Research Area: Galaxies

My astronomical research areas comprised the investigation of galaxies in different parts of the spectrum, especially starburst galaxies. With the exception of interacting galaxies we do not understand the starburst phenomenon in detail; starbursts can be found in the central regions (and disks) of massive spiral galaxies, but also in low-mass dwarf galaxies where the region of massive star formation may comprise the whole galaxy. In order to understand the mechanisms of starbursts, informations about the ISM in those galaxies, about star formation, mass distribution of stars and star formation efficiency are required.

For this reason I applied for a number of galaxies in different phases of starburst for X-ray observations with the ROSAT satellite. In total we have X-ray data for approximately 25 galaxies from our own applications and collaborations with colleagues; moreover we were using data sets from the ROSAT archive. The X-ray data are complemented by optical, UV- and radio observations.

In the following I will shortly characterize some of these projects:

In case of NGC 1808 we have published two papers (Dahlem et al. 1994, Junkes et al. 1995), with the analysis of the spectral distribution of the X-ray emission and a comparison of luminosity and star formation rate (SFR) with the results from other wavelengths.

A further research project is the investigation of the peculiar S0 galaxy NGC 5128 (Centaurus A) in several radio frequencies, especially the comparison of complete maps of the extended outer radio lobes, covering an area of 9 by 5 degrees in the sky. This project includes the analysis of radio data (with linear polarization---Stokes I,Q,U) in four wavelengths between 21 and 3.5 cm and will allow to investigate polarization properties of the source itself, but also Faraday rotation and depolarization caused by Galactic foreground structures (Galactic spur reaching out to the latitude of Cen A). The results at 6 cm wavelength were published in Astronomy & Astrophysics (Junkes & Haynes 1991).

Together with Stefan Döbereiner (MPE Garching) and Stefan Wagner (MPIA Heidelberg) I worked on the analysis of a very sensitive (65 ksec) high-resolution X-ray observation of the central part of Cen A with the ROSAT HRI detector (Döbereiner et al. 1996).

The collaboration with Gerhard Hensler, now at Vienna University, Daniel Tschöke and Dominik Bomans (Bochum University) has resulted in a number of papers on starburst galaxies, namely NGC1705 (Hensler et al. 1998), NGC4410 (Tschöke et al. 1999), NGC4303 (Tschöke et al. 2000), NGC4569 (Tschöke et al. 2001) and NGC2903 (Tschöke et al. 2003).

Last modified on Tuesday, March 15th, 2022.
Norbert Junkes ( )
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