Probing the cosmological variation of the fine - structure constant: Results based on VLT - UVES sample

By H. Chand, R. Srianand, P. Petitjean, B. Aracil. 2004

204 citations recorded by the source corpus.

Development of fundamental physics relies on the constancy of various fundamental quantities such as the fine- structure constant. Detecting or constraining the possible time variations of these fundamental physical quantities is an im- portant step toward a complete understanding of basic physics. High-quality absorption lines seen in the spectra of distant QSOs allow one to probe time variations of several of these quantities. Here we present the results from a detailed many- multiplet analysis, to detect the possible variation of the fine-structure constant, performed using high signal-to-noise ratio, (∼70 per pixel), high spectral resolution (R ≥ 45 000) observations of 23 Mg  systems detected toward 18 QSOs in the redshift range 0.4 ≤ z ≤ 2.3 obtained using UVES at the VLT. We validate our procedure and define the selection criteria that will avoid possible systematics using a detailed analysis of a simulated data set. The spectra of Mg  doublets and Fe  multiplets are generated considering variations in α and specifications identical to that of our UVES spectra. We show that our Voigt profile fitting code recovers the variation in α very accurately when we use single component systems and multiple-component systems that are not heavily blended. Spurious detections are frequently seen when we use heavily blended systems or systems with very weak lines. Thus we avoided these system while analysing the UVES data. To make the analysis transparent and accessible to the community for critical scrutiny, all the steps involved in the analysis are presented in detail. The weighted mean value of the variation in α obtained from our analysis over the redshift range 0.4 ≤ z ≤ 2. 3i s∆α/α = (−0.06 ± 0.06) × 10 −5 . The median redshift of our sample is 1.55 and corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. The 3σ upper limit on the time variation of α is −2.5 × 10 −16 yr −1 ≤ (∆α/α∆t) ≤ +1.2 × 10 −16 yr −1 . To our knowledge this is the strongest constraint from quasar absorption line studies to till date.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/464a7623a8ca03b8c52d50199ae8749f9a945f7c

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman α systems: physical conditions in the neutral gas (2005, methodology): “For this, C© 2005 RAS, MNRAS 362, 549–568 552 R. Srianand et al. we use a Voigt-profile fitting code that determines the best-fitting parameters (column density, velocity dispersion and redshift) using χ2 minimization techniques (Chand et al. 2004).”
Spatial variation in the fine-structure constant – new results from VLT/UVES (2012, methodology): “The only other statistical sample to search for a change in α using the MM method is the work of Chand et al. (2004).”
Search for New Physics with Atoms and Molecules (2017, methodology): “However, the analysis of data from 23 absorption systems taken by the Very Large Telescope (VLT) ultraviolet and visual Echelle spectrograph (UVES) yielded a null result ∆α α = (−0.06± 0.06)× 10−5, (20) for 0.4 < z < 2.3 (Chand et al., 2004; Srianand et al., 2004).”
The physics of the intergalactic medium (2007, unknown): “Chand et al. (2004) and Srianand et al. (2004) report ∆α/α = (−0.6± 0.6)× 10−6 over the redshift range 0.4 < z < 2.3.”
Varying Constants, Gravitation and Cosmology (2010, methodology): “To finish, let us mention that [361] reanalyzed some systems of [90, 470] by means of the SIDAM method (see below) and disagree with some of them, claiming for a problem of calibration.”