arXiv subjects

Bohdan Paczynski

Publications and source records attributed to Bohdan Paczynski.

38 records · Page 3Linked to original sources

arXiv1994

Gravitational Microlensing by the Globular Cluster Stars

The microlensing of background stars by compact objects in globular clusters is analyzed. The main strength of the proposed search is the direct relationship between the lens mass and the time scale of the microlensing event. The main problem is the low overall rate of expected events which implies that a ground based search should last for about a decade to generate a non trivial number of events, like a few dozen. A space borne experiment could increase the rate by a large factor by increasing the number of stars which could be monitored thanks to the much better seeing. The clusters M22 with the galactic bulge background, and 47 Tuc with the SMC background, are the two examples of possible targets.

astro-ph↗

arXiv1993

Radio Transients from Gamma-Ray Bursters

The rapid time variability of gamma-ray bursts implies the sources are very compact, and the peak luminosities are so high that some matter must be ejected at ultra-relativistic speeds. The very large Lorentz factors of the bulk flow are also indicated by the very broad and hard spectra. It is natural to expect that when the relativistic ejecta interact with the interstellar matter a strong synchrotron radio emission is generated, as is the case with supernova remnants and radio galaxies. We estimate that the strongest gamma-ray bursts may be followed by radio transients with peak fluxes as high as 0.1 Jy. The time of peak radio emission depends on the distance scale; it is less than a minute if the bursts are in the galactic halo, and about a week if the bursts are at cosmological distances.

astro-ph↗