Radio Waves Can Probe The Centers Of Violent Galaxies

Radio astronomers have pioneered systems for interferometry. This technique combines the signals from several instruments in a manner that allows them to act as a single "virtual telescope," one with a huge effective diameter equaling the distance between the most widely separated telescopes. The greater the diameter of a telescope, the more detail it can see. An example is the Very Large Array (VLA) of movable radio telescopes near Socorro, New Mexico, with an effective diameter of up to 27 kilometers. Building on the VLA's success, the Expanded Very Large Array (EVLA) will create an array of radio dishes with 10 times the VLA's sensitivity and angular resolution. The EVLA will have a thousand times the VLA's capability for making spectroscopic observations at different radio wavelengths. The expansion will involve replacement of the current detectors,computers, and software to improve sensitivity. In a second stage of the expansion, as many as eight new antennas will be built. Interconnected by fiber-optic links, the new and old dishes will allow the EVLA to study the cosmos with an angular resolution comparable to that of the Next Generation Space Telescope (NGST) and of the Atacama Large Millimeter Array (ALMA). These three instruments will complement one another by providing high-resolution views of the cosmos in the spectral domains of radio, millimeter (radio waves with the shortest wavelengths), and infrared wavelengths.

Still finer angular resolution will come from the Advanced Radio Inter-ferometry between Space and Earth (ARISE) initiative. ARISE combines a radio telescope 25 meters in diameter, orbiting in space, with the existing Very Long Baseline Array (VLBA) of radio telescopes. ARISE will enable the study of explosive events, such as the jets ejected from the matter orbiting a supermassive black hole. It will have a precision that may be good enough to explain how and why these ejections occur. And it may be able to reveal how the ejection of matter leads to the production of an enormous quantity of radio emissions. But a system with even the finest angular resolution cannot observe faint sources unless it can collect sufficient amounts of radiation. To observe the faintest radio sources in the cosmos, radio astronomers from around the world are planning the Square Kilometer Array (SKA) of radio telescopes, which will cover a total area of one square kilometer. The SKA will have hardware and software capable of simultaneously analyzing the signals detected in each of the huge number of telescopes in the array. The SKA will effectively function as a single radio dish even larger than 1 kilometer in diameter, possessing 10 times the collecting area of the 300-meter radio telescope near Arecibo, Puerto Rico. The SKA will be able to observe the clouds of gas that formed the precursors of galaxies 12 to 14 billion years ago, as well as gas within distant galaxies. The Astronomy and Astrophysics Survey Committee recommends that, during this decade, resources be provided for the U.S. contribution to the technology development required for the SKA, which will be by far the most sensitive radio instrument ever built.

Visit the Official EVLA Site

Visit the Official ARISE Site

Back To What Happens At The Heart Of A Galaxy

Back to Text Home