منابع مشابه
X-ray Surveys of the obscured Universe
Deep X-ray surveys have shown that the cosmic X-ray background (XRB) is largely due to accretion onto supermassive black holes, integrated over cosmic time. However, the characteristic hard spectrum of the XRB can only be explained if most AGN spectra are heavily absorbed. The absorbed AGN will suffer severe extinction and therefore, unlike classical QSOs, will not be prominent at optical wavel...
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Since its beginning in the early 1960s, the field of X-ray astronomy has exploded, experiencing a ten-billion-fold increase in sensitivity, which brought it on par with the most advanced facilities at all wavelengths. I will briefly describe the revolutionary first discoveries prior to the launch of the Chandra and XMM-Newton X-ray observatories, present some of the current achievements, and of...
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We describe an ongoing experiment to search for the meta-galactic Lymancontinuum background at z ≈ 2 − 3. We are obtaining one of the deepest optical spectra ever, using LRIS/Keck-II to search for the fluorescent Ly-α emission from optically thick H I clouds. The null results of our pilot study (Bunker, Marleau & Graham 1998) placed a 3σ upper bound on the mean intensity of the ionizing backgro...
متن کاملOur Second Look at the Immature Universe: The Infrared View
The long-awaited promise of studying high-redshift galaxies at long wavelengths has been partially eclipsed by progress at optical wavelengths, mostly because of the number of available pixels. It is nonetheless essential to study optically selected high-redshift galaxies at wavelengths longward of 1 μm, for several reasons. One of the indications from such studies to date is that interstellar ...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2001
ISSN: 0004-637X
DOI: 10.1086/324014