The authors thank SAO/NASA ADS Astronomy Abstract Service and American Astronomical Society for their deposit authorization. The original publication can be found in the Astrophysical Journal.
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GALACTIC MASS; GRAVITATIONAL LENSES; LYMAN ALPHA RADIATION; QUASARS; RED SHIFT; ABSORPTION SPECTRA; HEAVY ELEMENTS; HUBBLE CONSTANT; LINE SPECTRA; MONTE CARLO METHOD; ASTRONOMICAL SPECTROSCOPY
Abstract :
[en] The Ly-alpha forest spectra obtained for the A and B images of the gravitationally lensed high-redshift quasar UM 673 are investigated, and higher resolution data of the brightest (A) image are presented. In the 2-A resolution spectra, all the absorption lines detected at 5 sigma in the spectrum of the fainter B image are present in the A image, but two anticoincidences, i.e., two lines in A which do not have a counterpart in B at more than a 3-sigma confidence level, are detected. Given the fact that corresponding Ly-alpha lines in the spectra of A and B have their equivalent widths well correlated, this proves that both light beams actually cross the same clouds. Most of the velocity differences between corresponding lines are compatible with 0 km/s within the error bars, with a standard deviation of 17 km/s. For the two major heavy-element systems detected in the spectrum of UM 673, no significant difference between the corresponding lines in the two spectra are found.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Smette, A.; European Southern Observatory, Santiago, Chile
Surdej, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Shaver, P. A.; European Southern Observatory, Garching, Federal Republic of Germany
Foltz, C. B.; Multiple Mirror Telescope Observatory ; Arizona, University. Tucson, AZ
Chaffee, F. H.; Multiple Mirror Telescope Observatory ; Arizona, University. Tucson, AZ
Weymann, R. J.; Carnegie Institution of Washington, Observatories, Pasadena, CA
Williams, R. E.; Observatorio Interamericano de Cerro Tololo, La Serena, Chile
Magain, Pierre ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Language :
English
Title :
A spectroscopic study of UM 673 A and B - On the size of Lyman-alpha clouds
Publication date :
10 April 1992
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
University of Chicago Press, Chicago, United States - Illinois
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