About

I am a Postdoctoral Fellow at the Institute of Physics of the Czech Academy of Sciences. Before that, I was an assistant researcher at the Center for Astrophysics and Cosmology and School of Science, University of Nova Gorica, Slovenia. In August 2023, I successfully defended my PhD thesis titled "Relativistic tidal disruptions of realistic stars by supermassive black holes", conducted under the supervision of Prof. Dr. Andreja Gomboc (University of Nova Gorica, Slovenia) and Asst. Prof. Dr. Clément Bonnerot (University of Birmingham, UK). Prior to this, I completed my Master's degree at the Faculty of Mathematics and Physics, University of Ljubljana, Slovenia. My main field of research is the tidal disruption of stars in the vicinity of massive black holes. In addition, I teach undergraduate-level astrophysics courses and regularly participate in outreach activities.

Recent publications

My research has led to the following recent publications. A full list of my publications can also be found here or on ADS there.

1. “Spin-induced offset stream self-crossing shocks in tidal disruption events” (ADS/ Astro-ph), Jankovič T., Bonnerot C., Gomboc A., 2023, submitted to MNRAS

2. “The Mass Fallback Rate of the Debris in Relativistic Stellar Tidal Disruption Events ” (ADS/ Astro-ph), Jankovič T., Gomboc A., 2023, ApJ, 946, 25

Research

My research focuses on the study of stellar tidal disruption events (TDEs), where a star is disrupted by the strong tidal forces of a supermassive black hole (SMBH). These events generate transient emissions that have been observed on numerous occasions, and the rate of detections is expected to increase even further with the aid of high-cadence observational facilities. The transient signal from TDEs provides a unique opportunity to study SMBHs, stellar dynamics in galactic nuclei, and to gain insights into accretion physics. To fully utilize TDEs as a tool for understanding astrophysical phenomena, it is essential to conduct more focused research on the dynamics of the stellar debris and the radiation it generates. This will provide a more comprehensive understanding of the observational signatures of TDEs, which can be used to make more accurate predictions about associated astrophysical processes.

Since 2019 I have mainly focused on two projects related to hydrodynamic simulations of TDEs with the smoothed-particle hydrodynamics code Phantom.

• Study of the outflow from the self-crossing region (Jankovič et al., 2023), a region where the part of the stream that has passed the pericenter collides with the still in-falling gas. This collision leads to a self-crossing shock, which can trigger accretion disc formation. If the black hole rotates, the additional Lense-Thirring precession induces an offset between these two colliding components, which can affect the outcome of the interaction. I studied the effect of the black hole’s spin by locally simulating collisions between two offset streams. I found that the geometry of the outflow becomes less spherical and more stream-like as the vertical offset increases, due to less energy being dissipated when the streams only partially collide. This effect may enhance the self-crossing shock luminosity due to a reduction of adiabatic losses, and cause significant variations of the efficiency at which X-ray radiation from the disc is reprocessed to the optical band depending on the viewing angle. These potentially observable features hold the promise of constraining the black hole spin from tidal disruption events.

  
  

• The mass fallback rate of the debris in relativistic disruptions of realistic stars (Jankovič & Gomboc, 2023). The debris fallback rate is the rate at which the bound debris returns to the proximity of the SMBH after the disruption, and is often assumed to be directly related to the observed light curve of TDEs. For this purpose, I simulated disruptions of realistic stars, constructed with the code MESA, for different stellar and orbital parameters, and calculated the fallback rate. By taking into account both the general relativity and realistic stellar structure this work is currently the most accurate study of the debris fallback rate.

Outreach

I regularly participate in events that involve delivering informative astrophysics lectures for the general public. A PDF containing information on these public lectures and interviews can be found here.

Selected public appearances

• Interview in DELO available here.
• Interview for ARS available here.