Variability of optically selected high redshift quasars
نویسندگان
چکیده
منابع مشابه
Hidden Blazars and Emission Line Variability of High Redshift Quasars
El resumen será traducido al español por los editores. We have carried out a survey to search for hidden blazars in a sample of z∼2 radio-loud quasars. The idea is based on our prediction that we should be able to see large CIV line variability not associated with observed continuum variations or most other emission lines in every radio-loud quasar. Here we report the initial results including ...
متن کاملHigh - redshift obscured quasars
Using mid-infrared and radio criteria, we select a sample of candidate z ∼ 2 obscured quasars. Optical spectroscopy confirms about half of these as type-2 quasars, and modelling the population suggests 50-80% of the quasars are obscured. We find some flat radio spectrum type-2 quasars, and tentative evidence for obscuration unrelated to the torus. Using a similar sample, we also find evidence f...
متن کاملHigh-Redshift, Radio-Loud Quasars
I discuss two programs to study radio-loud quasars at high (z ∼ > 4) redshift. Quasars are the most luminous, non-transient objects known and are observed to the earliest cosmic epochs. At lower redshifts, radio-loud quasars are associated with host galaxies having de Vaucoleurs profiles. By association, identifying and studying a sample of high-redshift, radio-loud quasars provides important c...
متن کاملThe Near-infrared Variability of a Sample of Optically Selected Quasars
A complete sample of 108 optically selected quasars, the Palomar-Green quasars, has been studied at near-infrared wavelengths over an average time base of about 6 yr; in some cases the time base extends to 20 yr. The measurements show that about half the quasars have a high probability of having varied, but that half show little evidence of variability, in sharp contrast to published studies in...
متن کاملXMM - Newton spectroscopy of high - redshift quasars
XMM-Newton observations of 29 high redshift (z>2) quasars, including seven radio-quiet, 16 radio-loud and six Broad Absorption Line (BAL) objects, are presented; due to the high redshifts, the rest-frame energy bands extend up to ∼ 30–70 keV. Over 2–10 keV, the quasars can be well fitted in each case by a simple power-law, with no strong evidence for iron emission lines. The lack of iron lines ...
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: Monthly Notices of the Royal Astronomical Society
سال: 1983
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/203.4.935