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Date and Time of the Query: 2019-06-20 T12:09:26 PDT
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For refcode 1999ApJ...517L..73M:
Retrieve 22 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1999ApJ...517L..73M Redshifted and Blueshifted Broad Lines in Luminous Quasars D. H. MCINTOSH, H.-W. RIX, M. J. RIEKE, AND C. B. FOLTZ Received 1999 January 19; accepted 1999 March 30; published 1999 April 14 ABSTRACT We have observed a sample of 22 luminous quasars, in the range 2.0 <~z<~2.5, at 1.6 microns with the near-infrared (NIR) spectrograph FSPEC on the Multiple Mirror Telescope. Our sample contains 13 radio-loud and nine radio-quiet objects. We have measured the systemic redshifts z_sys_, directly from the strong [O III] {lambda}5007 line emitted from the narrow- line region. From the same spectra, we have found that the nonresonance broad H{beta} lines have a systematic mean redward shift of 520+/-80 km s^- 1^ with respect to systemic. Such a shift was not found in our identical analysis of the low-redshift sample of Boroson & Green. The amplitude of this redshift is comparable to half the expected gravitational redshift and transverse Doppler effects and is consistent with a correlation between redshift differences and quasar luminosity. From data in the literature, we confirm that the high-ionization rest-frame ultraviolet broad lines are blueshifted ~550-1050 km s^-1^ from systemic and that these velocity shifts systematically increase with ionization potential. Our results allow us to quantify the known bias in estimating the ionizing flux from the intergalactic medium J_{nu}_^IGM^ via the proximity effect. Using redshift measurements commonly determined from strong broad-line species, like Ly{alpha} or C IV {lambda}1549, results in an overestimation of J_{nu}_^IGM^ by factors of ~1.9-2.3. Similarly, corresponding lower limits on the density of baryons {OMEGA}_b_ will be overestimated by factors of ~1.4-1.5. However, the low-ionization Mg II {lambda}2798 broad line is within ~50 km s^-1^ of systemic and thus would be the line of choice for determining the true redshift of 1.0<z<2.2 quasars without NIR spectroscopy and z>3.1 objects using NIR spectroscopy. Subject headings: cosmology: miscellaneous-infrared: general -quasars: emission lines-quasars: general-relativity
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