WALLABY: A Radio Telescope

Source: The Hindu

Context:

A radio telescope in remote Western Australia is helping to build a 3-dimensional map of the night sky, mapping nearby galaxies up to a billion light years away.

About:

About WALLABY:

• WALLABY is a radio telescope in Western Australia that is helping astronomers build a three-dimensional map of the night sky.
• The WidefieldASKAP L-band Legacy All-sky Blind survey (or WALLABY) is one of two key surveys that are now running on the Australian SKA Pathfinder (ASKAP).
• It is an innovative imaging radio telescope located in an extremely radio-quiet zone (the Murchison Radio-astronomy Observatory) in Western Australia.

Aim of WALLABY:

To observe three-quarters of the whole sky in the 21-cm line of neutral hydrogen (or HI) at 30-arcsec resolution.

thereby detecting and imaging the gas distribution in hundreds of thousands of external galaxies in the local Universe.

The Hydrogen 21-cm Line:

The hydrogen in our galaxy has been mapped by the observation of the 21-cm wavelength line of hydrogen gas.

At 1420 MHz, this radiation from hydrogen penetrates the dust clouds and gives us a more complete map of the hydrogen than that of the stars themselves since their visible light won't penetrate the dust clouds.

It will help the researchers to measure:

1. measure the dark-matter distribution
2. the internal motion of galaxies
3. how these systems evolve and interact

What is radio astronomy and how is it used?

The radio telescope is, an astronomical instrument consisting of a radio receiver and an antenna system that is used to detect radio-frequency radiation between wavelengths of about 10 meters (30 megahertz [MHz]) and 1 mm (300 gigahertz [GHz]) emitted by extraterrestrial sources, such as stars, galaxies, and quasars.

Unlike optical telescopes, radio telescopes can detect invisible gas and, therefore, can reveal areas of space that may be obscured by cosmic dust.

Cosmic dust consists of tiny particles of solid material floating around in the space between the stars.

In its simplest form a radio telescope has three basic components:

• One or more antennas pointed to the sky, to collect the radio waves
• A receiver and amplifier to boost the very weak radio signal to a measurable level, and
• A recorder to keep a record of the signal.