), the sizes of the absorbing regions (for metal absorption lines and for Lyα lines; absorption cross-sections of individual galaxies and of clusters of galaxies), and the presence and nature of gaseous halos around QSOs.

scholarly journals Evolution of the EUV Background from Quasar Absorption Line Studies

1996 ◽  
Vol 168 ◽  
pp. 237-244
Author(s):  
Jill Bechtold
Keyword(s):  
Ionizing Radiation ◽  
Absorption Line ◽  
Radiation Field ◽  
Proximity Effect ◽  
Reasonable Agreement ◽  
Extreme Ultraviolet ◽  
High Redshift ◽  
Absorption Lines ◽  
Quasar Absorption Lines ◽  
Quasar Spectra

The integrated extreme ultraviolet (EUV) radiation from quasars and other high redshift sources provides an ambient ionizing radiation field which may photoionize the gas seen as quasar absorption lines. In particular, the observed evolution of the Lyα forest clouds probably results in part from the evolution of the EUV metagalactic field. Estimates of the EUV field as a function of redshift can be made from measuring the “proximity effect” in quasar spectra; uncertainties in these estimates may be large. Given the uncertainties, the estimated EUV field at z≈3 derived from the proximity effect is in reasonable agreement with the expected contribution from luminous quasars.

Submegahertz frequency stabilization of a terahertz quantum cascade laser to a molecular absorption line

2010 ◽  
Vol 96 (7) ◽  
pp. 071112 ◽  
Author(s):  
H. Richter ◽  
S. G. Pavlov ◽  
A. D. Semenov ◽  
L. Mahler ◽  
A. Tredicucci ◽  
...  
Keyword(s):  
Absorption Line ◽  
Quantum Cascade Laser ◽  
Frequency Stabilization ◽  
Molecular Absorption ◽  
Quantum Cascade

Dust-reddened Quasars

1996 ◽  
Vol 13 (2) ◽  
pp. 183-184 ◽  
Author(s):  
M. J. Drinkwater ◽  
R. L. Webster ◽  
P. J. Francis ◽  
T. Wiklind ◽  
F. Combes
Keyword(s):  
Molecular Clouds ◽  
Physical State ◽  
Absorption Lines ◽  
Line Of Sight ◽  
Host Galaxy ◽  
Molecular Gas ◽  
Molecular Absorption

We have recently discovered evidence for a population of radio-loud quasars that is reddened by dust. The dust is either along the line of sight to the quasars or is associated with the quasars. In the latter case the dust may be in molecular clouds in the quasar’s host galaxy, or in a molecular torus around the nucleus. We are planning to use 3 mm observations to search for molecular absorption lines (CO and HCO+) associated with dust at the redshift of these quasars. If any absorption systems are detected we will be able to deduce detailed information about the physical state of the molecular gas, hopefully showing which of the proposed locations of the dust is most likely.

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