Research Highlights

GPU-powered real-time rendering in Python

The following videos feature recent developments of a GPU-powered rendering library that I developed for real-time rendering. I implemented the library in C++. Currently, I have bindings for Python and soon for Julia.

Its key features include dynamic loading of particle data using multithreading, the ability to define keyframes for making smooth and professional-looking movies, support for Xbox/PS4/PS5 Joystick inputs, and interactive selection of regions for analysis, etc.

This tool, whose working name at the moment is CosmoVR, will soon include advanced VR capabilities, making it ideal for both research and outreach events.

The first public appearance of CosmoVR during the Bicocca Astrophysics Day, both using a PS4 Joystick, and an Oculus Quest 2 Virtual Reality headset.

The video below features the interactive use of CosmoVR by the rector of the University, professor Giovanna Iannantuoni.

Reionization-Limited-HI-Clouds (RELHICs)

Benitez-Llambay et al. (2017)

RELHICs are a class of dark matter halos that do not contain a luminous galaxy in their centre, and whose existence and properties were predicted in my seminal paper. The following video highlights the main properties of RELHICs as observed in a high-resolution cosmological simulation, namely the location of RELHICs in the context of our Local Group, their gas content, and their HI and HII content, two potential observables.

The vertical structure of gaseous galaxy discs in Cold Dark Matter haloes

Benitez-Llambay et al. (2018)

The vertical structure of centrifugally-supported gaseous discs is a classic astrophysical problem with applications that range from protostellar and protoplanetary discs to spiral galaxies. Their physics is well understood: gas discs are systems that result from energetic losses and the conservation of angular momentum and whose vertical structure is determined by the balance between the gas pressure and the vertical force of gravity.

From a physics perspective, the equilibrium of a disc can be affected by different mechanisms, both internal or external to the disc. For example, a galaxy disc may be disturbed by accretion events or interactions with nearby galaxies. Also, stars may be able to form inside the disc and affect its stability and structure.

From a numerical perspective -and in the context of cosmological numerical simulations- the modelling of stable and long-lived gaseous (and stellar) discs have proven challenging. It was not until the development of the recent generation of simulations that astronomers were able to simulate realistic and nice-looking disc galaxies. However, numerical modelling carries its difficulties. Just to give an example, the limited mass and spatial resolution of numerical simulations (computers have limited memory and precision), can introduce spurious artefacts that preclude direct comparisons with reality, or even worse, confuse scientists that do not take them into account carefully.

In this paper, I stepped back and analysed the classic problem of studying the vertical structure of centrifugally-supported polytropic gaseous discs. This work is a generalization of a classic work carried out by P. Goldreich and D. Lynden-Bell back in the 1960s. I construct a framework to determine the vertical structure and stability of a gaseous polytropic disc embedded in a dark matter halo, and I also consider the impact of the limited spatial resolution of numerical simulations. My theoretical results can be used to benchmark numerical codes that intend to resolve and study the vertical structure of gaseous discs.

The panel below shows the scale height of an isothermal (polytropic index = 1) exponential gaseous disc within a dark matter halo (white solid line). The orange and blue dashed lines show the scale height for a non-self-gravitating and a self-gravitating disc, respectively. As I demonstrate in my paper , the scaleheight is simply the harmonic mean of the two. Note that you can input your values on the right panel and see how the scale height changes accordingly. The relevant parameters for this example are the dark matter total mass, its concentration, the exponential disc total mass, its effective radius, and the temperature of the gas. The default values are close to the values of the halo and stellar disc of our galaxy, the Milky Way.