Observation of hard X-ray emission from extragalactic sources 3C 273 and NGC 5506 in 20-200 keV band

Abstract

We report spectral measurements of the bright QSO 3C273 and the AGN source NGC 5506 made during a balloon flight experiment using high sensitivity scintillation counter telescope LASE, operating in the 20-200 keV energy band. The observations were made on Nov. 20, 1998 from Hyderabad, S. India. The observed spectrum for 3C 273 and is best fitted with a power law of the form = KE-? and the measure luminosity compares with earlier measurements by SIGMA and OSSE satellites. The observed spectra of NGC 5506 was found to be very hard although the total luminosity was much lower than the earlier observations and is consistent with the time variability of the AGN sources, Spectral data is discussed in terms of non-thermal emission models and X-ray emission geometry.