Gravitational Waves and LIGO India
The Union Cabinet of India has recently approved project to build Laser Interferometer Gravitational-wave Observatories ie, LIGO detectors in Maharashtra in Hingoli district at an estimated cost of Rs 2,600 crore. Hingoli District is situated about 450 km east of Mumbai and its construction is expected to be completed by 2030. Lets get more deeper into Gravitational waves and LIGO detectors.
What are Gravitational Waves ?
Imagine a lake, what happen when you throw a stone inside it ? You will see waves of water right ? So when two blackhole or neutron star merge, it spin around themselves so fast that spacetime surrounding it get converted into wave. It is known as Gravitational waves.
How it all started ?
It all started when On September 14, 2015 at 09:50:45 UTC, the LIGO Hanford and Livingston observatories detected signals from GW150914. At the time of GW150914 Virgo observatory was being upgraded. It was operating but not in observational mode. So LIGO was only observatory which was observing GW150914 at that time and for first time Gravitational waves was detected.
Gravitational waves are very sensitive so we need detectors which are widely separated in order to avoid environmental noise. It consist of two long arms - 4km each, a Laser source, a beam splitter, two test mass on each arms and a Photodetector. Laser is allowed to pass through these long arms. A passing gravitational wave effectively alters the arm lengths. This differential length (infinitely small length) variation alters the phase difference between the two light fields returning to the beam splitter. This transmit an Optical signal which is observed by Photodetector. Transmission of Optical signal is proportional to the gravitational-wave strain. Basic Michelson interferometer are modified inorder to achieve sufficient efficiency.
It all started in 2007 all thanks to Rana Adhikari sir. In 2009 during Australia-India S&T collaboration foundations for Gravitational wave science between India and Australia was setup. In july 2011 IndIGO ie, Indian Initiative in Gravitational-wave Observations was admitted to The Gravitational Wave International Committee. That time India got international recognition of growing Gravitational waves activity and community in India. Then after in October 2011 LIGO-India included in the list of Mega Projects under consideration by the Planning commission. In between September 2011 to September 2016 site selection was carried out.
They were searching for site which was having Low seismicity, Low human generated noise, Facilities like Air, road and data connectivity. Later on they also made use of CARTOSAT satellites for finding proper location as it was having very good resolution and it was capable of generating elevated images. After conducting many test like seismic test, Engineering feasibility study, Weather & Climate study Hangoli district, exact location : 19°36′45″N 77°01′57″E was decided as Final location for setting up LIGO India project. Currently LIGO India’s data center which is operated by IUCAA has enough floor space to host and upgrade ~300TF data centre.
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