Decrease in the space density of quasars at high redshift
Article Abstract:
A survey of radio-loud high-redshift quasars not only shows a sharp decrease in space density for redshifts greater than three but also provides a measure of the galaxy formation and interactions between galaxies. A search of a large sample of flat-spectrum Parkes radio sources from a region covering 40% of the sky reveals the near negligible influence of dust on radio emission from quasars. The high redshift quasars may be distinguished by their Lyman shift/hydrogen-based heavy obscuring in the optical B band. The results assume flat spectra for the very high redshift quasars.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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The cosmological deceleration parameter estimated from the angular-size/redshift relation for compact radio sources
Article Abstract:
Redshift and angular size for selected compact radio sources was determined without interference from evolutionary effects using very-long-baseline interferometry. These radio sources are identified with active galaxies and quasars. Reliable measurement of their redshifts confirmed the inflationary model of the Universe. In addition, the relationship between redshift and angular size suggests that the Universe may be at the critical point between interminable expansion or deceleration.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Identification of faint radio sources with optically luminous interacting disk galaxies
Article Abstract:
In a starburst phase, the microjansky sources (radio sources) are the luminous disk galaxies introduced by interactions or mergers. A majority of the microjansky sources are light blue galaxies having light profiles resembling disk galaxies with starburst or post-starburst natures probably caused by interactions or mergers. About half of these galaxies exist in pairs or small groups.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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