We present BeppoSAX results on the near-by star burst galaxy NGC 253. Although extended, a large fraction of the X-ray emission comes from the nuclear region. Preliminary analysis of the LECS/MECS/PDS similar to 0.2-60 keV data from the central 4' region indicates that the continuum is well fitted by two thermal models: a "soft" component with kT similar to 0.9 keV, and a "hard'' component with kT similar to 6 keV absorbed by a column density of similar to 1.2 x 10(22) cm(-2). For the first time in this object, the Fe K line at 6.7 keV is detected, with an equivalent width of similar to 300 eV. This detection, together with the shape of the 2-60 keV continuum, implies that most of the hard X-ray emission is thermal in origin, and constrains the iron abundances of this component to be similar to 0.25 of solar. Other lines clearly detected are Si, S and Fe L/Ne, in agreement with previous ASCA results. We discuss our results in the context of the starburst-driven galactic superwind model.
BeppoSAX detection of the Fe K line in the nearby starburst galaxy NGC 253
Danese, Luigi;Salucci, Paolo;
1998-01-01
Abstract
We present BeppoSAX results on the near-by star burst galaxy NGC 253. Although extended, a large fraction of the X-ray emission comes from the nuclear region. Preliminary analysis of the LECS/MECS/PDS similar to 0.2-60 keV data from the central 4' region indicates that the continuum is well fitted by two thermal models: a "soft" component with kT similar to 0.9 keV, and a "hard'' component with kT similar to 6 keV absorbed by a column density of similar to 1.2 x 10(22) cm(-2). For the first time in this object, the Fe K line at 6.7 keV is detected, with an equivalent width of similar to 300 eV. This detection, together with the shape of the 2-60 keV continuum, implies that most of the hard X-ray emission is thermal in origin, and constrains the iron abundances of this component to be similar to 0.25 of solar. Other lines clearly detected are Si, S and Fe L/Ne, in agreement with previous ASCA results. We discuss our results in the context of the starburst-driven galactic superwind model.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
