Academic qualifications

• Max-Planck-Institute for Astronomy (MPIA), Heidelberg, Germany
    PhD, Astronomy (2016 - Present)

Institute for Astrophysics, University of Vienna, Austria
    M.Sc., Astronomy (2013 - 2016)

Institute for Astrophysics, University of Vienna, Austria
    B.Sc., Astronomy (2010 - 2013)

A detailed CV can be found here.

Distribution of molecular gas in our Milky Way

In this ongoing project of my PhD, I try to use existing knowledge about the structure of our Milky Way to infer distances to the fitted emission line components from the Galactic Ring Survey (see project below). We use the Bayesian Distance Calculator tool (Reid et al. (2016)) to get distance solutions to the fitted components by folding in prior information, such as the rotation curve of our Milky Way, parallax measurements to high-mass star-forming regions, spiral arm positions determined from Galactic plane surveys, and distance solutions from the literature. This work will allow us to quantify the fraction of molecular gas located in spiral arms and to infer how important physical quantities change with Galactocentric distance.

Face-on view of the gas emission from the Galactic Ring survey overplotted with the spiral arm information from Reid et al. 2016. The two panels show preliminary distance results obtained with two different settings of the Bayesian Distance Calculator tool (Reid et al. 2016).

Decomposition of the Galactic Ring Survey

The main project of my PhD deals with the automated decomposition of the about 2.3 million 13CO spectra of the Galactic Ring Survey, a large Galactic Plane survey of the first quadrant of our Milky Way. For this work I developed a new fully automated decomposition package called GaussPy+ (see below). In a recent publication, we discuss global results of the gas emission obtained via the decomposition, including basic statistics of the fit parameters, a characterization of the complexity of the gas emission along the line of sight, and a discussion on how the fitting results can aid in disentangling gas emission coming from the near and far side of the Galactic disk.

GaussPy+ decomposition results of the Galactic Ring Survey. The upper panel shows emission from the original data set and the lower panel shows the emission recreated from the fit components.


As part of my PhD work, I have developed the fully automated Gaussian decomposition package GaussPy+. It is built upon the GaussPy algorithm, which uses derivative spectroscopy and a machine learning technique to automatically fit emission line spectra. GaussPy+ offers several improvements, including automating preparatory steps, an improved fitting routine, and a routine to refit spectra based on neighboring fit solutions to provide spatial coherence between the fit components. GaussPy+ is freely available and a detailed description about the algorithm can be found here.

Giant Dust Clouds in NGC 300

For my Master's thesis I analyzed dust emission observations from the Herschel Space Observatory of the nearby spiral galaxy NGC 300. I used a multiwavelength source extraction algorithm to compile a catalogue of giant dust clouds in NGC 300, including total mass and temperature estimates. I have also used archival data from the Galaxy Evolution Explorer, the MPG/ESO-2.2 m telescope, and the Hubble Space Telescope to characterize these objects across multiple wavelength regimes. This work resulted in a scientific publication that can be accessed here.

Map of NGC 300 at a wavelength of 350 µm overplotted with the catalogue of 146 identified Giant Dust Clouds (small black dashed ellipses). The colored circles indicate complementary pointed observations of molecular gas (blue: detection, yellow: marginal detection, red: non-detection).


Riener, M.; et al.; "Autonomous Gaussian decomposition of the Galactic Ring Survey. II. Distance estimates for fit components & distribution of the 13CO gas", in prep.

• Duarte-Cabral, A.; [...]; Riener, M.; et al.; "The SEDIGISM survey: Molecular clouds in the inner Galaxy", 2019, submitted to MNRAS.

Riener, M.; Kainulainen, J.; Beuther, H.; Henshaw, J. D.; Orkisz, J. H.; and Wang, Y.;, "Autonomous Gaussian decomposition of the Galactic Ring Survey. I. Global statistics and properties of the 13CO emission data", accepted by A&A

Riener, M.; Kainulainen, J.; Henshaw, J. D.; Orkisz, J. H.; Murray, C. E.; and Beuther, H.; "GaussPy+: A fully automated Gaussian decomposition package for emission line spectra", 2019, A&A, 628, A78.

• Henshaw, J. D.; [...]; Riener, M.; et al.; "`The Brick' is not a brick: a comprehensive study of the structure and dynamics of the central molecular zone cloud G0.253+0.016", 2019, MNRAS, 485.

Riener, M.; Faesi, C. M.; Forbrich, J.; and Lada, C. J.; "Gathering dust: A galaxy-wide study of dust emission from cloud complexes in NGC 300", 2018, A&A, 612, A81.

(Research) interests, skills, and more

A small collection of things I like to pursue in my limited free time.

  • Data Visualization

    One of the most important aspects in communicating science is a good visual representation of the obtained results. I love playing around with different visualization techniques (such as matplotlib, seaborn, and Glue) and I am always keen on acquiring new plotting skills.

  • Machine Learning

    I am very interested in pursuing machine learning techniques and trying to see how they can be applied to problems in my research. I am part of an initiative at the MPIA that aims at having weekly meetings to discuss and understand machine learning concepts.

  • Programming

    Nowadays almost an essential skill for any astrophysicist, I am always eager to learn new coding skills. I am proficient in Python and have also limited knowledge in other languages (CSS, HTML, Fortran).

  • Observations

    I will try to use any favourable combination of free time and good weather to observe amazing objects in our sky. Currently, my go-to instrument for casual observations is the KING telescope.

  • Palaeontology

    I have an avid interest in palaeontology and try to stay on top of recent exciting research results. Had astronomy not been such an attracting force, I would currently probably be digging for fossils in some desert.


riener [at]


Office 225 • Max-Planck-Institut für Astronomie • Königstuhl 17 • D-69117 Heidelberg • Germany