Search for Outbursts in the Narrow 511-keV Line from Compact Sources Based on INTEGRAL Data

Abstract

We present the results of a systematic search for outbursts in the narrow positron annihilation line on various time scales (5x10^4 - 10^6 s) based on the SPI/INTEGRAL data obtained from 2003 to 2008. We show that no outbursts were detected with a statistical significance higher than ~6 sigma for any of the time scales considered over the entire period of observations. We also show that, given the large number of independent trials, all of the observed spikes could be associated with purely statistical flux fluctuations and, in part, with a small systematic prediction error of the telescope's instrumental background. Based on the exposure achieved in ~6 yr of INTEGRAL operation, we provide conservative upper limits on the rate of outbursts with a given duration and flux in different parts of the sky.

16 pages, 8 figures. To be published in Astronomy Letters, 2010, Vol. 36, No 4, p. 237

References in corpus (5)

• The all-sky distribution of 511 keV electron-positron annihilation emission
• Positron annihilation spectrum from the Galactic Center region observed by SPI/INTEGRAL
• Unveiling the high energy tail of 1E 1740.7-2942 with INTEGRAL
• A Comprehensive Search for Gamma-Ray Lines in the First Year of Data from the INTEGRAL Spectrometer
• On the Origin of the 511 keV Emission in the Galactic Centre

Cited by in corpus (5)

• Positron annihilation spectrum from the Galactic Centre region observed by SPI/INTEGRAL, revisited: annihilation in a cooling ISM?
• Catalog of Short Gamma-Ray Transients Detected in the SPI/INTEGRAL Experiment
• INTEGRAL 11-year hard X-ray survey above 100 keV
• Black holes: Timing and spectral properties and evolution
• 15 years of Galactic surveys and hard X-ray Background measurements