2,649 research outputs found
The Rate of Short-Duration Gamma-Ray Bursts in the Local Universe
Following the faint gamma-ray burst, GRB 170817A, coincident with a
gravitational wave-detected binary neutron star merger at Mpc, we
consider the constraints on a local population of faint short duration GRBs
(defined here broadly as s). We review proposed low-redshift
short-GRBs and consider statistical limits on a Mpc
population using Swift/Burst Alert Telescope (BAT), Fermi/Gamma-ray Burst
Monitor (GBM), and Compton Gamma-Ray Observatory (CGRO) Burst and Transient
Source Experiment (BATSE) GRBs. Swift/BAT short-GRBs give an upper limit for
the all-sky rate of y at Mpc, corresponding to % of
SGRBs. Cross-correlation of selected CGRO/BATSE and Fermi/GBM GRBs with
Mpc galaxy positions returns a weaker constraint of . A separate search for correlations due to SGR giant flares in nearby
( Mpc) galaxies finds an upper limit of . Our analysis
suggests that GRB 170817A-like events are likely to be rare in existing SGRB
catalogues. The best candidate for an analogue remains GRB 050906, where the
Swift/BAT location was consistent with the galaxy IC0327 at Mpc.
If binary neutron star merger rates are at the high end of current estimates,
then our results imply that at most a few percent will be accompanied by
detectable gamma-ray flashes in the forthcoming LIGO/Virgo science runs.Comment: 16 pages, 4 figures, 1 table. Published in Galaxies as part of the
Special Issue, "Observations and Theory of Short GRBs at the Dawn of the
Gravitational Wave Era
Characterization of Atmospheric Waves at the Upper Clouds in the Polar Region of Venus
Non solar-fixed waves at the cloud tops of the southern polar region of Venus are studied in the winds measured with 3.9 and 5.0 μm images taken by the instrument VIRTIS-M onboard Venus Express. Wavenumbers 1, 2 and 3 are detected, with wave amplitudes ranging from 3.6 to 8.0 m/s. The evolution of the phase has been studied in 16 orbits, finding in a subset of orbits wavenumbers 1 and 2 propagating in different directions (zonal wind), and a westward progression with a phase velocity of approximately 5.7 m/s for the wavenumber 1 in the meridional wind. Finally, a new set of analytical solutions to the atmospheric waves is obtained for the planet Venus, and these are used to characterize the found waves in terms of the horizontal wavelength and phase velocity
- …