The detection of Gamma Ray Burst GRB990705 on 1999, July 5.66765 UT, %on July 5$^{th}$ 1999 pointing to the Large Magellanic Clouds, suggested the search for a possible neutrino counterpart, both in coincidence with and slightly before (or after) the photon burst. We exploited such a possibility by means of the LVD neutrino telescope (National Gran Sasso Laboratory, Italy), which has the capability to study low-energy cosmic neutrinos. No evidence for any neutrino signal, over a wide range of time durations, has been found, at the occurrence of GRB990705. Due to the lack of information about both the source distance and its emission spectrum, the results of the search are expressed in terms of upper limits, at the Earth, to the $\bar{\nu}_e$ flux $\cdot$ cross-section, integrated over different time durations, $\int \int \Phi_{\bar \nu_e}\sigma dE dt$. Moreover, assuming thermal $\bar\nu_e$ spectra at the source, upper limits to the $\bar\nu_e$ flux, integrated over time duration, for different spectral temperatures, are obtained. Based on these limits and on the expectations for $\nu$ emission from collapsing astrophysical objects, the occurrence of a gravitational stellar collapse can be excluded up to a distance $r \approx 50$ kpc, in the case of time coincidence with GRB990705, and $r \approx 20$ kpc, for the 24 hours preceding it.
Upper limits to the low energy electron-antineutrino flux from GRB990705
2001
Abstract
The detection of Gamma Ray Burst GRB990705 on 1999, July 5.66765 UT, %on July 5$^{th}$ 1999 pointing to the Large Magellanic Clouds, suggested the search for a possible neutrino counterpart, both in coincidence with and slightly before (or after) the photon burst. We exploited such a possibility by means of the LVD neutrino telescope (National Gran Sasso Laboratory, Italy), which has the capability to study low-energy cosmic neutrinos. No evidence for any neutrino signal, over a wide range of time durations, has been found, at the occurrence of GRB990705. Due to the lack of information about both the source distance and its emission spectrum, the results of the search are expressed in terms of upper limits, at the Earth, to the $\bar{\nu}_e$ flux $\cdot$ cross-section, integrated over different time durations, $\int \int \Phi_{\bar \nu_e}\sigma dE dt$. Moreover, assuming thermal $\bar\nu_e$ spectra at the source, upper limits to the $\bar\nu_e$ flux, integrated over time duration, for different spectral temperatures, are obtained. Based on these limits and on the expectations for $\nu$ emission from collapsing astrophysical objects, the occurrence of a gravitational stellar collapse can be excluded up to a distance $r \approx 50$ kpc, in the case of time coincidence with GRB990705, and $r \approx 20$ kpc, for the 24 hours preceding it.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
