Science-advisor
REGISTER info/FAQ
Login
username
password
     
forgot password?
register here
 
Research articles
  search articles
  reviews guidelines
  reviews
  articles index
My Pages
my alerts
  my messages
  my reviews
  my favorites
 
 
Stat
Members: 3643
Articles: 2'487'895
Articles rated: 2609

28 March 2024
 
  » » arxiv » 104543

 Article forum


Improved constraints on possible variation of physical constants from H I 21cm and molecular QSO absorption lines
M. T. Murphy ; J. K. Webb ; V. V. Flambaum ; M. J. Drinkwater ; F. Combes ; T. Wiklind ;
Date 29 Dec 2000
Journal Mon.Not.Roy.Astron.Soc. 327 (2001) 1244
Subject astro-ph
AffiliationUNSW), J. K. Webb (UNSW), V. V. Flambaum (UNSW), M. J. Drinkwater (UMelb), F. Combes (Paris Obs.), T. Wiklind (OSO
AbstractQSO absorption spectra provide an extremely useful probe of possible cosmological variation in various physical constants. Comparison of H I 21cm absorption with corresponding molecular (rotational) absorption spectra allows us to constrain variation in y=alpha^2*g_p where alpha is the fine structure constant and g_p is the proton g-factor. We analyse spectra of two QSOs, PKS 1413+135 and TXS 0218+357, and derive values of dy/y at absorption redshifts of z=0.2467 and 0.6847 by simultaneous fitting of the H I 21cm and molecular lines. We find dy/y=(-0.20 +/- 0.44)*10^{-5} and dy/y=(-0.16 +/- 0.54)*10^{-5} respectively, indicating an insignificantly smaller y in the past. We compare our results with other recent constraints from the same two QSOs (Drinkwater et al. 1998; Carilli et al. 2000) and with our recent optical constraints which indicated a smaller alpha at higher redshifts.
Source arXiv, astro-ph/0101519
Services Forum | Review | PDF | Favorites   
 

No message found in this article forum.  You have a question or message about this article? Ask the community and write a message in the forum.
If you want to rate this article, please use the review section..

Subject of your forum message:
Write your forum message below (min 50, max 2000 characters)

2000 characters left.
Please, read carefully your message since you cannot modify it after submitting.

  To add a message in the forum, you need to login or register first. (free): registration page






ScienXe.org
» my Online CV
» Free


News, job offers and information for researchers and scientists:
home  |  contact  |  terms of use  |  sitemap
Copyright © 2005-2024 - Scimetrica