Document Detail

Magnification of light from many distant quasars by gravitational lenses.
MedLine Citation:
PMID:  12087397     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Exceptionally bright quasars with redshifts up to z = 6.28 have recently been discovered. Quasars are thought to be powered by the accretion of gas onto supermassive black holes at the centres of galaxies. Their maximum (Eddington) luminosity depends on the mass of the black hole, and the brighter quasars are inferred to have black holes with masses of more than a few billion solar masses. The existence of such massive black holes poses a challenge to models for the formation of structures in the early Universe, as it requires their formation within one billion years of the Big Bang. Here we show that up to one-third of known quasars with z approximately equal to 6 will have had their observed flux magnified by a factor of ten or more, as a consequence of gravitational lensing by galaxies along the line of sight. The inferred abundance of quasar host galaxies, as well as the luminosity density provided by the quasars, has therefore been substantially overestimated.
J Stuart B Wyithe; Abraham Loeb
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Nature     Volume:  417     ISSN:  0028-0836     ISO Abbreviation:  Nature     Publication Date:  2002 Jun 
Date Detail:
Created Date:  2002-06-27     Completed Date:  2002-07-19     Revised Date:  2003-11-03    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  923-5     Citation Subset:  -    
Astronomy Department, Harvard University, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
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