Abstract
HeHHe is the only potential molecule comprised of atoms present in the early universe that is also easily observable in the infrared. This molecule has been known to exist in mass spectrometry experiments for nearly half-a-century and is likely present, but as-of-yet unconfirmed, in cold plasmas. There can exist only a handful of plausible primordial molecules in the epochs before metals (elements with nuclei heavier than He as astronomers call them) were synthesized in the universe, and most of these are both rotationally and vibrationally dark. The current work brings HeHHe into the discussion as a possible (and potentially only) molecular candle for probing high-z and any metal-deprived regions due to its exceptionally bright infrared feature previously predicted to lie at 7.43 m. Furthermore, the present study provides new insights into its possible formation mechanisms as well as marked stability, along with the decisive role of anharmonic zero-point energies. A new entrance pathway is proposed through the triplet state () of the HeH molecule complexed with a hydrogen atom and a subsequent 10.90 eV charge transfer/photon emission into the linear and vibrationally-bright HeHHe form.
Highlights
Atomic and molecular spectroscopic signatures are the fingerprints of the universe
While there are a surprising number of possible hydro-helium species [11,13,14], none are as tantalizing as the triatomic molecule, HeHHe+
The present work shows that several bound states have been missed for this molecule and could play an important role in its formation or persistence in the metal-deprived universe
Summary
Atomic and molecular spectroscopic signatures are the fingerprints of the universe. In the era before metals (metals in the astrophysical acceptance are atoms built with nuclei heavier than 4 He), only 1 H and 4 He, with a trace amount of lithium (along with 2 H and 3 He), comprised the matter of the universe. While there are a surprising number of possible hydro-helium species [11,13,14], none are as tantalizing as the triatomic molecule, HeHHe+ Even if this molecule has no permanent dipole moment precluding any rotational observation, it has recently been shown quantum chemically to possess an exceptionally bright vibrational frequency (the antisymmetric stretch) at. Since the HeHHe+ molecule possesses a very large transition dipole in the IR, its role in the cooling of metal-poor gases cannot be neglected off-handedly and such an intense molecular radiator is of crucial importance to model the few ingredients that will constrain the initial mass function of the population
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have