Khoa Vật lý trân trọng kính mời quý vị đến dự seminar khoa học tháng 8/2017
Ngày: 07/8/2017 (Thứ 2)
Giờ: từ 4 giờ 30 chiều đến 5 giờ 30 chiều
Địa điểm: Phòng 408F, nhà T1, 334 Nguyễn Trãi
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Speaker: Joseph M. Fedrow (Yukawa Institute
for Theoretical Physics, Kyoto University, Japan)
Title: Gravitational Waves from Binary Black Hole Mergers Inside of
Stars
Abstract: We present results from a controlled numerical experiment
investigating the effect of stellar density gas on the coalescence of binary
black holes (BBHs) and the resulting gravitational waves (GWs). This
investigation is motivated by the proposed stellar core fragmentation scenario
for BBH formation and the associated possibility of an electromagnetic
counterpart to a BBH GW event. We employ full numerical relativity coupled with
general-relativistic hydrodynamics and set up a 30+30 solar mass BBH (motivated
by GW150914) inside gas with realistic stellar densities. Our results show that
at densities rho ≳10^6−10^7 g cm^−3
dynamical friction between the BHs and gas changes the coalescence dynamics and
the GW signal in an unmistakable way. We show that for GW150914, LIGO
observations conclusively rule out BBH coalescence inside stellar gas of rho ≳10^7 g cm^−3. Typical densities in the collapsing cores of
massive stars are in excess of this density. This excludes the fragmentation
scenario for the formation of GW150914.
