Observational studies on high-redshift quasars
نویسندگان
چکیده
منابع مشابه
High - 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 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 کاملHighly Accreting Quasars at High Redshift
1 Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada, Spain, 2 INAF, Osservatorio Astronomico di Padova, Padova, Italy, 3 CONACYT Research Fellow, Instituto de Astronomía, Universidad Nacional Autónoma de México, Mexico City, Mexico, 4 Instituto de Astronomía, Universidad Nacional Autónoma de México, Mexico City, Mexico, 5 Dipartimento di Fisica Astronomia “Galileo Galilei”, University of...
متن کاملHigh Redshift Quasars , Emission Lines and ‘ Cloudy ’
I describe some of the outstanding “big picture” questions in quasar research and how the development of the plasma simulation code Cloudy is being guided to answer them. QSO spectra are complex and challenge even the most sophisticated spectral codes. Particular emphasis is given to a central question – how do the properties of the central black hole and the accretion disk are manifested in th...
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ژورنال
عنوان ژورنال: Chinese Science Bulletin
سال: 2015
ISSN: 0023-074X
DOI: 10.1360/n972015-00430