ISSN:
1572-9672
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Summary On May 8, 1980, we conducted a 90 minute observation on hard X-ray emission (15-200 keV) from Her X-1, using a large area (∼ 1500 cm2), low background balloon borne X-ray telescope. The energy resolution of the telescope was ∼ 17% FWHM at 60 keV. Her X-1 was at binary phase 0.0725 and 2.7 ± 0.5 days after turn on in the 35 day cycle. Average pulsation light curves were obtained by sorting data into 25 equal bins, according to pulse arrival time, modulo the 1.24 sec pulsation period. The width of the main pulse is energy dependent and in the 45–75 keV region about 30% smaller than in the range from 15 to 30 keV. The data have been analyzed by taking the Her X-1 pulse minus background spectrum, where the pulse count rate is defined in a pulse phase interval around the pulse maximum of the 1.24 sec period. The background spectrum was intermittently obtained by a chopping collimator system. A spectral feature is present in emission at an energy of 49.5 (+ 1.5, -3) keV and a FWHM of 18 (+ 6, -3) keV and in absorption at an energy of 29.5 (+ 1.7, -1.5) keV and a FWHM of 17.0 (+ 2.6, -2.8) keV. The intensity of this line feature in emission is (1.8 ± 0.4) photons/cm sec. The line excess in emission over the continuum (with kT = 6.75 (+ 0.2, -0.4) keV) is ∼ 7σ.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01246038
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