New constraint on cosmological variation of the proton-to-electron mass ratio from Q0528−250 (original) (raw)
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Monthly Notices of the Royal Astronomical Society, 2012
Molecular hydrogen (H 2 ) absorption features observed in the line-of-sight to Q2348−011 at redshift z abs 2.426 are analysed for the purpose of detecting a possible variation of the proton-to-electron mass ratio µ ≡ m p /m e . By its structure Q2348−011 is the most complex analysed H 2 absorption system at high redshift so far, featuring at least seven distinctly visible molecular velocity components. The multiple velocity components associated with each transition of H 2 were modeled simultaneously by means of a comprehensive fitting method. The fiducial model resulted in ∆µ/µ = (−0.68 ± 2.78) × 10 −5 , showing no sign that µ in this particular absorber is different from its current laboratory value. Although not as tight a constraint as other absorbers have recently provided, this result is consistent with the results from all previously analysed H 2 -bearing sight-lines. Combining all such measurements yields a constraint of |∆µ/µ| 10 −5 for the redshift range z = (2-3).
H2/HD molecular data for analysis of quasar spectra in search of varying constants
Astronomy & Astrophysics
Context. Absorption lines of H2 and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio μ. For this purpose, results from astronomical observations are compared with a compilation of molecular data of the highest accuracy, obtained in laboratory studies as well as in first-principles calculations. Aims. A comprehensive line list is compiled for H2 and HD absorption lines in the Lyman (B1Σu+ − X1Σg+) and Werner (C1Πu − X1Σg+) band systems up to the Lyman cutoff at 912 Å. Molecular parameters listed for each line i are the transition wavelength λi, the line oscillator strength fi, the radiative damping parameter of the excited state Γi, and the sensitivity coefficient Ki for a variation of the proton-to-electron mass ratio. Methods. The transition wavelengths λi for the H2 and HD molecules are determined by a variety of advanced high-precision spectroscopic experiments involving narr...
Search for Cosmological μ-Variation from High-Redshift H2 Absorption; A Status Report
Astrophysics and Space Science Proceedings, 2011
Observations of H 2 spectra in the line-of-sight of distant quasars may reveal a variation of the proton-electron mass ratio µ = m p /m e at high redshift, typically for z > 2. Currently four high-quality systems (Q0347−383, Q0405−443, Q0528 − 250 and J2123 − 005) have been analyzed returning a constraint ∆ µ/µ < 1 × 10 −5 . We present data and a µ-variation analysis of another system, Q2348 − 011 at redshift z abs = 2.42, delivering ∆ µ/µ = (−1.5 ± 1.6) × 10 −5 . In addition to observational data the status of the laboratory measurements is reviewed. The future possibilities of deriving a competitive constraint on ∆ µ/µ from the known high-redshift H 2 absorbers is investigated, resulting in the identification of a number of potentially useful systems for detecting µ-variation.
New limit on a varying proton-to-electron mass ratio from high-resolution optical quasar spectra
2010
Molecular transitions recently discovered at redshift z_abs=2.059 toward the bright background quasar J2123-0050 are analysed to limit cosmological variation in the proton-to-electron mass ratio, mu=m_p/m_e. Observed with the Keck telescope, the optical spectrum has the highest resolving power and largest number (86) of H_2 transitions in such analyses so far. Also, (7) HD transitions are used for the first time to constrain mu-variation. These factors, and an analysis employing the fewest possible free parameters, strongly constrain mu's relative deviation from the current laboratory value: dmu/mu =(+5.6+/-5.5_stat+/-2.7_sys)x10^{-6}. This is the first Keck result to complement recent constraints from three systems at z_abs>2.5 observed with the Very Large Telescope.
Physical Review Letters, 2006
Based on highly accurate laboratory measurements of Lyman bands of H 2 and an updated representation of the structure of the ground X 1 g and excited B 1 u and C 1 u states, a new set of sensitivity coefficients K i is derived for all lines in the H 2 spectrum, representing the dependence of their transition wavelengths on a possible variation of the proton-electron mass ratio m p =m e . Included are local perturbation effects between B and C levels and adiabatic corrections. The new wavelengths and K i factors are used to compare with a recent set of highly accurate H 2 spectral lines observed in the Q 0347-383 and Q 0405-443 quasars, yielding a fractional change in the mass ratio of = 2:4 0:6 10 ÿ5 for a weighted fit and = 2:0 0:6 10 ÿ5 for an unweighted fit. This result indicates, at a 3:5 confidence level, that could have decreased in the past 12 Gyr.
