6,028 research outputs found
Coalescence Rate of Supermassive Black Hole Binaries Derived from Cosmological Simulations: Detection Rates for LISA and ET
The coalescence history of massive black holes has been derived from
cosmological simulations, in which the evolution of those objects and that of
the host galaxies are followed in a consistent way. The present study indicates
that supermassive black holes having masses greater than underwent up to 500 merger events along their history. The derived
coalescence rate per comoving volume and per mass interval permitted to obtain
an estimate of the expected detection rate distribution of gravitational wave
signals ("ring-down") along frequencies accessible by the planned
interferometers either in space (LISA) or in the ground (Einstein). For LISA,
in its original configuration, a total detection rate of about is
predicted for events having a signal-to-noise ratio equal to 10, expected to
occur mainly in the frequency range . For the Einstein gravitational
wave telescope, one event each 14 months down to one event each 4 years is
expected with a signal-to-noise ratio of 5, occurring mainly in the frequency
interval . The detection of these gravitational signals and their
distribution in frequency would be in the future an important tool able to
discriminate among different scenarios explaining the origin of supermassive
black holes.Comment: 18 pages, 7 figures, to appear in the IJMP
Gravitational Waves from Wobbling Pulsars
The prospects for detection of gravitational waves from precessing pulsars
have been considered by constructing fully relativistic rotating neutron star
models and evaluating the expected wave amplitude from a galactic source.
For a "typical" neutron matter equation of state and observed rotation rates,
it is shown that moderate wobble angles may render an observable signal from a
nearby source once the present generation of interferometric antennas becomes
operative.Comment: PlainTex, 7 pp. , no figures, IAG/USP Rep. 6
O potencial da pecuária de corte nas regiões tropicais e subtropicais da América Latina.
Vantagens e limitações oferecidas pelos trópicos à produção de bovinos de corte. Estágio de desenvolvimento da pecuária bovina de corte. Mercado consumidor de carne. Potencial do aumento de produção de carne bovina na América Latina.bitstream/item/104684/1/Potencial-da-pecuaria-de-corte.pd
Estimativa do custo de producao da carne bovina para a regiao Centro-oeste: setembro de 1986.
bitstream/item/138579/1/COT-30.pdfCNPGC
The Globular Cluster System of NGC 5128 II. Ages, Metallicities, Kinematics, and Formation
We present a study of the nearby post-merger giant elliptical galaxy, NGC
5128 (Centaurus A), in which we use the properties of its globular cluster (GC)
and planetary nebula (PN) systems to constrain its evolution. Using photometric
and spectroscopic data for 215 GCs presented in Paper I, we study trends in
age, metallicity, and kinematics for the GC system. We confirm that the GC
metallicity distribution is bimodal, and show that these two sub-populations
have different properties. Using spectral line index measurements of the
brightest clusters, the metal-poor GCs have old ages like the Milky Way
globular clusters, while the metal-rich GCs have H-beta line-strengths that
could be interpreted as a mean age of ~5 (+3/-2) Gyr. Both populations appear
to have [Mg/Fe] ratios consistent with that of the Galactic GC system, although
this quantity is not very well-constrained. The kinematics of the metal-rich
GCs are similar to those of the planetary nebulae, exhibiting significant
rotation about a misaligned axis, while the metal-poor GCs have a higher
velocity dispersion and show a weaker kinematic correlation with the field
stars. The total gravitating mass of NGC 5128 derived from the GCs is in
excellent agreement with the value derived from stellar (PN) kinematics. We
suggest that these and other data support a picture in which the main body of
NGC 5128 was formed 3-8 Gyr ago by the dissipational merger of two unequal-mass
disk galaxies supplemented by the continual accretion of both gas-rich and
gas-poor satellites.Comment: 15 pages, 21 figures (figures 14-20 best viewed in color), accepted
for publication in the Astrophysical Journa
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