Water really is everywhere. Two teams of astronomers, each led by scientists at the California Institute of Technology (Caltech), have discovered the largest and farthest reservoir of water ever detected in the universe.

Looking from a distance of 30 billion trillion miles away into a quasar-one of the brightest and most violent objects in the cosmos-the researchers have found a mass of water vapor that's at least 140 trillion times that of all the water in the world's oceans combined, and 100,000 times more massive than the sun.

Because the quasar is so far away, its light has taken 12 billion years to reach Earth. The observations therefore reveal a time when the universe was just 1.6 billion years old. "The environment around this quasar is unique in that it's producing this huge mass of water," says Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory (JPL), and a visiting associate at Caltech.

"It's another demonstration that water is pervasive throughout the universe, even at the very earliest times." Bradford leads one of two international teams of astronomers that have described their quasar findings in separate papers that have been accepted for publication in the Astrophysical Journal Letters.

A quasar is powered by an enormous black hole that is steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.

Since astronomers expected water vapor to be present even in the early universe, the discovery of water is not itself a surprise, Bradford says. There's water vapor in the Milky Way, although the total amount is 4,000 times less massive than in the quasar, as most of the Milky Way's water is frozen in the form of ice.

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 (a light-year is about six trillion miles), and its presence indicates that the gas is unusually warm and dense by astronomical standards.

Although the gas is a chilly -53 degrees Celsius (-63 degrees Fahrenheit) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.

The water vapor is just one of many kinds of gas that surround the quasar, and its presence indicates that the quasar is bathing the gas in both X-rays and infrared radiation. The interaction between the radiation and water vapor reveals properties of the gas and how the quasar influences it. 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 feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or may be ejected from the quasar.

Bradford's team made their observations starting in 2008, using an instrument called Z-Spec at the Caltech Submillimeter Observatory (CSO), a 10-meter telescope near the summit of Mauna Kea in Hawaii. Z-Spec is an extremely sensitive spectrograph, requiring temperatures cooled to within 0.06 degrees Celsius above absolute zero. The instrument measures light in a region of the electromagnetic spectrum called the millimeter band, which lies between infrared and microwave wavelengths.

The researchers' discovery of water was possible only because Z-Spec's spectral coverage is 10 times larger than that of previous spectrometers operating at these wavelengths. The astronomers made follow-up observations with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.

This discovery highlights the benefits of observing in the millimeter and submillimeter wavelengths, the astronomers say.

The field has developed rapidly over the last two to three decades, and to reach the full potential of this line of research, the astronomers-including the study authors-are now designing CCAT, a 25-meter telescope to be built in the Atacama Desert in Chile. CCAT will allow astronomers to discover some of the earliest galaxies in the universe.

By measuring the presence of water and other important trace gases, astronomers can study the composition of these primordial galaxies.

The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the CSO, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team was looking for traces of hydrogen fluoride in the spectrum of APM 08279+5255, but serendipitously detected a signal in the quasar's spectrum that indicated the presence of water.

The signal was at a frequency corresponding to radiation that is emitted when water transitions from a higher energy state to a lower one. While Lis's team found just one signal at a single frequency, the wide bandwidth of Z-Spec enabled Bradford and his colleagues to discover water emission at many frequencies. These multiple water transitions allowed Bradford's team to determine the physical characteristics of the quasar's gas and the water's mass.

earlier related report
Farthest, largest water mass in universe found, says study involving Caltech, CU-Boulder
Boulder CO (SPX) Jul 25 - An international team of astronomers led by the California Institute of Technology and involving the University of Colorado Boulder has discovered the largest and farthest reservoir of water ever detected in the universe.

The distant quasar is one of the most powerful known objects in the universe and has an energy output of 1,000 trillion suns - about 65,000 times that of the Milky Way galaxy. The quasar's power comes from matter spiraling into the central supermassive black hole, estimated at some 20 billion times the mass of our sun, said study leader Matt Bradford of Caltech and NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Because the quasar - essentially a voraciously feeding black hole - is so far away, its light has taken 12 billion light years to arrive at Earth. Since one light year equals about 6 trillion miles, the observations reveal a time when the universe was very young, perhaps only 1.6 billion years old. Astronomers believe the universe was formed by the Big Bang roughly 13.6 billion years ago.

The water measured in the quasar is in the form of vapor and is the largest mass of water ever found, according to the researchers. The amount of water estimated to be in the quasar is at least 100,000 times the mass of the sun, equivalent to 34 billion times the mass of the Earth.

In an astronomical context, water is a trace gas, but it indicates gas that is unusually warm and dense, said Bradford. "In this case, the water measurement shows that the gas is under the influence of the growing black hole, bathed in both infrared and X-ray radiation," he said.

"These findings are very exciting," said CU-Boulder Associate Professor Jason Glenn, a study co-author. "We not only detected water in the farthest reaches of the universe, but enough to fill Earth's oceans more than 100 trillion times."

The water measurement, together with measurements of other molecules in the vapor source, suggests there is enough gas present for the black hole to grow to about six times its already massive size, said Bradford. Whether it will grow to this size is not clear, however, as some of the gas may end up forming stars instead, or be ejected from the quasar host galaxy in an outflow.

In the Milky Way, the mass of gaseous water is at least 4,000 times smaller than that in the quasar, in part because most of the water in our own galaxy is frozen into ice. While the water vapor in the Milky Way is found only in a limited number of regions, a few light years in size or smaller, the water in the distant quasar appears to be distributed over hundreds of light years, said the researchers.

