Physics

Study findings on astronomy are outlined in reports from University of Melbourne

  2010 FEB 9 - (VerticalNews.com) -- According to recent research from Parkville, Australia, "The mean-square current quadrupole moment associated with vorticity fluctuations in high-Reynolds-number turbulence in a differentially rotating neutron star is calculated analytically, as are the amplitude and decoherence time of the resulting, stochastic gravitational wave signal. The calculation resolves the subtle question of whether the signal is dominated by the smallest or largest turbulent eddies: for the Kolmogorov-like power spectrum observed in superfluid spherical Couette simulations, the wave strain is controlled by the largest eddies, and the decoherence time approximately equals the maximum eddy turnover time."

  "For a neutron star with spin frequencys and Rossby number Ro, at a distance d from Earth, the root mean square wave strain reaches h(rms) approximate to 3 x 10(-24) Ro(3)(nu(s)/30 Hz)(3)(d/1 kpc)(-1). Ordinary rotation-powered pulsars (nu(s) less than or similar to 30 Hz, Ro less than or similar to 10(-4)) are too dim to be detected by the current generation of long-baseline interferometers," wrote A. Melatos and colleagues, University of Melbourne.

  The researchers concluded: "Millisecond pulsars are brighter; for example, an object born recently in a Galactic supernova or accreting near the Eddington rate can have nu(s) similar to 1kHz, Ro greater than or similar to 0.2, and hence h(rms) similar to 10(-21)."

  Melatos and colleagues published their study in Astrophysical Journal (GRAVITATIONAL RADIATION FROM HYDRODYNAMIC TURBULENCE IN A DIFFERENTIALLY ROTATING NEUTRON STAR. Astrophysical Journal, 2010;709(1):77-87).

  For additional information, contact A. Melatos, University of Melbourne, Sch Phys, Parkville, Vic 3010, Australia.

  Publisher contact information for the Astrophysical Journal is: IOP Publishing Ltd., Dirac House, Temple Back, Bristol BS1 6BE, England.

  Keywords: City:Parkville, Country:Australia, Gravitational Radiation, Gravitational Waves, Physics, Supernovas, Astronomy, University of Melbourne.

  This article was prepared by VerticalNews Physics editors from staff and other reports. Copyright 2010, VerticalNews Physics via VerticalNews.com.