5,706 research outputs found
Constraining fast radio burst progenitors with gravitational lensing
Fast Radio Bursts (FRBs) are new transient radio sources discovered recently.
Because of the angular resolution restriction in radio surveys, no optical
counter part has been identified yet so it is hard to determine the progenitor
of FRBs. In this paper we propose to use radio lensing survey to constrain FRB
progenitors. We show that, different types of progenitors lead to different
probabilities for a FRB to be gravitationally lensed by dark matter halos in
foreground galaxies, since different type progenitors result in different
redshift distributions of FRBs. For example, the redshift distribution of FRBs
arising from double stars shifts toward lower redshift than of the FRBs arising
from single stars, because double stars and single stars have different
evolution timescales. With detailed calculations, we predict that the FRB
sample size for producing one lensing event varies significantly for different
FRB progenitor models. We argue that this fact can be used to distinguish
different FRB models and also discuss the practical possibility of using
lensing observation in radio surveys to constrain FRB progenitors.Comment: 14 pages, including 6 figures and 1 tabl
Search for strong gravitational lensing effect in the current GRB data of BATSE
Because gamma-ray bursts (GRBs) trace the high-z Universe, there is an
appreciable probability for a GRB to be gravitational lensed by galaxies in the
universe. Herein we consider the gravitational lensing effect of GRBs
contributed by the dark matter halos in galaxies. Assuming that all halos have
the singular isothermal sphere (SIS) mass profile in the mass range and all GRB samples follow
the intrinsic redshift distribution and luminosity function derived from the
Swift LGRBs sample, we calculated the gravitational lensing probability in
BATSE, Swift/BAT and Fermi/GBM GRBs, respectively. With an derived probability
result in BATSE GRBs, we searched for lensed GRB pairs in the BATSE 5B GRB
Spectral catalog. The search did not find any convincing gravitationally lensed
events. We discuss our result and future observations for GRB lensing
observation.Comment: 18 pages, 8 figure
Dibromidobis[1-(2-bromoÂbenzÂyl)-3-(pyrimidin-2-yl)-1H-imidazol-2(3H)-one]copper(II)
In the title complex, [CuBr2(C14H11BrN4O)2], the CuII ion is located on an inversion centre and is coordinated by two ketonic O atoms, two N atoms and two Br atoms, forming a distorted octahedral coordination environment. The two carbonyl groups are trans positioned with C=O bond lengths of 1.256 (5) Å, in agreement with a classical carbonyl bond. The Cu—O bond length is 2.011 (3) Å. The two bromoÂbenzyl rings are approximately parallel to one another, forming a dihedral angle of 70.1 (4)° with the coordination plane
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