precessing binaries: astrophysical expectations
DESCRIPTION
Precessing Binaries: Astrophysical Expectations. Vicky Kalogera Physics & Astronomy Dept Northwestern University with Philippe Grandclement Mia Ihm. Precession and Inspiral Waveforms. Compact object binaries can precess if spins are of significant magnitude and misaligned with - PowerPoint PPT PresentationTRANSCRIPT
Precessing Binaries: Precessing Binaries: Astrophysical ExpectationsAstrophysical Expectations
Vicky KalogeraPhysics & Astronomy DeptNorthwestern University
with
Philippe GrandclementMia Ihm
Precession and Inspiral Waveforms
Compact object binaries can precess if spins are of significant magnitude and misaligned with
respect to the orbital angular momentum.
Precession can modify inspiral waveforms and decrease the detection efficiency of standard non-precession searches.
Precession effects are more important for binaries of high mass ratios (BH-NS) and with spin tilt angles
of the massive object in excess of ~30°.(Apostolatos 95)
Q: What is the origin of spin tilt angles in compact object binaries ?
Mass transfer episodes in binaries tend to align spin and orbital angular momentum vectors.
BH
SN + NS kick SN + NS kick
BHNS
Asymmetric supernova explosions can tilt the orbital plane relative to the spin of the non-exploding star.
Q: What are the expected spin tilt angles ?
BH-NS binaries are expected to have significant spin tilt angles
10 Mo BH
1.4 Mo NS
VK 2000
BH-NS
Grandclement et al. 2003
> model BH-NS progenitors and SN kick effects
Grandclement, VK, Vecchio 2002Grandclement & VK 2003Grandclement, Ihm, VK, Belczynski 2003Buonanno et al. 2003Pan et al. 2003
with non-precessing templates: detection rate decreasesR
det decrease depends on
spin magnitude and tilt angle:
cos(spin tilt angle)
Maximum BH spin
cos(spin tilt angle)
templates that can mimicthe precession effects can increase the detection rate:
Precessing inspiral binariesPrecessing inspiral binaries
For a 10-1.4 Mo BH-NS binary
3
BH spin magnitude
BH-NS
Rate drop expected Rate drop expected from from astrophysical predictionsastrophysical predictions for spin tilts in BH-NS binariesfor spin tilts in BH-NS binaries
Grandclement, Ihm, VK, Belczynski 2003
rate dropby 20-30%
BH-NS
Expected rates:
BH-NS1.5 -1500 per yr3x10-4 -0.3
BH-BH15 -10,000 per yr4x10-3 -3