HD as a probe for detecting mass variation on a cosmological time scale

Area of Science:

• Cosmology
• Astrophysics
• Quantum Chemistry
• Spectroscopy

Background:

• The B1 Sigma u+-X1 Sigma g+ Lyman and C1Pi u-X1 Sigma g+ Werner bands of H2 and HD are sensitive to fundamental physical constants.
• Previous studies have explored mass-variation effects using molecular spectroscopy, but high-precision data for HD at high redshift is crucial.

Purpose of the Study:

• To precisely measure prominent HD lines in the extreme ultraviolet (EUV) spectrum.
• To determine sensitivity coefficients for HD lines with respect to the proton-electron mass ratio (mu).
• To establish a database for comparing laboratory and astrophysical data to probe cosmological mass-variation effects.

Main Methods:

• High-resolution laboratory spectroscopy of HD lines in the EUV.
• Quantum ab initio calculations to determine sensitivity coefficients (Ki).
• Analysis of spectral data to probe mass-variation effects on cosmological timescales.

Main Results:

• High-accuracy laboratory determination of prominent HD lines with delta lambda/lambda approximately 5 x 10(-8).
• Determination of sensitivity coefficients Ki = d ln lambda i/d ln mu for HD as a function of mu.
• Creation of a database for comparison with high-redshift astrophysical observations.

Conclusions:

• The precise laboratory data and calculated sensitivity coefficients for HD provide a robust tool for probing mass-variation effects.
• This research contributes to setting stringent limits on the variation of fundamental constants over cosmological time.
• Strategies for detecting effects beyond first-order mass ratio deviations are discussed.