My name is Dennis and I am currently working on the Landessternwarte Heidelberg as a PhD student. Together with my supervisor Prof. Dr. Jochen Heidt I am currently working on the integration of the LUCIFER2-Instrument into the Large Binocular Telescope (LBT) on Mt. Graham, Arizona (USA). Our main goal here is to get the instrument comissioned and working properly at the telescope site. Right now we are still testing the functionality in the lab. My contribution is a programm to help observers to prepare their observations in advance, so that no time is lost at the telescope.
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Links: LBT LUCIFER@LBT LUCIFER@RUB |
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| Photo by Marco Pedani | Schematic View of LUCIFER | |
Scientifically we are trying to obtain high-resolution images and spectra of some black hole binary (BHB) candidates. Our aim would be to resolve them spatially, which is quite difficult, as the typical angular separation is less than some 0.000005° (this is comparable to resolving a regular truck on the moon). As the atmosphere is disturbing our sharp view on astronomical objects, we are using a quite tricky method to circumvent this problem - namely adaptive optics (AO). This method allows us to correct for the movement of the atmosphere by projecting some artificial stars into the atmosphere, using some very strong lasers, and measuring their light path disturbance.
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Links: AO@Wikipedia BHB@Wikipedia |
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| Adaptive optics; Image by Stefan Hippler & Andrei Tokovinin (MPIA) |
Hubble Image of NGC 6240 |
Chandra Image of NGC 6240 |
Next to my PhD job I am working as a guide here in order to bring the fascination of astronomy to people willing to obtain more knowledge in this regard. Next to regular guided tours, we also offer observations in the night with a 25cm telescope named 'Bruce'. Despite explaining all this absorbing details to interested people, such an observation is a magnificant compensation for the work-intensive daily routine in an astronomers life.
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Links: HDA (for tours) Scanproject@LSW Plate Archive |
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| Image of Bruce telescope | Scanned Schmidt Plate | Scanned Bruce Plate |
The aim of the diploma thesis was to analyze a subset of 182 of the 240 probable BL Lacertae candidates, found by Collinge et al. (2005), for variability. That task was accomplished by comparing the magnitudes of the stars in the field of view with magnitudes from the Sloan Digital Sky Survey (SDSS) in order to calibrate the flux and then compare the measured magnitudes of the BL Lac candidates to the ones measured by SDSS and testing them for variability. In spite of a conservative constraint at least ~59% (107/182) of the observed objects were found to be variable. Despite own data a cross-match of the infrared all sky surveys UKIDSS (UKIRT Infrared Deep Sky Survey) and 2MASS (Two Micron All Sky Survey) was performed with the result that 31/36 (~86%) of the objects observed in both surveys were variable. A cross-match of the different SDSS data releases led to another 9 out of 10 varying objects observed at least two times with SDSS.
In addition spectroscopic data were taken at Calar Alto in order to resolve spectroscopic features with the aim to determine the redshift for objects with unknown SDSS redshift. Even though the signal to noise ratio was higher (roughly by a factor of 2) than in the SDSS data most objects did not show any (new) features in our data either, i.e. 28 spectra were taken but only 1 secure redshift was determined.
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Publications: Poster for AG conference Publication in ApJ |
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| On the difference of LBL and HBL | Polarization and Variability distribution | Polarization and Variability against redshift |
One of the main reasons for low efficiencies when observing with Luci at the LBT is far from being perfect submitted phaseII-material. This is particularly true for the scripts which are used to execute the observations at the telescope itself. The LBT organization has developed a script checking tool, which, however, checks only if the scripts are formally correct. It does not complain if e.g. the guide star selected for an observing setup is out of the patrol field. In order to largely circumvent the problems with badly designed scripts a HTML-based tool named "Scriptor" was developed. It allows a wide range of applications from creating individual scripts for acquisition, imaging, etc. but also to derive a full set of scripts for longslit or multi-object spectroscopy at once. One of its main features is the convenient selection of an appropriate guide star. It inculdes also a formal check of the newly created scripts. The "Scriptor" may serve in the future as a global platform for creating scripts for the majority of LBT instruments.
Presentation from AG conference can be found here.
This work is about direct imaging, and possible adjacent spectroscopy, of 12 objects, which are candidates for supermassive black hole binaries (BHB hereafter). Using available instruments at the Large Binocular Telescope with diffraction-limited mode, we can obtain images with a resolution of about 0.04'', which complies at redshift between 0.1 and 0.5 with a spatial scale of 80-240pc.
The search for BHB is a rather young astrophysical topic. That is why there are still rather few works, which are about the systematic search of such objects. Smith et al. (2010) and Tsalamtza et al. (2011) haven mined the spectroscopic database of SDSS for objects, showing signatures of 2 binary AGN. Those can produce double-peaked narrow/broad lines if the binary distance is great/small. Those candidates are the basic objects for our research.
For sub-kpc candidates from Smith et al. (2010) we can probably resolve the individual components. With that we can probably solve the origin of the double-peaked forbidden [OIII] lines and verify candidates.
For the objects from Tsalmantza et al. (2011) we won't be able to resolve the objects spatially, but the imaging of the inner part of the galaxy, will still give us some hint about the origin of the double-peaked broad lines.
Project summary (only german) can be found here.
My CV can be found here.
I am living in Heidelberg since october 2005, with 2 big breaks within. While my studies I went to Umea, North-Sweden where I studied Astrophysics as an ERASMUS student. Umea is probably the best city to live in - despite a lot of possibilities of doing sports/hiking, the university is packed with awesomely friendly and helpful stuff and students. Also Umea is called the capitol of veganism, which was very unexpected for me - up there north where nearly nothing eatable grows - well despite of cranberries of course. Furthermore, the visit up there brought back my fascination for physics which sometimes came out of sight - by listening to subjects, which I disliked. Next to my working inspiration I also found my today's wife Annika, which is working as a midwife in Ladenburg. After I finished my studies, I went with her for half a year to South America where we mainly visited all the different parts of Chile and partially Argentinia. That was another quite impressive trip with a lot of hiking and getting to know lots of interesting people.
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| Kungsleden (SWE) | Umea (SWE) | Göteborg (SWE) | Romanievi (FIN) | Vindeln (SWE) | Nowhere (SWE) |
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| Valparaiso (Chile) | El Chaiten (Chile) | El Chaiten (Chile) | Valparaiso (Chile) | Torres del Paine (Ch) | Godson Uwe |