Keck telescope constraint on cosmological variation of the proton-to-electron mass ratio
Monthly Notices of the Royal Astronomical Society, 2010
Molecular transitions recently discovered at redshift z abs = 2.059 toward the bright background quasar J2123−0050 are analysed to limit cosmological variation in the proton-toelectron mass ratio, µ ≡ m p /m e . Observed with the Keck telescope, the optical echelle spectrum has the highest resolving power and largest number (86) of H 2 transitions in such analyses so far. Also, (seven) HD transitions are used for the first time to constrain µ-variation. These factors, and an analysis employing the fewest possible free parameters, strongly constrain µ's relative deviation from the current laboratory value: ∆µ/µ = (+5.6±5.5 stat ±2.9 sys )× 10 −6 , indicating an insignificantly larger µ in the absorber. This is the first Keck result to complement recent null constraints from three systems at z abs > 2.5 observed with the Very Large Telescope. The main possible systematic errors stem from wavelength calibration uncertainties. In particular, distortions in the wavelength solution on echelle order scales are estimated to contribute approximately half the total systematic error component, but our estimate is model dependent and may therefore under or overestimate the real effect, if present.
Monthly Notices of the Royal Astronomical Society, 2013
We present an accurate analysis of the H 2 absorption lines from the z abs ∼ 2.4018 damped Lyαsystem towards HE 0027−1836 observed with the Very Large Telescope Ultraviolet and Visual Echelle Spectrograph (VLT/UVES) as a part of the European Southern Observatory Large Programme "The UVES large programme for testing fundamental physics" to constrain the variation of proton-to-electron mass ratio, µ ≡ m p /m e . We perform cross-correlation analysis between 19 individual exposures taken over three years and the combined spectrum to check the wavelength calibration stability. We notice the presence of a possible wavelength dependent velocity drift especially in the data taken in 2012. We use available asteroids spectra taken with UVES close to our observations to confirm and quantify this effect. We consider single and two component Voigt profiles to model the observed H 2 absorption profiles. We use both linear regression analysis and Voigt profile fitting where ∆µ/µ is explicitly considered as an additional fitting parameter. The two component model is marginally favored by the statistical indicators and we get ∆µ/µ = −2.5 ± 8.1 stat ± 6.2 sys ppm. When we apply the correction to the wavelength dependent velocity drift we find ∆µ/µ = −7.6 ± 8.1 stat ± 6.3 sys ppm. It will be important to check the extent to which the velocity drift we notice in this study is present in UVES data used for previous ∆µ/µ measurements.
Physical Review Letters, 2011
A high signal-to-noise spectrum covering the largest number of hydrogen lines (90 H 2 lines and 6 HD lines) in a high redshift object was analyzed from an observation along the sight-line to the bright quasar source J2123−005 with the UVES spectrograph on the ESO Very Large Telescope (Paranal, Chile). This delivers a constraint on a possible variation of the proton-toelectron mass ratio of ∆µ/µ = (8.5 ± 3.6 stat ± 2.2 syst ) × 10 −6 at redshift z abs = 2.059, which agrees well with a recently published result on the same system observed at the Keck telescope yielding ∆µ/µ = (5.6 ± 5.5 stat ± 2.9 syst ) × 10 −6 . Both analyses used the same robust absorption line fitting procedures with detailed consideration of systematic errors. PACS numbers: 06.20.Jr, 95.85.Mt, 98.80.Es, 33.20.-t 1 arXiv:1104.2969v1 [astro-ph.CO]
Astronomy and Astrophysics, 2013
We present an accurate analysis of the H 2 absorption lines from the z abs ∼ 2.4018 damped Lyαsystem towards HE 0027−1836 observed with the Very Large Telescope Ultraviolet and Visual Echelle Spectrograph (VLT/UVES) as a part of the European Southern Observatory Large Programme "The UVES large programme for testing fundamental physics" to constrain the variation of proton-to-electron mass ratio, µ ≡ m p /m e . We perform cross-correlation analysis between 19 individual exposures taken over three years and the combined spectrum to check the wavelength calibration stability. We notice the presence of a possible wavelength dependent velocity drift especially in the data taken in 2012. We use available asteroids spectra taken with UVES close to our observations to confirm and quantify this effect. We consider single and two component Voigt profiles to model the observed H 2 absorption profiles. We use both linear regression analysis and Voigt profile fitting where ∆µ/µ is explicitly considered as an additional fitting parameter. The two component model is marginally favored by the statistical indicators and we get ∆µ/µ = −2.5 ± 8.1 stat ± 6.2 sys ppm. When we apply the correction to the wavelength dependent velocity drift we find ∆µ/µ = −7.6 ± 8.1 stat ± 6.3 sys ppm. It will be important to check the extent to which the velocity drift we notice in this study is present in UVES data used for previous ∆µ/µ measurements.