## Modeling signals from binaries

Anuradha Gupta works in this area and is a part of the LSC’s waveform review team. Theorists are able to solve Einstein’s equations of gravity to model source waveforms. Knowledge of these waveforms plays a critical role in the search, while corroborating that a signal, if detected, is astronomical in origin with a very high probability.

## Neutron Star Equation of State

Sukanta Bose works in this area for a part of his time. In a recent work he examined the viability of Bose-Einstein condensates (BECs) as candidate states of matter for the interior of neutron stars. Specifically, Chavanis and Harko obtained the mass-radius relation for a BEC star and proposed that the recently discovered neutron stars with masses around 2M⊙ are BEC stars. They employed a barotropic equation of state (EOS), with one free parameter, that was first found by Colpi, Wasserman, and Shapiro (CSW), to describe them and derive stable equilibrium configurations of spinning BEC stars in General Relativity. In a 2015 work we showed that while it is true that BECs allow for compact object masses as heavy as the heaviest observed ones, such stars cannot simultaneously have radii that are small enough to be consistent with the latest observations, in spite of the flexibility available in the EOS in the form of the free parameter. In fact, our conclusion applies to any spinning relativistic boson star that obeys the CSW EOS. While this work in itself did not use any gravitational wave observations, we are exploring how future observations can be incorporated to constrain the neutron star EOS better.

## SELECTED REFERENCES

### Neutron Star Equation of State

- Arunava Mukherjee, Shreya Shah, Sukanta Bose, “Observational constraints on spinning, relativistic Bose-Einstein condensate stars,” Phys. Rev. D91:084051 (2015).
- Dipongkar Talukder, Eric Thrane, Sukanta Bose, Tania Regimbau, “Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background,” Phys. Rev. D 89, 123008 (2014).