3 SPECTRAL STATES OF 1E-1740.7 - 2942 - FROM STANDARD CYGNUS-X-1 TYPE SPECTRUM TO THE EVIDENCE OF ELECTRON-POSITRON ANNIHILATION FEATURE

被引：144

作者：

SUNYAEV, R

CHURAZOV, E

GILFANOV, M

PAVLINSKY, M

GREBENEV, S

BABALYAN, G

DEKHANOV, I

KHAVENSON, N

BOUCHET, L

MANDROU, P

ROQUES, JP

VEDRENNE, G

CORDIER, B

GOLDWURM, A

LEBRUN, F

PAUL, J

机构：

[1] CTR ETUD SPATIALE RAYONNEMENTS,F-31029 TOULOUSE,FRANCE

[2] CENS,SERV ASTROPHYS,F-91191 GIF SUR YVETTE,FRANCE

来源：

ASTROPHYSICAL JOURNAL | 1991年 / 383卷 / 02期

关键词：

BLACK HOLES; GALAXIES THE GALAXY; GAMMA-RAYS GENERAL; X-RAYS; SOURCES;

D O I：

10.1086/186238

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The source 1E 1740.7-2942 is known to be the brightest hard X-ray source close to the dynamic center of our Galaxy. Three apparently different spectral states of this source were detected by the GRANAT observatory during 1990-1991 observations of the Galactic Center (GC) region. In almost all 1990 observations the source had Cyg X-1-like spectrum with nearly constant flux. The hardest of the states (observed on 1990 October 13-14) exhibits a prominent high-energy bump on the spectrum at 300-600 keV, probably related to the annihilation processes in relatively cold electron-positron plasma. In the most recent measurements on 1991 February-March a long-term low state of 1E 1740.7-2942 was discovered with the source flux on the level of 15%-20% of its 1990 value.

引用

页码：L49 / L52

页数：4