We describe the first XMM-Newton observations of the starburst galaxy NGC~253 .
As known from previous X-ray observations , NGC~253 shows a mixture of extended ( disk and halo ) and point-source emission .
The high XMM-Newton throughput allows a detailed investigation of the spatial , spectral and variability properties of these components simultaneously .
We characterize the brightest sources by their hardness ratios , detect a bright X-ray transient \sim 70″ SSW of the nucleus , and show the spectrum and light curve of the brightest point source ( \sim 30″ S of the nucleus , most likely a black-hole X-ray binary , BHXRB ) .
The unresolved emission of two disk regions can be modeled by two thin thermal plasma components ( temperatures of \sim 0.13 and 0.4 keV ) plus residual harder emission , with the lower temperature component originating from above the disk .
The nuclear spectrum can be modeled by a three temperature plasma ( \sim 0.6 , 0.9 , and 6 keV ) with the higher temperatures increasingly absorbed .
The high temperature component most likely originates from the starburst nucleus , as no non-thermal component , that would point at a significant contribution from an active nucleus ( AGN ) , is needed .
Assuming that type IIa supernova remnants ( SNRs ) are mostly responsible for the E > 4 keV emission , the detection with EPIC of the 6.7 keV line allows us to estimate a supernova rate within the nuclear starburst of 0.2 yr ^ { -1 } .
The unprecedented combination of RGS and EPIC also sheds new light on the emission of the complex nuclear region , the X-ray plume and the disk diffuse emission .
In particular , EPIC images reveal that the limb-brightening of the plume is mostly seen in higher ionization emission lines , while in the lower ionization lines , and below 0.5 keV , the plume is more homogeneously structured .
The plume spectrum can again be modeled by a three temperature thermal plasma containing the two low temperature nuclear components ( though less absorbed ) plus an unabsorbed 0.15 keV component similar to the disk spectra .
This points to new interpretations as to the make up of the starburst-driven outflow .