Jarkko Laine

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.

Word cloud created with https://scimeter.org/clouds/


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.

Illustration of a small galaxy group in the GAMA survey. Image credit: GAMA survey.

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.

Examples of disk breaks in two S4G galaxies. Image from Laine et al. 2016.

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.

Examples of a bulge-disk-bar decomposition. Image from Salo et al. 2015.


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:


Below is my abriged professional history. Send me an email if you want to know more!




Mar. 2020

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
Aug. 2017
Jan. 2020

Postdoctoral researcher

Examining the environmental properties of galaxies using the GAMA survey.
Supervisor: Prof. Jochen Liske
Hamburg Sternwarte,
Universität Hamburg, Germany
Nov. 2016
May 2017

Postdoctoral researcher

Developing a 2D photometric decomposition pipeline for the MaNGA survey.
Supervisors: Prof. Vladimir Avila-Reese, Dr. Héctor Hernández Toledo
Instituto de Astronomía,
UNAM, Mexico
Apr. 2011
Oct. 2016

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