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:
-
High-resolution ROSAT observations of nearby irregular galaxies with areas
of massive star formation and pronounced shell structures (like LMC-4 in
the LMC). The project, which is complemented by an optical (spectroscopic)
investigation of the target sources, was done in collaboration with Dominik
Bomans (Urbana-Champaign, USA).
-
Spectral sensitive ROSAT PSPC observations of starburst dwarf galaxies
(BCGs), with high FIR- and radio luminosities which were also investigated
in the radio and in the optical range of the spectrum (collaboration with
Gerhard Hensler and Ralph Dickow
(Universität
Kiel), Uli Klein
(AIfA,
Universität Bonn),
John S. Gallagher (Madison,
USA)).
-
Investigation of the spectral energy distribution in the FIR with
ISO
(collaboration with Gotthard Richter (AIP
Potsdam), Gerhard Hensler (Universität Kiel) and
Harald Krüger, formerly
(MPIA
Heidelberg).
-
Multi-frequency analysis of nuclear starbursts in spiral galaxies NGC 1808,
NGC 2903 und NGC 4569 (together with Hans Zinnecker (AIP Potsdam), Gerhard
Hensler (Universität Kiel) and Michael Dahlem, formerly
(ESA, Nordwijk, and
STScI,
Baltimore, USA).
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 (njunkes@mpifr-bonn.mpg.de
)
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