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Gravitational Wave Sources near 1 Hz Avetis Abel Sadoyan

Mathew Benacquista Montana State University- Billings. D.Sedrakian, M.Hairapetyan, K. Shahabasyan Yerevan State University. Gravitational Wave Sources near 1 Hz Avetis Abel Sadoyan. CRDF/NFSAT Award # ARP2-3232-YE-04. Outline. White dwarf frequencies

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Gravitational Wave Sources near 1 Hz Avetis Abel Sadoyan

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  1. Mathew Benacquista Montana State University-Billings D.Sedrakian, M.Hairapetyan, K. Shahabasyan Yerevan State University Gravitational Wave Sources near 1 HzAvetis Abel Sadoyan CRDF/NFSAT Award #ARP2-3232-YE-04 Gravitational Wave Advanced Detectors Workshop

  2. Outline • White dwarf frequencies • Gravitational radiation mechanisms • Stochastic background level near 1 hz Gravitational Wave Advanced Detectors Workshop

  3. Why White Dwarfs? NS WD Gravitational Wave Advanced Detectors Workshop

  4. Why White Dwarfs? • White Dwarfs(WD) are stellar configurations with central densities ~106-109 g/ cm3 -they are on the border between normal stars and relativistic configurations • Quadrupole moment of WDs is Q~1048g cm2 - several orders higher then Neutron Star’s Quadrupole moment Gravitational Wave Advanced Detectors Workshop

  5. Why White Dwarfs ? • White Dwarfs(WD) are the most close potential sources of GWs - there are White Dwarfs at 8 pc distance. • WD Population is estimated about ~108 in the Galaxy -WDs are the largest population among potential astrophysical sources of GWs Gravitational Wave Advanced Detectors Workshop

  6. Strain Amplitudes • Oblate shape due to rotation • Oscillation is self-similar and is described by: • Quadrupole moment Choose z-axis along rotation axis: Q0zz=–2Q0xx=–2Q0yy=–2Q0 Gravitational Wave Advanced Detectors Workshop

  7. Polarizations In TT gauge with z-axis along the wave vector: where  is the angle between the wave vector and the white dwarf axis of rotation Gravitational Wave Advanced Detectors Workshop

  8. Gravitational Radiation Intensity Gravitational Wave Advanced Detectors Workshop

  9. White Dwarf Properties and Resonant Frequencies Gravitational Wave Advanced Detectors Workshop

  10. Frequency Range of WD Oscillations Central density Gravitational Wave Advanced Detectors Workshop

  11. Deformation Energy • M and Mo are mass of rotating and non-rotating configurations with same complete number of baryons N Gravitational Wave Advanced Detectors Workshop

  12. White Dwarfs Maximal deformation Energy versus Central density Gravitational Wave Advanced Detectors Workshop

  13. GW Amplitudes from WDs rotating with Keplerian angular velocities Gravitational Wave Advanced Detectors Workshop

  14. Mechanisms of GW Radiation • GWs from Magnetized WDs: -deformation energy is feeding oscillations -magnetodipol radiation torque is breaking rotation • GWs from differentially rotating WDs • GWs from triaxial WDs Gravitational Wave Advanced Detectors Workshop

  15. Types of Models of WDs • Model 1.a is calculated by requiring that the largest Doppler broadening of spectral lines due to pulsations be less than thermal Doppler broadening • Model 1.m is based on assumption that all non-dissipated part of deformation energy is going to oscillations, it is maximal possible model to that sense. Gravitational Wave Advanced Detectors Workshop

  16. GWs from Magnetized WDs 1.a Gravitational Wave Advanced Detectors Workshop

  17. GWs from Magnetized WDs 1.m Gravitational Wave Advanced Detectors Workshop

  18. Differentially Rotating WDs model 2.1 Gravitational Wave Advanced Detectors Workshop

  19. Differentially Rotating WDs model 2.2 Gravitational Wave Advanced Detectors Workshop

  20. Triaxsial WDs model 3.r • Rotating triaxsial ellipsoid Gravitational Wave Advanced Detectors Workshop

  21. Triaxsial WDs model 3.n • Non Rotating, oscillating triaxsial ellipsoid Gravitational Wave Advanced Detectors Workshop

  22. Stochastic background level • Background is not isotropic: Assuming a galactic distribution of white dwarfs to follow the disk population, we assign a density distribution of WDs: in galacto-centric cylindrical coordinates, with R0=2.5kpc and h=200pc Gravitational Wave Advanced Detectors Workshop

  23. Conclusions • Gravitational radiation spectrum near 1 hz is inhabited by Isolated White dwarfs • Model 1.a hav+= 8.35 10-27 • Model 1.m hav+= 7.94 10-25 • Model 2.1 hav+= 2.01 10-25 • Model 2.2 hav+= 1.62 10-25 • Standard inflation gives h~10-27–10-29 in this frequency range. Gravitational Wave Advanced Detectors Workshop

  24. Equation of State for White Dwarfs • where Gravitational Wave Advanced Detectors Workshop

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