Two teams of astronomers have made an incredible discovery: the largest and most distant reservoir of water ever found in the universe. This enormous amount of water, equivalent to 140 trillion times the volume of Earth’s oceans, surrounds a massive black hole known as a quasar, located over 12 billion light-years away.
“This quasar’s environment is highly unique as it contains an immense amount of water,” stated Matt Bradford, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This finding further emphasizes the widespread presence of water throughout the universe, even during its earliest stages.” Bradford leads one of the research teams involved in this discovery, and their work, partially funded by NASA, is published in the Astrophysical Journal Letters.
A quasar is fueled by an enormous black hole that consumes a surrounding disk of gas and dust. As it devours matter, the quasar emits immense amounts of energy. Both groups of astronomers focused on studying a specific quasar known as APM 08279+5255, which hosts a black hole 20 billion times more massive than the sun and releases energy equivalent to that of a thousand trillion suns.
While scientists expected water vapor to exist in the early universe, they had not previously detected it at such extreme distances. Water vapor is present in the Milky Way, although in significantly lesser amounts, approximately 4,000 times less than in the quasar, mainly due to the majority of the Milky Way’s water being frozen as ice.
Water vapor serves as a crucial indicator of the quasar’s nature. In this particular quasar, the water vapor is distributed in a gaseous region surrounding the black hole, spanning hundreds of light-years (a light-year equals about six trillion miles). Its presence suggests that the quasar is enveloping the gas in X-rays and infrared radiation, resulting in the gas being exceptionally warm and dense in astronomical terms. Although the gas remains frigid at minus 63 degrees Fahrenheit (minus 53 degrees Celsius) and is 300 trillion times less dense than Earth’s atmosphere, it still possesses a temperature five times hotter and a density 10 to 100 times greater than what is typically observed in galaxies like the Milky Way.
Analysis of the water vapor, along with other molecules like carbon monoxide, indicates that there is sufficient gas to sustain the black hole’s growth until it becomes approximately six times larger. However, the astronomers note that it is unclear whether this growth will occur, as some of the gas might condense into stars or be ejected from the quasar.
Bradford’s team conducted their observations beginning in 2008 using the “Z-Spec” instrument at the California Institute of Technology’s Submillimeter Observatory, a 33-foot (10-meter) telescope situated near the summit of Mauna Kea in Hawaii. Follow-up observations were conducted using the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes located in the Inyo Mountains of Southern California.
The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, employed the Plateau de Bure Interferometer in the French Alps to detect the presence of water. In 2010, Lis’s team serendipitously identified water in APM 8279+5255, observing a single spectral signature. Bradford’s team, on the other hand, obtained more comprehensive information about the water, including its tremendous mass, as they detected multiple spectral signatures of the water.
