Searching for chameleon-like scalar fields with the ammonia method

Levshakov, S. A.; Lapinov, A. V.; Henkel, C.; Molaro, P.; Reimers, D.; Kozlov, M. G.; Agafonova, I. I.

doi:10.1051/0004-6361/201015332

Cited by 51 publications

(49 citation statements)

References 59 publications

(64 reference statements)

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“…The observed velocity differences are evenly distributed about the mean (median -2 ms −1 ). The gas number density (n H2 ) in the regions where the methanol masers arise are around 10 6 -10 7 cm −3 , hence the limitations on chameleon-like scalar fields implied by these observations are comparable to those obtained from previous observations of NH 3 and HC 3 N [18].…”

supporting

confidence: 77%

Practical Limitations on Astrophysical Observations of Methanol to Investigate Variations in the Proton-to-Electron Mass Ratio

2011

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The possibility of using astrophysical observations of rotational transitions in the methanol molecule to measure, or constrain temporal and spatial variations in the proton-to-electron mass ratio (µ) has recently been investigated by several groups. Here we outline some of the practical considerations of making such observations, including both the instrumental and astrophysical limitations which exist at present. This leads us to conclude that such observations are unlikely to be able to improve evidence either for, or against the presence of variations in the proton-to-electron mass ratio by more than an order of magnitude beyond current limits.PACS numbers: 06.20. Jr, 98.38.Er, 98.58.Ec The possibility of using astrophysical observations of rotational transitions in the methanol molecule to measure, or constrain temporal and spatial variations in the proton-to-electron mass ratio (µ) has recently been suggested by several groups [1,2]. The first attempts to use astronomical observations of methanol masers to constrain µ within the Milky Way show that |∆µ/µ| < 28 × 10 −9 [2].The hindered internal rotation exhibited by methanol produces the degeneracy which makes the different rotational transitions particularly sensitive to the protonto-electron mass ratio [1]. It also leads to the rich rotational and vibrational spectrum, which due to quantum mechanical selection rules produces a large number of centimetre and millimetre maser transitions in interstellar space. The strongest and most common of these is the 5 1 → 6 0 A + transition which has a rest frequency of approximately 6.7 GHz. It has been detected towards more than 900 sites of high-mass star formation in the Milky Way [see for example 3, 4]. The second strongest astrophysical transition of methanol is from the 2 0 → 3 −1 E transition which has a rest frequency of approximately 12.2 GHz, and is observed towards 43% of those sources showing 6.7 GHz emission [5]. In most methanol maser regions multiple spectral features are observed in the spectra of 6.7 or 12.2 GHz methanol masers at different Doppler shifted velocities [3,4]. The spectral features typically have near-Gaussian profiles (although spectral blending between spatially unresolved components affects most observations), and FWHM (full-width half maximum) of a few tenths of kilometers per second.The K µ coefficient measures the sensitivity of a transition to the proton-to-electron mass ratio and for the 6.7 and 12.2 GHz methanol transitions these have been calculated to be -42 and -33 respectively [1]. To improve constraints on |∆µ/µ|, beyond those already achieved [2], requires measurement of the relative Doppler shifted velocities of the different transitions to an accuracy of better than 100 ms −1 . When the 6.7 and 12.2 GHz methanol transitions exhibit peaks at the same velocity they have been demonstrated to arise from the same locations at the milliarcsecond level (corresponding to linear scales of a few AU at distances of a few kpc) [6,7]. The large number of 6.7 and 12.2 GHz methanol...

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confidence: 77%

Practical Limitations on Astrophysical Observations of Methanol to Investigate Variations in the Proton-to-Electron Mass Ratio

2011

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“…For comparison, in the Milky Way the [C i]/CO pairs restrict ΔF/F at the level of |ΔF/F| < 0.4 ppm (Levshakov et al 2010a) leading to a limit on |Δα/α| < 0.2 ppm since the spatial variations in μ are restricted to |Δμ/μ| < 0.03 ppm in the disk of the Milky Way (Levshakov et al 2010b;Levshakov et al 2010c;Levshakov et al 2011;Ellingsen et al 2011).…”

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confidence: 99%

An upper limit to the variation in the fundamental constants at redshiftz= 5.2

Levshakov

Combes

Boone

et al. 2012

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Aims. We constrain a hypothetical variation in the fundamental physical constants over the course of cosmic time. Methods. We use unique observations of the CO(7-6) rotational line and the [C i] 3 P 2 − 3 P 1 fine-structure line towards a lensed galaxy at redshift z = 5.2 to constrain temporal variations in the constant F = α 2 /μ, where μ is the electron-to-proton mass ratio and α is the fine-structure constant. The relative change in F between z = 0 and z = 5.2, ΔF/F = (F obs − F lab )/F lab , is estimated from the radial velocity offset, ΔV = V rot − V fs , between the rotational transitions in carbon monoxide and the fine-structure transition in atomic carbon. Results. We find a conservative value ΔV = (1±5) km s −1 (1σ C.L.), which when interpreted in terms of ΔF/F gives ΔF/F < 2×10 −5 . Independent methods restrict the μ-variations at the level of Δμ/μ < 1 × 10 −7 at z = 0.7 (look-back time t z0.7 = 6.4 Gyr). Assuming that temporal variations in μ, if any, are linear, this leads to an upper limit on Δμ/μ < 2 × 10 −7 at z = 5.2 (t z5.2 = 12.9 Gyr). From both constraints on ΔF/F and Δμ/μ , one obtains for the relative change in α the estimate Δα/α < 8 × 10 −6 , which is at present the tightest limit on Δα/α at early cosmological epochs.

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“…Two major directions of search for variation in α and in β are observational studies, such as analysis of high resolution spectroscopy from dark clouds in interstellar space (see, e.g., Ref. [4][5][6][7][8][9] and references therein), and laboratory research, including frequency comparison of optical and microwave atomic clocks over extended periods of time (see, e.g., [6,7,[10][11][12][13]). …”

Section: Introductionmentioning

confidence: 99%

Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

et al. 2011

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We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine structure constant α. The method used follows ideas Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron to proton mass ratio, β, was considered. We demonstrate that for heavy systems, the sensitivity to variation of α is of the same order of magnitude as to variation of β. Near narrow Feshbach resonances the enhancement of the sensitivity may exceed nine orders of magnitude.

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Searching for chameleon-like scalar fields with the ammonia method

Cited by 51 publications

References 59 publications

Practical Limitations on Astrophysical Observations of Methanol to Investigate Variations in the Proton-to-Electron Mass Ratio

Practical Limitations on Astrophysical Observations of Methanol to Investigate Variations in the Proton-to-Electron Mass Ratio

An upper limit to the variation in the fundamental constants at redshiftz= 5.2

Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

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