GW151226 – Twin ‘LIGO’s detect another Binary Black Hole merger

Detection of GW151226

On December 26, 2015 at 09:09AM IST the LIGO detectors in Hanford, Washington and Livingston, Louisiana detected a signal from the coalescence of two black holes, with masses 14 and 8 times the mass of the sun, merging into a more massive, rapidly rotating black hole that is 21 times the mass of the sun. The event happened 1.4 billion years ago, lasted in LIGO's frequency band for about a second and released about 1 solar mass worth of energy in that short period.

The GW151226 detection paper: Phys. Rev. Lett. 116, 241103

Specific contributions by IUCAA researchers

  • Matched Filtering
    • A key analysis technique needed for this detection, pioneered at IUCAA
    • Several refinements to the original analysis (e.g., to include multiple detectors)
  • Estimation of Black Hole Binary parameters
    • In improving the estimation accuracy of Black Hole spins
  • Efficient methods for handling instrumental artefacts
  • Electromagnetic followup with CZTI instrument onboard AstroSat
  • Towards building a LIGO detector in India
    • To dramatically improve the accuracy for estimation of location and orientation
  • Developing search algorithms for Stochastic backgrounds
    • A stochastic background from binary black-holes may be detectable by advanced LIGO

Parameters of the black holes

Masses of primary black holes: 14 and 8 (solar units)
Mass and spin of the merged BH: 21 (solar units) and 0.74 (dimensionless)

Distance of event:
440 Megaparsec or 1.4 billion Light Years (1.357698136e+22 km)

Gravitational Wave signal:
Date of Arrival: 26th Dec 2015
Time of Arrival: 09:09 AM IST

Energy released in the form of GWs: equivalent of 1 solar mass (remember E = mc2)!

Watch the LIGO-Virgo Press Conference

Wednesday, June 15, 2016 10:15 AM US PDT/1:15 PM US EDT

The international collaborators will comment on their ongoing research, at their first press conference since the historic observation of gravitational waves.
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