Hi there! I'm a former astronomer (PhD.), and current data science and artificial intelligence Masters degree student at the University of oulu
in Finland. Unfortunately, this homepage introduces my previous career, and I've not updated it to reflect my current path. Maybe some day I will,
but at the moment this is more of a placeholder. Feel free to explore anyway!
Before my transition away from academic career I was apostdoctoral researcher at the Hamburg Sternwarte in Germany. My research focused on exploring what are the physical processes responsible for the observed properties of galaxies in the nearby Universe. I used resolved optical and infrared imaging data to examine galaxies and their different structural components in detail, and redshift surveys to trace the galaxies environments. The word cloud below illustrates the most relevant topics of my astronomy research.
GAMA - Galaxy And Mass Assembly
In Hamburg I worked Prof. Joe Liske on the GAMA survey. Our aim is to examine the importance of environment on galaxy evolution by looking in which environments galaxy pairs and mergers are most commonly found. If a preferred location is found, this would point to a location where galaxies are pre-processed by mergers, before they are accreted to more dense environments following the hierarchical structure formation of the Universe.
The Spitzer Survey of Stellar Structure in Galaxies (S4G)
My PhD. studies revolved around the Spitzer Survey of Stellar Structure in Galaxies project, in which 2300 nearby (< 40 Mpc) galaxies of all morphological types were observed in 3.6 and 4.5 micron wavelengths using the Spitzer Space Telescope. Full description of the survey can be found in Sheth et al. 2011. This survey has expanded significantly since the first data release in 2015 (@ NASA/IPAC archive), and more massive early-type as well as low mass galaxies of all types are being added to the sample using Spitzer Space Telescope and various ground-based optical telescopes. I am member of the core data team of this survey, and below I introduce some of the key areas of the survey I was part of.
Disk breaks in S4G
The surface brightness in galaxies disks is generally assumed to follow a simple exponential decline. However, it has been found that this does not apply for
most disk galaxies, and instead multiple exponential sections are found in the disks (see examples below). These changes between exponential sections are called
disk breaks, and they are thought to be formed by multitude of internal processes of galaxies, as well as galaxies environmentally driven processe.
In two of my papers (Laine et al. 2014 and Laine et al. 2016) I examined these disk breaks using S4G data with samples of hundreds of galaxies. The main results of these two studies were the connection of disk breaks with the morphological structures of the galaxies. For example, we found a connection between ring structures and down-bending Type II breaks: the rings are formed due to bar resonances in the disks by accumulating gas at the resonance radius, and the resulting star formation eventually manifests as a change in the disk surface brightness profile.
Multicomponent photometric structural decompositions
My major contribution to the data analysis pipelines of the S4G survey was in the two dimensional multicomponent photometric structural decomposition pipeline. In this work we made human supervised decompositions of all the 2300 galaxies of the first phase of the survey, which decompositions include, when judged appropriate, a central point source, bulge, disk, and bar components. This work is explained in detail in Salo et al. 2015, and the decomposition sample remains to be the largest galaxy sample for which such detailled decompositions have been made. Decompositions of the extended S4G survey sample, as well as detailed analysis of the galaxy bulge, disk, and bar parameters are underway.
Full up to date publication list can be found at the SAO/NASA ADS. Articles I've been part of have been cited a total of 1290 times and my h-index is 20 (June 2018).
Below is a few picks from my publications:
- Influence of galaxy stellar mass and observed wavelength on disc breaks in S4G, NIRS0S, and SDSS data
Jarkko Laine, Eija Laurikainen, and Heikki Salo
Astronomy & Astrophysics, 2016
You can also access additional online material of this article through this link.
- The Spitzer Survey of Stellar Structure in Galaxies (S4G): Multi-component Decomposition Strategies and Data Release
Heikki Salo, Eija Laurikainen, Jarkko Laine et al.
The Astrophysical Journal Supplement Series, 2015
- Morphology and environment of galaxies with disc breaks in the S4G and NIRS0S
Jarkko Laine et al.
Monthly Notices of the Royal Astronomical Society, 2014
Below is my abriged professional history. Send me an email if you want to know more!
Data science and AI Masters degree student
Career shift towards industry and private sector by building on top of my previous knowledge with additional studies on data science, sensor/data fusion, machine learning, statistics, signal processing, ...
|Computer Science and Engineering,
University of Oulu, Finland
Examining the environmental properties of galaxies using the GAMA survey.
Supervisor: Prof. Jochen Liske
Universität Hamburg, Germany
Developing a 2D photometric decomposition pipeline for the MaNGA survey.
Supervisors: Prof. Vladimir Avila-Reese, Dr. Héctor Hernández Toledo
|Instituto de Astronomía,
PhD in Astronomy
Thesis title: Understanding the formation and evolution of disc break features in galaxies
Supervisors: Docent Eija Laurikainen, Prof. Heikki Salo
| Department of Physics,
University of Oulu, Finland