Testing the variability of the proton-to-electron mass ratio from observations of methanol in the dark cloud core L1498

Abstract

The dependence of the proton-to-electron mass ratio, mu, on the local matter density was investigated using methanol emission in the dense dark cloud core L1498. Towards two different positions in L1498, five methanol transitions were detected and an extra line was tentatively detected at a lower confidence level in one of the positions. The observed centroid frequencies were then compared with their rest frame frequencies derived from least-squares fitting to a large data set. Systematic effects, as the underlying methanol hyperfine structure and the Doppler tracking of the telescope, were investigated and their effects were included in the total error budget. The comparison between the observations and the rest frame frequencies constrains potential mu variation at the level of Dmu/mu < 6 x 10^(-8), at a 3 sigma confidence level. For the dark cloud we determine a total CH3OH (A+E) beam averaged column density of 3-4 x 10^(12) cm(-2) (within roughly a factor of two), an E- to A-type methanol column density ratio of N(A-CH3OH)/N(E-CH3OH) = 1.00 +/- 0.15, a density of n(H2) = 3 x 10^5 cm^(-3) (again within a factor of two), and a kinetic temperature of Tkin = 6 +/- 1 K. In a kinetic model including the line intensities observed for the methanol lines, the n(H2) density is higher and the temperature is lower than that derived in previous studies based on different molecular species; the intensity of the 1_0 --> 1_-1 E line strength is not well reproduced.

arXiv comment10 pages, 6 figures, accepted for publication in MNRAS

References in corpus (29)

• A computer program for fast non-LTE analysis of interstellar line spectra
• Chameleon Fields: Awaiting Surprises for Tests of Gravity in Space
• An atomic and molecular database for analysis of submillimetre line observations
• A Search for Time Variation of the Fine Structure Constant
• Varying constants, Gravitation and Cosmology
• Systematic Molecular Differentiation in Starless Cores
• Detecting Dark Energy in Orbit -- the Cosmological Chameleon
• Environmental Dependence of Masses and Coupling Constants
• A Simple Varying-alpha Cosmology
• Space-Time Variation of Physical Constants and Relativistic Corrections in Atoms
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe
• Enhanced sensitivity to time-variation of m_p/m_e in the inversion spectrum of ammonia
• Accurate rest frequencies of methanol maser and dark cloud lines
• Constraining changes in the proton-electron mass ratio with inversion and rotational lines
• Robust Constraint on a Drifting Proton-to-Electron Mass Ratio at z=0.89 from Methanol Observation at Three Radio Telescopes
• The density, the cosmic microwave background, and the proton-to-electron mass ratio in a cloud at redshift 0.9
• Methanol as a tracer of fundamental constants
• Perspective: Tipping the scales - search for drifting constants from molecular spectra
• Limits on the dependence of the fine-structure constant on gravitational potential from white-dwarf spectra
• The UVES Large Program for testing fundamental physics - III. Constraints on the fine-structure constant from 3 telescopes
• Searching for chameleon-like scalar fields with the ammonia method
• Constraints on changes in the proton-electron mass ratio using methanol lines
• Search for a drifting proton--electron mass ratio from H${}_2$
• Searching for chameleon-like scalar fields with the ammonia method. II. Mapping of cold molecular cores in NH3 and HC3N lines
• Anthropic Reasons for Non-Zero Flatness and Lambda
• Limits on a Gravitational Field Dependence of the Proton--Electron Mass Ratio from H${}_2$ in White Dwarf Stars
• Limits on the spatial variations of the electron-to-proton mass ratio in the Galactic plane
• An Environmental Variation of Constants

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• Probing the electron-to-proton mass ratio gradient in the Milky Way with class I methanol masers
• Anomalous phosphine sensitivity coefficients as probes for a possible variation of the proton-to-electron mass ratio
• Optically Derived Radio-Frequency Benchmark in Methanol: A Sub-kHz Reference for Astrophysical Tests of Fundamental Physics
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