The discovery was made with a spectrograph called Z-Spec operating in the millimeter wavelengths - found between the infrared and microwave wavelengths - at the Caltech Submillimeter Observatory, a 10-meter telescope near the summit of Mauna Kea, on the big island of Hawaii. Z-Spec's detectors are cooled to within 0.06 degrees Celsius of absolute zero in order to obtain the exquisite sensitivity required for these measurements.

"Breakthroughs are coming fast in millimeter and submillimeter technology, enabling us to study ancient galaxies caught in the act of forming stars and supermassive black holes," said CU-Boulder's Glenn, who is a co-principal investigator on the Z-Spec instrument development and a fellow at CU-Boulder's Center for Astrophysics and Space Astronomy. "The excellent sensitivity of Z-Spec and similar technology will allow astronomers to continue to make important and surprising findings related to distant celestial objects in the early universe, with implications for how our own Milky Way galaxy formed."

Confirmation for this important discovery came from images obtained by the Combined Array for Research in Millimeter-Wave Astronomy, or CARMA, a sensitive array of radio dishes located in the Inyo Mountains of Southern California. The distant quasar under study is named APM 08279+5255.

The discovery highlights the utility of the millimeter and submillimeter band for astronomy, which has developed rapidly in the last two to three decades. To achieve the potential of this relatively new spectral range, astronomers, including the study authors, are now designing CCAT, a 25-meter telescope for the high Chilean Atacama desert. With CCAT astronomers will discover some of the earliest galaxies in the universe, and will be able to study their gas content via measurements of water as well as other important gas species, Glenn said.

earlier related report
Astronomers Discover Universe's Largest and Earliest Mass of Water
College Park MD (SPX) Jul 25 - A team of astronomers has discovered the largest, oldest mass of water ever detected in the universe. The newly detected cloud of water vapor, equivalent to 140 trillion times the water in the world's oceans, is more than 12 billion light-years from Earth and surrounds a huge black hole, called a quasar.

"Because the light we are seeing left this quasar more than 12 billion years ago, we are seeing water that was present only some 1.6 billion years after the beginning of the Universe," said the University of Maryland astronomer Alberto Bolatto, coauthor of a new paper accepted to the Astrophysical Journal Letters. "This discovery pushes the detection of water 1 billion years closer to the Big Bang than any previous find."

"It's another demonstration that water is pervasive throughout the universe, even at the very earliest times," said Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory and a visiting faculty associate at the California Institute of Technology, both in Pasadena, Calif. Bradford leads the partially NASA-funded research, described in the paper.

Quasars are the most luminous, most powerful and most energetic objects in the universe. They are powered by enormous black holes that suck in surrounding gas and dust and spew out huge amounts of energy. Bradford, Bolatto and their colleagues studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.

Scientists think water vapor was present even in the early universe, so the discovery of water is not itself a surprise. Our own Milky Way has water vapor. However, because most of the Milky Way's water is in the form of ice, the amount of water vapor in our galaxy is 4,000 times less than the newly discovered water cloud around quasar APM 08279+5255.

This water vapor is an important trace gas that reveals much about the nature of this quasar. The water vapor is distributed around the massive 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, but only by astronomical standards. Its temperature is minus 63 degrees Fahrenheit (53 degrees Celsius), and the huge cloud of water is 300 trillion times less dense than Earth's atmosphere. Still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.

Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest that there is enough gas to feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or may be ejected from the quasar.

In much the same way that physicians use different screening and confirming tests to determine the presence of disease, the astronomers used two different instruments, "Z-Spec" and CARMA, to identify the presence of the oldest and most distant water yet discovered.

The spectral signature for water vapor was first detected using the "Z-Spec" instrument at the Caltech Submillimeter Observatory, a 10-meter telescope near the summit of Mauna Kea in Hawaii. The instrument measures light in a region of the electromagnetic spectrum called the millimeter band, which lies between infrared and microwave wavelengths. The researchers were able to detect the possible presence of water around this quasar only because Z-Spec's spectral coverage is ten times larger than those of previous spectrometers operating at these wavelengths.

However, to confirm that what they had found really was water, a different instrument was needed, the Combined Array for Research in Millimeter-Wave Astronomy (CARMA). CARMA is a linked array of 15 radio telescope dishes perched high in the cool, dry desert of eastern California's Inyo Mountains.

The other authors on Lis's paper, "Discovery of water vapor in the high-redshift quasar APM 08279+5255 at Z=3.91," are Tom Phillips, Caltech's John D. MacArthur Professor of Physics and director of the CSO; David Neufeld of Johns Hopkins University; Maryvonne Gerin of the Paris Observatory and the French National Center for Scientific Research; and Roberto Neri of the Institute of Millimeter Radio Astronomy in France. Funding was provided by the National Science Foundation (NSF).

The authors on Bradford's paper, "The water vapor spectrum of APM 08279+5255: X-ray heating and infrared pumping over hundreds of parsecs," include Caltech's Hien Nguyen, a visiting associate and lecturer in physics; Jamie Bock, senior faculty associate in physics and scientist at JPL; and Jonas Zmuidzinas, the Merle Kingsley Professor of Physics and chief technologist at JPL. The other authors are Alberto Bolatto of the University of Maryland, College Park; Philip Maloney, Jason Glenn, and Julia Kamenetzky of the University of Colorado, Boulder; James Aguirre, Roxana Lupu, and Kimberly Scott of the University of Pennsylvania; Hideo Matsuhara of the Institute of Space and Astronautical Science in Japan; Eric Murphy of the Carnegie Institution for Science; and Bret Naylor of JPL.

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