PUNE: Scientists will now be able to find accurate positions of neutron stars in the galaxy, which will go a long way in discovering the existence of gravitational waves, helpful in tracing the evolution of the universe and the existence of extreme events like merging of two super-massive black-holes. City-based National Centre for Radio Astrophysics (NCRA), through its Giant Metrewave Radio Telescope (GMRT), has developed a novel technique of “gated imaging” to find the location of neutron stars or pulsars in the galaxy. The breakthrough technique gives scientists immediate knowledge of the positions of these stars and is said to be a thousand times more accurate and faster than the traditional technique.
Scientists here have also discovered five new pulsars in the galaxy and have applied the technique to identify their location.
NCRA scientists Jayanta Roy and Bhaswati Bhattacharya, who were
involved in the development of gated-imaging, claimed that this was the first time that such a technique had been created.
Expanding on the significance of the invention, Roy said, “The radio signal from a pulsar can only be observed when its beam of emission is pointing towards the earth, much like the way a lighthouse can only be seen when the light is pointed in the direction of an observer, thus giving a pulsed appearance. Once a new radio pulsar has been discovered, the traditional method for precise identification of its location in the sky requires a long series of observations spanning over a year or more.”
To make matters worse, Roy added, the pulses scatter when they travel through the ionised medium of the milky-way galaxy, so much so that a pulsar can no longer be detectable.
“To address this shortcoming, we have developed the new technique of “gated imaging” for millisecond pulsars, done when the pulsar beam is pointed towards us (pulsar ON) and away from us (pulsar OFF). By taking the difference of these two images, the precise identification and localisation of the pulsar is possible from a single set of observations, to an accuracy which is 1000 times better than that of the traditional technique,” Bhattacharya said.
Roy stressed that such immediate and accurate knowledge will quicken the follow-up study of millisecond pulsars aimed to uncover their properties. “The accurate position of these stars will also help scientists gauge their suitability for use in the “International Pulsar Timing” array, which is designed to detect gravitational wave signals in the universe,” he said.
The extension of these techniques to large radio telescopes like the Square Kilometre Array (SKA), currently being developed in Australia and South Africa, is also on cards.
The discovery of this imaging technique and the precise localisation of five newly-discovered millisecond pulsars with the GMRT were published in the Astrophysical Journal Letters in March this year.
Source : http://timesofindia.indiatimes.com/city/pune/National-Centre-for-Radio-Astrophysicss-breakthrough-discovery-to-help-locate-neutron-stars-faster/articleshow/19409716.cms