Spectral absorption features in active galactic nuclei (AGNs) have traditionally been attributed to outflowing photoionized gas located at a distance of order a parsec from the central continuum source. However, recent observations of QSO FIRST J104459.6+365605 by de Kool and coworkers, when intepreted in the context of a single-phase gas model, imply that the absorption occurs much farther (≈ ...

Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique ...

We report the near-IR detection of a prominent CIV absorption in the rest-frame UV spectrum of the most distant known QSO, SDSS J104433.04−012502.2, at z = 5.80. This QSO was recently observed with XMM-Newton and it was found to be notably X-ray weak. The equivalent width of the CIV absorption feature (∼10Å) strongly supports the idea that the X-ray faintness of this QSO is due to heavy absorpt...

We used Arecibo Observatory and the Green Bank Telescope to observe OH in 12 earlytype galaxies with known reservoirs of dense gas. We present three new detections of OH in absorption in the 1667 MHz line. One objective of our survey was to find evidence of molecular outflows, but our sensitivity and the strength of the OH absorption were insufficient to detect outflows. The detected sources ha...

Increasing demand for field instruments designed to measure gas composition has strongly promoted the development of robust, miniaturized and low-cost handheld absorption spectrometers in the mid-infrared. Efforts thus far have focused on miniaturizing individual components. However, the optical absorption path that the light beam travels through the sample defines the length of the gas cell an...

Simulations and designs are presented of conventional periodic SO2 absorption from exhaust gases using salt water as solvent. Operating conditions resemble those a maritime operation, involving relatively small amounts SO2, so the separation is in linear region. The advantages already demonstrated for distillation remain valid processes: Less tall towers, than staged towers possible, or substan...

In the local universe, most QSO absorption-lines seem to arise from gas in extended 100 kpc halos around spiral galaxies. We present evidence that at high redshift, at least some absorption lines come from diierent sources: the gas is associated not with spiral galaxy halos but with the intra-cluster medium of proto-galaxy clusters. This gas, which is neutral and lumpy, may form a true intra-cl...

A correlation spectroscopy (COSPEC) based on a multiwavelength fiber laser is first proposed for the detection of gas concentration. The lasing wavelengths are selected to match several characteristic absorption peaks of the gas under test, and the gas concentration is easily measured by correlating it with the reference gas. The present method is immune from the instability of the light source...