Astronomy & Astrophysics
using multiwavelength data
Rainbow over the Anglo-Australian Telescope in Siding Spring Observatory, NSW, Australia © Á.R.L-S.
IC 10 is the nearest starburst. Our 2D spectroscopical analysis using PMAS @ 3.5m CAHA suggests the existence of a probable localized chemical pollution of nitrogen and helium from the fresh material released by a single Wolf-Rayet star. © Á.R.L-S., Adel Mesa-Delgado, Luis López-Martín & César Esteban
The new observational technique of 2D spectroscopy using Integrated Field Units (IFU) is providing amazing new results about the kinematics and the chemical composition of galaxies. In particular, Blue Compact Dwarf Galaxies (BCDG) are excellent targets to perform such studies, because their modest sizes allow that all the galaxy can be observed in just some few pointings. During the last years we have collected some 2D spectroscopy data of a sample of BCDG using both the WiFeS instrument available at the 2.3m ANU telescope at Siding Spring Observatory and the SPIRAL instrument available at the 3.9m Anglo-Australian Telescope, also at Siding Spring Observatory. The preliminary analysis of these data are quite promising. We are offering the opportunity of study a sample of several BCDG for which we already have good-quality data, as well as continue our observations of BCDG at these (WiFeS at 2.3m ANU and new instrument KOALA at 3.9m AAT) or other optical telescopes (GEMINI, VLT, WHT, CAHA). In particular, this project will give the student a detailed understanding of the 2D spectroscopy techniques. The student will then gain expertise in the reduction and analysis of this kind of data. The aims of this project are to perform a detailed analysis of the physical (mass, star-formation rate, extinction, electron temperature and density, excitation), chemical (ionic and total abundances of helium, oxygen, nitrogen, sulphur, neon, argon...) and kinematical (rotation of the galaxy, distortions due to interactions, existence of outflows or inflows of gas) properties of the ionized gas within these galaxies. The analysis of the stellar component underlying the strong starbursts can be also studies. Hence, we will compare the properties of the stars and the ionized gas with the properties of the neutral gas (derived using our own ATCA observations). Finally, the student will also learn to write up the results not only for his/her Thesis but for subsequent publications. As an example of this project, please consult the 2D spectroscopical analysis of the brightest star-forming region of the local BCDG IC 10, López-Sánchez et al. (2011), this research image, and the combined optical-radio study of the BCDG NGC 5253, López-Sánchez et al. (2012).
Near-infrared (NIR) observations at 1.65 microns (H-band) traces the old stellar population (and hence, the dominant stellar mass distribution) of galaxies, while dust attenuation is dramatically reduced. Although 2MASS surveys the entire sky, it failed to detect almost all dwarf systems and underestimates the fluxes of those it did detect by as much as 70% (Kirby et al. 2008). We are obtaining very deep H-band observations of local dwarf galaxies using the instrument IRIS2 at the 3.9m AAT at the Siding Spring Observatory. The target galaxies belong to the The Local Volume HI Survey (LVHIS), and hence we already know their neutral gas distribution, as well as many other multi-wavelength properties. The aim of this Honour project is to reduce and analyse the H-band images of a sub-sample of these galaxies. Many of the observations will be carried out in the next months, and hence the student will have the possibility of participate in them. This project will give to the student a very good knowledge of NIR observations. Using the new images, the candidate will be able to derive the Sersic parameters that best describe the observed surface brightness profiles of the galaxies, as well as estimate their stellar masses from their absolute H-band luminosity. The derived stellar mass will be compared with the total neutral gas mass and the dynamical mass derived from the HI observations, as well as with other properties such as the extinction, the metallicity, or the star-formation rate, to constrain the nature and evolution of each galaxy. Comparing the new results with those already available, the student will also analyze the classical (using the B-band absolute magnitude) and the baryonic (stellar plus gas masses) Tully-Fisher relations. This study will provide powerful constraints to the nature and evolution of dwarf galaxies. Finally, the student will also learn to write up the results not only for his/her Thesis but for a subsequent publication.
This project is now the PhD Thesis by Tye Young (RSAA/ANU).
Other interesting projects I have in mind are these:
| Updated: 07.07.2013 | Released: 25.01.2011 |