Gravitational Waves from Boson Stars

Transcription

1 Gravitational Waves from Boson Stars Ruxandra Bondarescu (ICG, Portsmouth) Gregory Daues (NCSA) Jayashree Balakrishna (Harris Stowe State U) Edward Seidel (NCSA) CQG 23, 2631 (2006), gr-qc/ , Phys. Rev. D 73, (R) (2006), gr-qc/ , Phys. Rev. D 77, (2008), gr-qc/ Restarted, Work in Progress, to be submitted 2017!

2 The month before Me and Ed when we started collaborating 2

3 Measuring them feels impossible. But impossible things must be tried and when you spent a billion dollars, failure s not an easy option. Since then LIGO found GWs The LIGO collaboration has 1000 people (Edward Lundgren, David Bondarescu et al., 2016) 3

4 Gravitational Waves: Detections!!! 4

5 LIGO + VIRGO 5

6 GW Observations so far Compact objects of a few to 30some M Sun Inspiral and merger So far matched to numerical relativity Could see from M Sun up to M Sun Shown that 10+ M Sun exist Fewer at 100 M Sun? Too similar to glitches? Are these black holes or boson stars or some other kind of compact object? 6

7 What are boson stars Simplest boson star formed from fundamental spin zero particles represented by a complex scalar field Supported against gravitational collapse purely by Heisenberg s Uncertainty Principle Mathematically: localized solutions to the coupled Einstein-Klein- Gordon equations The concept of radius of a BS is not well defined φ tails off exponentially but, φ does not reach zero until radial infinity => nonzero probability of finding a boson at any radius. Numerically, for convenience we define a radius e.g, distance within which 95% of the total mass is present. 7

8 Why are boson stars interesting Potential gravitational wave sources Rich behavior : can pass through each other, recoil or coalesce Rotating boson stars - quantized states. Only rapidly rotating can rotate only differentially, Ground state: lowest energy configuration Dark matter candidates Even lighter bosons proposed as ultra-light dark matter (Hu et al. 2000, Hui,Ostriker, Tremaine & Witten et al arxiv: ), solves missing satellites problem Scalar fields needed in particle physics: Higgs, axion, etc 8

9 What could LIGO see Dark mattter condensates from light bosons of m ~ ev M Pl 2 /m ~ kg~10-19 M sun, for m=1 GeV M Pl 2 /m ~ 10 M sun for m=10-11 ev Radius ~ 12 km for m = ev A black hole of the same M, R ~ 3 km Additional parameters can be added, e.g., self-coupling Hunting for Dark Particles w. GW, Giudice et al

10 Boson Stars in 3D Massive complex scalar field φ in General Relativity L=R/16 π G - µ φ * µ φ - m 2 φ * φ 3D code based on the Einstein Toolkit McLachlan implementation of BSSN method of lines MoL::ODE_Method = "rk4 Scalar field evolution: KomplexSF thorn : ICN3 TmunuBase support_old_calctmunu_mechanism = "yes Initial data: 1D spherical data interpolated + small perturbation Initial Value Problem Solver : TATPETSc 1+log slicing, zero shift γ ij = Ψ 4 γ ij_guess 10

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14 Nonradial QNM of boson stars (Eriguci, Yoshida, Futamase, 1994) Macedo et al. 2013, different? Field extends to infinity =>gravitational radiation can escape to infinity Only, strongly damped modes Contrast with neutron stars - both weakly and strongly damped modes (w-modes) Large imaginary part Contrast to BH Imaginary part grows slowly with mode index Waveforms not dominated by the two lowest modes 14

15 Potential Future directions Identify smoking gun signatures for detection Check numerical results vs. quasinormal modes from WKB & continued fractions Generate/predict waveforms for binary bosonic systems Solve momentum constraint? Tidal effects? accretion disks around boson stars/soliton stars? Size of kicks generated by boson stars? small BHs? drain-like accretion of stars? 15

16 The End 16