English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Methanol is an important tracer to probe physical and chemical conditions inthe interstellar medium of galaxies. Methanol is also the most sensitive targetmolecule for probing potential space-time variations of the proton-electronmass ratio, mu, a dimensionless constant of nature. We present an extensiveALMA study of the strongest submillimeter absorption lines of methanol [...] inthe z=0.89 molecular absorber toward PKS1830-211, the only high-redshift objectin which methanol has been detected. Our goals are to constrain the excitationof the methanol lines and to investigate the cosmological invariance of mubased on their relative kinematics. [...] We explore methanol excitation byrunning the non local thermal equilibrium radiative transfer code RADEX [...]The excitation analysis points to a cool (~10-20 K) and dense (~10^{4-5} cm-3)methanol gas. [...] In addition, we measure an abundance ratio A/E = 1.0 +/-0.1, an abundance ratio CH3OH/H2 ~ 2 x 10^{-8}, and a 12CH3OH/13CH3OH ratio 62+/- 3. Our analysis shows that the bulk velocities of the different transitionsare primarily correlated with the observing epoch due to morphological changesin the background quasar's emission. There is a weaker correlation between bulkvelocities and the lower level energies of the transitions, which could be asignature of temperature-velocity gradients in the absorbing gas. As a result,we do not find evidence for variations of mu, and we estimate Dmu/mu = (-1.8+/- 1.2) x 10^{-7} at 1sigma from our multivariate linear regression. We set arobust upper limit | \Dmu/mu | < 3.6 x 10^{-7} (3sigma) for the invariance ofmu at a look-back time of half the present age of the Universe. Our analysishighlights that systematics need to be carefully taken into account in futureradio molecular absorption studies aimed at testing Dmu/mu below the 10^{-7}horizon. (Abridged)

A study of submillimeter methanol absorption toward PKS1830-211: Excitation, invariance of the proton-electron mass ratio, and systematics