Unified model for quasar absorption line systems
نویسندگان
چکیده
منابع مشابه
Is X-ray Absorption from Quasar Absorption Line Systems Detectable?
Using the known properties and statistics of intervening quasar absorption systems, we calculate the cumulative absorption out to high redshifts at soft X-ray (E < 1 keV) energies. Although photoelectric absorption in quasar absorption systems provides a signiicant source of opacity at the lowest X-ray energies, the imprint of this absorption is not readily observable since it is generally mask...
متن کاملA Balmer-line Broad Absorption Line Quasar
I report the discovery of blueshifted broad absorption line (BAL) troughs in at least six transitions of the Balmer series of hydrogen (Hβ to H9) and in Ca II, Mg II and excited Fe II in the quasar SDSS J125942.80+121312.6. This is only the fourth active galactic nucleus known to exhibit Balmer absorption, all four in conjunction with low-ionization BAL systems containing excited Fe II. The sub...
متن کاملA Study of Quasar Absorption Line Systems with IRAS
A survey of quasar absorbers was conducted using the Infrared Astronomical Satellite (IRAS) database. Quasars with known intervening absorption-line systems and broad absorption line (BAL) QSOs were selected primarily from the Junkkarinen, Hewitt & Burbidge catalog (1991). Of the 570 quasars with IRAS data, 52 showed 3 or better detections in at least one band in SCANPI analysis. The origin of ...
متن کاملConstraining fundamental constants of physics with quasar absorption line systems
We summarize the attempts by our group and others to derive constraints on variations of fundamental constants over cosmic time using quasar absorption lines. Most upper limits reside in the range 0.5−1.5×10−5 at the 3σ level over a redshift range of approximately 0.5 − 2.5 for the fine-structure constant, α, the proton-to-electron mass ratio, μ and a combination of the proton gyromagnetic fact...
متن کاملOn the Importance of Local Sources of Radiation for Quasar Absorption Line Systems
A generic assumption of ionization models of quasar absorption systems is that radiation from local sources is negligible compared with the cosmological background. We test this assumption and find that it is unlikely to hold for absorbers as rare as H I Lyman limit systems. Assuming that the absorption systems are gas clouds centered on sources of radiation, we derive analytic estimates for th...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2001
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20010658