XMM-Newton Trainee Project 2004

Florencia Jimenez Lujan

I was born in Alcorcón, near Madrid, Spain. I studied Physics at UCM (Universidad Complutense de Madrid). During my last course, I worked within the Pre-Graduate Trainee Program at XMM-Newton Science Operations Center, European Space Astronomy Center (ESAC).

My project consisted of analyzing the nearby spiral galaxy M 83, under the supervision of my tutor, Dr. Matthias Ehle. M 83, also called NGC 5236, is a bright barred spiral galaxy with an active starburst nucleus. It has been the target of numerous astrophysical investigations because of its proximity. Its distance was recently estimated to be 4.5 Mpc but it is still very uncertain. Since it is seen almost face-on and lies in a direction of the southern sky with low Galactic absorption, M 83 is an ideal candidate to study X-ray emission components.

M 83 was observed with the XMM-Newton Observatory on January 27, 2003. About one year later, our data was collected from the XMM-Newton Archive (XSA) and then processed with some tasks from the Science Analysis Subsystem (SAS) software package. We mainly used data from the three EPIC (European Photon Imaging Camera) cameras, one CCD-pn detector and the other two CCD-MOS detectors, in order to obtain our results.

Firstly, we obtained X-ray images for different energy bands and created a false color image as a combination of three of these bands (see Fig. 1, left panel). In this image, we could see clearly the extended soft (red) diffuse emission around the nucleus and some point-like sources emitting harder (bluer) X-ray. In addition, we created an image of M 83 combining an optical image and an X-ray contour map for the broad energy band (see Fig. 1). With it, since the contours are calculated with the count rate, we can get an idea of the dimensions of the diffuse emission and the X-ray point-like sources.


Fig 1.Left panel: False color image of the galaxy M 83.
Color code: Red: 0.2 - 1.0 KeV; Green: 1.0 - 2.0 KeV; Blue: 2.0 - 12.0 KeV.
Right panel: Optical image: Anglo-Australian Observatory (David Malin). X-ray contour map: 0.2 - 12.0 KeV.


Secondly, we detected the point-like sources in the field of view and listed them in a catalogue with their position (and their errors) and some of their properties. We made a spectral analysis of selected point-like X-ray sources and extended emission. Our models with XSPEC confirmed the expectation that one observes a superposition of a soft halo and hard disk emission in face-on galaxies.

We also calculated light curves to see the variability of the sources in the X-ray regime and hardness ratio diagrams to study how soft or hard the X-ray emission is of the sources. With this information, we could classify the brightest sources.

Finally, we calculated the luminosities for different components of the galaxy M 83, with which we will be able to calculate other important parameters of the galaxy in the near future.