Pasadena, CA— Water really is everywhere. A team of astronomers have found the largest and farthest reservoir of water ever detected in the universe—discovered in the central regions of a distant quasar. Quasars contain massive black holes that are steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out huge amounts of energy. The energy from this particular quasar was released some 12 billion years ago, only 1.6 billion years after the Big Bang and long before most of the stars in the disk of our Milky Way galaxy began forming.

The research team includes Carnegie’s Eric Murphy, as well as scientists from the Jet Propulsion Laboratory, the California Institute of Technology, University of Maryland, University of Colorado, University of Pennsylvania, and the Institute for Space and Astronautical Science in Japan. Their research will be published in Astrophysical Journal Letters.

The quasar’s newly discovered mass of water exists in gas, or vapor, form. It is estimated to be at least 100,000 times the mass of the Sun, equivalent to 34 billion times the mass of the Earth or 140 trillion times the mass of water in all of Earth’s oceans put together.

Since astronomers expected water vapor to be present even in the early universe, the discovery of water is not itself a surprise. There is water vapor in the Milky Way, although the amount is 4,000 times less massive than in the quasar. There is other water in the Milky Way, but it is frozen and not vaporous.

Nevertheless water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light years in size (a light year is about six trillion miles). The gas is unusually warm and dense by astronomical standards. It is five-times hotter and 10- to 100-times denser than what is typical in galaxies like the Milky Way.

The large quantity of water vapor in the quasar indicates that it is bathing the gas in both X-rays and infrared radiation. The interaction between the radiation and water vapor reveals properties of how the gas is influenced by the quasar. For example, analyzing the water vapor shows how the radiation heats the rest of the gas. Furthermore, measurements of the water vapor and of other molecules, such as carbon monoxide, suggest that there is enough gas to enable the black hole to grow to about six times its size. Whether or not this has happened is unclear, the astronomers say, since some of the gas could condense into stars or being ejected from the quasar.

A major new telescope in the design phase called CCAT will allow astronomers to measure the abundance of water vapor in many of the early Universe’s galaxies.

Funding for Z-Spec was provided by NSF, NASA, the Research Corporation, and the partner institutions. The Caltech Submillimiter Observatory is operated by the California Institute of Technology under a contract from the NSF. CARMA was built and is operated by a consortium of universities—The California Institute of Technology, University of California Berkeley, University of Maryland College Park, University of Illinois Urbana-Champaign, and the University of Chicago—with funding from a combination of state and private sources, as well as the NSF and its University Radio Observatory program.


Caption: Image of a distant quasar courtesy of NASA Goddard Space Flight Center.

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