Category Archives: quasars

astronomy, gravitational lenses, masers, quasars, water

Water, Water Everywhere… and When

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Even 11.1 Billion Years Ago

Water appears to be ubiquitous throughout the universe. Which is to say that astronomers spot traces of water vapor in various parts of the universe like other planets, moons, and throughout our galaxy. But, often enough, astronomers find H2O vapor in water masers. These are beamed radiation sources that are similar to lasers, but radiate at microwave wavelengths. These masers are often found in regions where hot, dense dust and gas are coalescing — like galaxy cores and starbirth regions.

So, astronomers have wondered how early in the universe water vapor might have existed. Another way to ask that question is to wonder how far away the most distant water vapor could be “seen” by our telescopes?  Water masers showing vapor have been found in galaxies close to ours, of course. But, what about more distant onces?

The quad gravitational lens MG J0414 + 0534, courtesy of VLBI.
The quad gravitational lens MG J0414 + 0534, courtesy of the extended Very Large Baseline Interferometer radio array (eVLBI).

The most recent answer came from data taken with the Effelsberg 100-meter radio telescope in Germany (operated by the Max Planck Institut for Radio Astronomy). Graduate student Violette Impellizzeri used the telescope to study the quasar MG J0414 +0534, which lies about 11.1 billion light-years away from us. We see it here in radio wavelengths that have been gravitationally lensed by an intervening galaxy (that is, the wavelengths of radiation and light from the more distant quasar are being bent by the gravitational influence of a massive galaxy that lies between us and the quasar).

The signature of water vapor was spotted in the radio data taken by Impellizzeri. It probably exists in clouds of dust and gas that feed a supermassive black hole at the center of the quasar. The detection of the water was later confirmed by observations made with the Expanded Very Large Array.

Make no mistake about it, this is a discovery of water in the very early universe — at a time when the universe was a fifth of its current age. It means that water may have been much more abundant in those early times. Because water masers are active close to galaxy cores, these masers may tell us something about the evolution of black holes and galaxy cores back at a time in the universe’s early history when galaxies were first forming.  I don’t know about you, but I find it fascinating just how something we take so much for granted (and is so commonplace) as water can help us get a look at the earliest epochs of cosmic history.

If you’re interested in reading more about this research, there’s a paper coming out in the December 18, 2009 issue of Nature magazine. Here’s the citation:

A gravitationally lensed water maser in the early Universe, C.M. Violette Impellizzeri, John P. McKean, Paola Castangia, Alan L. Roy, Christian Henkel, Andreas Brunthaler, & Olaf Wucknitz, 2008, Nature (18 December issue)
quasars

Feeding a Black Hole at the Center of a Quasar

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Artists conception of a quasar
Artist's conception of a quasar

Chances are if you’re interested in astronomy you’ve heard the terms quasars and black holes. They’re not exactly the same things, but it turns out that in many places in space, quasars and black holes are locked together in a cosmic dance. Quasars are bright objects that can outshine a trillion suns. Scientists think that quasasrs are the extremely luminous cores of galaxies. However, buried deep within those cores are dark secrets: black holes. These powerful and hidden objects have gravitational pulls so intense that nothing — not even light — can escape them. It may seem ironic but black holes are very likely the power sources for quasars.

How can this be?

The picture above is an artist’s concept by Aurore Simonnet of Sonoma State University of a black hole powering a quasar called QSO I Zw 1. In this image, the black hole is buried in the center of a disk of gas and dust (brown and yellow cloudy area in center). Scientists have discovered a cold ring of gas around a supermassive black hole at the center of the galaxy that makes up the quasar. To make QSO I Zw 1 shine with the brilliance of a trillion suns, it has to have a black hole with the mass of millions to billions of suns feeding on gas at the core of the galaxy.

Here’s how it works: the black hole pulls in material (gas, dust, stars) from the surrounding region of space. The material whirls around the black hole before swirling in like water down a drain. All this activity generates intense friction, which heats the gas and causes it to shine brightly. Although nothing can escape the crushing gravity of a black hole once past its boundary (called the event horizon), matter sometimes escapes after approaching — but not crossing — the event horizon. The material flies out in high-speed jets of gas that are often ejected near the poles of the black hole. Astronomers are still working to understand exactly how this works. The jets are represented in this image by yellow lines emanating from the center of the gas disk where the black hole is lurking.

Astronomers continue to study this very interesting galaxy as it interacts with a close galactic neighbor. The result of a close brush between galaxies is often a burst of star birth activity — and scientists want to know if it might also spur quasar activity as well.