Collection of my writings & publications

Arcmancer: general purpose ray tracer

In the project led by Pauli Pihajoki, we took ray tracing and numerical differential geometry to the next level. Images of black holes, disks, neutron stars? Can do!

Helium composition in 4U 1820-303

In the work led by Valery Suleimanov, we applied the direct cooling tail method to constrain the atmosphere composition of a neutron star in 1820. Our results show that helium is strongly favored.

Variable spreading layers of neutron stars

In the work led by Jari Kajava, we studied the interface between the neutron star and the accretion disk. This so-called spreading layer seemed not as constant as people have previously assumed!

Dynamic powerlaw method for X-ray bursts

How do X-ray bursts really cool? Is it a single-index powerlaw or maybe an exponential? We investigated this together with our student Jere Kuuttila.

Direct cooling tail method

Here we derived some corrections to our existing cooling tail method. This new method is then applied to a previously measured neutron star, identifying about 500 meter calibration error.

Traces of heavy metals in neutron star atmospheres

Some peculiar X-ray bursts are found to have atmospheres that are made almost completely of heavy metals. A radiatively driven wind might then ejects some of the burning ashes into the interstellar space.

Equation of state of dense matter from X-ray bursts

Equation of state of the cold dense matter has remained mystery for decades. In this recent work, we set new constraints to the EoS parameters by using X-ray bursts that show signs of passive cooling.

Heavy metal neutron star atmospheres

What happens to the observed spectrum of neutrons stars when the atmosphere is full of heavy metals from the nuclear burning? On this article, published in A&A we test the effects by computing detailed atmosphere models.