Link to publications on ADS

Mergers in cosmological simulations

Most of the existing literature about major merger simulations relies on idealized setups, where equilibrium galaxies are initialized on Keplerian orbits. In Sparre & Springel 2016 we have for the first time studied a sample of several major mergers in full cosmological setups. We show that strong nuclear starbursts (which strongly resemble e.g. ULIRGs) occur when mergers are colliding head-on in high-speed orbits. In future work we will study the morphological evolution of the stellar disks of the merging galaxies.


The z=0 stellar components of the remnant of the four major mergers. In addition to a red bulge, the galaxies have a disk mainly consisting of stars formed after the merger.

Star formation in galaxy simulations

I work on star formation in galaxy formation simulations. Of special interest to me is the star formation rate – stellar mass relation of observed galaxies, which I have studied in the Illustris simulation ( and in FIRE (

SFR-variability in FIRE

At low masses (stellar mass below 10^(9.5) solar masses) there is a large amount of SFR-variability in FIRE. This figure shows the 10-Myr-averaged SFRs in 20 non-overlapping within a 200 Myr period. In an observational paper Guo et al. 2016 found evidence for a similar amount of bursty star formation.

Star formation histories

Average and median star formation histories for galaxies in different stellar mass bins in Illustris. More-massive galaxies form their stars earlier than low-mass galaxies.

Gamma-ray bursts

Gamma-ray bursts are the most violent explosions in the universe, where a collapsing star in a few seconds emits the same amount of energy as the sun emits in its entire lifetime. I am involved in an observational program, where we observe gamma-ray bursts with the X-shooter spectrograph mounted at the Very Large Telescope at Paranal in Chile.


The four 8.2 meter telescopes at Paranal Observatory.

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