Lok Sabha Question No. 3912 (UNSTARRED), answered on 2016-08-10
Subject: Detection of Gravitational Waves
Ministry: ATOMIC ENERGY
Asked by: RAKSHA NIKHIL KHADSE, NANABHAU FALGUNRAO PATOLE

## GOVERNMENT OF INDIA DEPARTMENT OF ATOMIC ENERGY

## LOK SABHA

## UNSTARRED QUESTION NO. 3912

TO BE ANSWERED ON 10.08.2016

## DETECTION OF GRAVITATIONAL WAVES

## 3912.  SHRIMATI RAKSHATAI KHADSE: SHRI NANA PATOLE:

Will the PRIME MINISTER be pleased to state:

- (a) whether  a  team  of  scientists  across  the  world  has  confirmed  detection  of gravitational  waves  from  binary  black  hole  merger  and  if  so,  the  details thereof;
- (b) whether Indian scientists too have hailed the said phenomenon and if so, the details thereof; and
- (c) the  studies  made  by  Indian  scientists  in  this  area  along  with  the  outcome thereof?

## ANSWER

THE  MINISTER  OF  STATE  FOR,  PERSONNEL,  PUBLIC  GRIEVANCES  AND PENSIONS AND PRIME MINISTER'S OFFICE (DR. JITENDRA SINGH):

- (a) Yes, Sir.  Two Laser Interferometric Gravitational-wave Observatories (LIGO) in the USA have detected signals from two confirmed events involving merger of black holes in the distant universe.  The first on September 14, 2015 and the second on December  24, 2015. The international LIGO  Science collaboration consisting of about 1000  scientists from universities and research  institutes  from  about  15  countries,  including  India,  announced  the first detection on February 5, 2016 and second one on June 15, 2016.
- (b) The Indian science community has hailed these discoveries and is proud of the significant contribution from India.  There was a very significant presence of  Indian  scientists  in  this  milestone  scientific  achievement.    There  are  37 authors  from  9  Indian  Institutions  in  the  scientific  publication  presenting  the first discovery of Gravitational waves published in the Physical Review letters by the LIGO Scientific Collaboration and Virgo Collaboration.  There were 39

authors from the same 9 Indian institutions in the publication for the detection of the second black hole merger event.  Currently, Indian participation in the international  LIGO  Science  Collaboration  (LSC),  has  over  60  researchers, constituting  5%  of  the  members  of  the  LSC,  making  us  the  fourth  largest national participant. Indian has 5 members on the LIGO Science Collaboration Council.

- (c) India  can  boast  of  three  decades  of  research  at  Inter  University  Centre  for Astronomy and Astrophysics  (IUCAA),  Pune  and  Raman  Research  Institute (RRI),  Bengaluru,  at  the  frontiers  of  theoretical  modelling,  and  developing algorithms  for  signal  extraction,  in  the  quest  for  discovering  gravitational waves. Some  of  these  contributed  directly to the detection and  are prominently  cited  in  these  discovery  publications.    Specific  contributions  by Indian  researchers  include  the  development  of  a  signal  processing  method called Matched Filtering - a key analysis technique needed for this detection, (pioneered  at  IUCAA)  the  estimation  of  black  hole  binary  parameters,  in improving  the  estimation  accuracy  of  black  hole  spins,  efficient  methods  for handling  instrumental  artefacts,  and  electromagnetic  follow-up  with  X-ray instrument  onboard  AstroSat,  which  is  a  space  borne  facility  launched  by Indian Space Research Organisation (ISRO).  India is also committed to the mega  science LIGO-India project, to build and operate an  advanced gravitational wave observatory on Indian soil.

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