Water in the Early Universe

SH17_earlyWater.pngSPT0311-58 is the most massive infrared luminous system discovered so far during the Epoch of Reionization (EoR). In this paper, the authors present a detailed analysis of the molecular interstellar medium at z = 6.9, through high resolution observations of the CO(6 − 5), CO(7 − 6), CO(10 − 9), [CI](2 − 1), and p-H2O(21,1 − 20,2) lines and dust continuum emission with the Atacama Large Millimeter/submillimeter Array (ALMA). The system consists of a pair of intensely star-forming gravitationally lensed galaxies (labelled West and East). The intrinsic far-infrared luminosity is (16 ± 4)×1012 L⊙ in West and (27 ± 4)×1011 L⊙ in East. The authors model the dust, CO, and [CI] using non-local thermodynamic equilibrium radiative transfer models and estimate the intrinsic gas mass to be (5.4 ± 3.4)×1011 M⊙ in West and (3.1 ± 2.7)×1010 M⊙ in East. They find that the CO spectral line energy distribution in West and East are typical of high-redshift sub-millimeter galaxies (SMGs). The CO-to-H2 conversion factor (αCO) and the gas depletion time scales estimated from the model are consistent with the high-redshift SMGs in the literature within the uncertainties. They find no evidence of evolution of depletion time with redshift in SMGs at z > 3. This is the most detailed study of molecular gas content of a galaxy in the EoR to-date, with the most distant detection of H2O in a galaxy without any evidence for active galactic nuclei in the literature.

Image Caption: Composite showing the H2O, CO, and dust emission from a merging galaxy at z = 6.9.

Publication: Sreevani Jarugula (University of Illinois) et al., Molecular Line Observations in Two Dusty Star-Forming Galaxies at z = 6.9, Astrophysical Journal (accepted), arXiV:2108.11319.

NRAO Press Release: ALMA Scientists Detect Signs of Water in a Galaxy Far, Far Away

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.