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Title: Probing variations in fundamental constants with radio and optical quasar absorption-line observations.

Abstract

Nine quasar absorption spectra at 21-cm and ultraviolet (UV) rest-frame wavelengths are used to estimate possible variations in x {triple_bond} {alpha}{sup 2}g{sub p}{mu}, where {alpha} is the fine structure constant, g{sub p} the proton g-factor and {mu} {triple_bond} m{sub e}/m{sub p} is the electron-to-proton mass ratio. We find <{Delta}x/x>{sub total}{sup weighted} = (0.63 {+-} 0.99) x 10{sup -5} over a redshift range 0.23 {le} z{sub abs} {le} 2.35 which corresponds to look-back times of 2.7-10.5 billion years. A linear fit against look-back time, tied to {Delta}x/x = 0 at z = 0, gives a best-fitting rate of change of {dot x}/x = (-0.6 {+-} 1.2) x 10{sup -5} yr{sup -1}. We find no evidence for strong angular variations in x across the sky. Our sample is much larger than most previous samples and demonstrates that intrinsic line-of-sight velocity differences between the 21-cm and UV absorption redshifts, which have a random sign and magnitude in each absorption system, limit our precision. The data directly imply that the average magnitude of this difference is {Delta}v{sub los}-6 km s{sup -1}. Combining our {Delta}x/x measurement with absorption-line constraints on {alpha}-variation yields strong limits on the variation of {mu}. Our most conservative estimate, obtained bymore » assuming no variations in {alpha} or g{sub p} is simply {Delta}{mu}/{mu} = <{Delta}x/x>{sub total}{sup weighted}. If we use only the four high-redshift absorbers in our sample, we obtain {Delta}{mu}/{mu} = (0.58 {+-} 1.95) x 10{sup -5}, which agrees (2{sigma}) with recent, more direct estimates from two absorption systems containing molecular hydrogen, also at high redshift, and which have hinted at a possible {mu}-variation, {Delta}{mu}/{mu} = (-2.0 {+-} 0.6) x 10{sup -5}. Our method of constraining {Delta}{mu}/{mu} is completely independent from the molecular hydrogen observations. If we include the low-redshift systems, our {Delta}{mu}/{mu} result differs significantly from the high-redshift molecular hydrogen results. We detect a dipole variation in {mu} across the sky, but given the sparse angular distribution of quasar sight lines we find that this model is required by the data at only the 88 percent confidence level. Clearly, much larger samples of 21-cm and molecular hydrogen absorbers are required to adequately resolve the issue of the variation of {mu} and x.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); FOR; OUS
OSTI Identifier:
940209
Report Number(s):
ANL/PHY/JA-57314
Journal ID: ISSN 0035-8711; MNRAA4; TRN: US200823%%670
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Mon. Not. R. Astron. Soc.; Journal Volume: 374; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; ABSORPTION; ABSORPTION SPECTRA; ACCURACY; ANGULAR DISTRIBUTION; DIPOLES; FINE STRUCTURE; FUNDAMENTAL CONSTANTS; HYDROGEN; PROTONS; QUASARS; SKY; VELOCITY; WAVELENGTHS

Citation Formats

Tzanavaris, P., Murphy, M. T., Webb, J. K., Flambaum, V. V., Curran, S. J., Physics, Univ. of New South Wales, and Inst. of Astronomy. Probing variations in fundamental constants with radio and optical quasar absorption-line observations.. United States: N. p., 2007. Web. doi:10.1111/j.1365-2966.2006.11178.x.
Tzanavaris, P., Murphy, M. T., Webb, J. K., Flambaum, V. V., Curran, S. J., Physics, Univ. of New South Wales, & Inst. of Astronomy. Probing variations in fundamental constants with radio and optical quasar absorption-line observations.. United States. doi:10.1111/j.1365-2966.2006.11178.x.
Tzanavaris, P., Murphy, M. T., Webb, J. K., Flambaum, V. V., Curran, S. J., Physics, Univ. of New South Wales, and Inst. of Astronomy. Mon . "Probing variations in fundamental constants with radio and optical quasar absorption-line observations.". United States. doi:10.1111/j.1365-2966.2006.11178.x.
@article{osti_940209,
title = {Probing variations in fundamental constants with radio and optical quasar absorption-line observations.},
author = {Tzanavaris, P. and Murphy, M. T. and Webb, J. K. and Flambaum, V. V. and Curran, S. J. and Physics and Univ. of New South Wales and Inst. of Astronomy},
abstractNote = {Nine quasar absorption spectra at 21-cm and ultraviolet (UV) rest-frame wavelengths are used to estimate possible variations in x {triple_bond} {alpha}{sup 2}g{sub p}{mu}, where {alpha} is the fine structure constant, g{sub p} the proton g-factor and {mu} {triple_bond} m{sub e}/m{sub p} is the electron-to-proton mass ratio. We find <{Delta}x/x>{sub total}{sup weighted} = (0.63 {+-} 0.99) x 10{sup -5} over a redshift range 0.23 {le} z{sub abs} {le} 2.35 which corresponds to look-back times of 2.7-10.5 billion years. A linear fit against look-back time, tied to {Delta}x/x = 0 at z = 0, gives a best-fitting rate of change of {dot x}/x = (-0.6 {+-} 1.2) x 10{sup -5} yr{sup -1}. We find no evidence for strong angular variations in x across the sky. Our sample is much larger than most previous samples and demonstrates that intrinsic line-of-sight velocity differences between the 21-cm and UV absorption redshifts, which have a random sign and magnitude in each absorption system, limit our precision. The data directly imply that the average magnitude of this difference is {Delta}v{sub los}-6 km s{sup -1}. Combining our {Delta}x/x measurement with absorption-line constraints on {alpha}-variation yields strong limits on the variation of {mu}. Our most conservative estimate, obtained by assuming no variations in {alpha} or g{sub p} is simply {Delta}{mu}/{mu} = <{Delta}x/x>{sub total}{sup weighted}. If we use only the four high-redshift absorbers in our sample, we obtain {Delta}{mu}/{mu} = (0.58 {+-} 1.95) x 10{sup -5}, which agrees (2{sigma}) with recent, more direct estimates from two absorption systems containing molecular hydrogen, also at high redshift, and which have hinted at a possible {mu}-variation, {Delta}{mu}/{mu} = (-2.0 {+-} 0.6) x 10{sup -5}. Our method of constraining {Delta}{mu}/{mu} is completely independent from the molecular hydrogen observations. If we include the low-redshift systems, our {Delta}{mu}/{mu} result differs significantly from the high-redshift molecular hydrogen results. We detect a dipole variation in {mu} across the sky, but given the sparse angular distribution of quasar sight lines we find that this model is required by the data at only the 88 percent confidence level. Clearly, much larger samples of 21-cm and molecular hydrogen absorbers are required to adequately resolve the issue of the variation of {mu} and x.},
doi = {10.1111/j.1365-2966.2006.11178.x},
journal = {Mon. Not. R. Astron. Soc.},
number = 2007,
volume = 374,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
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