UA-56497231-1

For the past years I have been doing the following projects:
  • Tidal disruption events of stars by single and binary SMBHs.
A tidal disruption event occurs when a star gets sufficiently close to a supermassive black hole and is pulled apart by the tidal forces. It has been proposed the appearance of flares produced by these events, and the posterior decay of the light curve are sensitive to whether the star is partially or totally destroyed by the tidal field, but the physics of the disruption and later fall-back of the debris are still poorly understood. For the first time, we are modelling the hydrodynamical evolution of solar-type stars as they approach a SMBH using the state-of-the-art moving-mesh code AREPO. By mapping the results of the one-dimensional stellar evolution code MESA instead of the polytropic profile often used in the literature, we are able to have a much more realistic representation of the star. Additionally, AREPO provides an unique opportunity to study these events with unprecedented accuracy, since it comprises the advantages of both SPH and grid codes, without most of their limitations. For example, it can follow very precisely the orbits around the black holes since it conserves angular momentum, and it can resolve shocks in the debris as it falls back and self-interact.

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In the figure above we can see the evolution of a 1 solar mass zero-age-main-sequence star as it interacts with a 1 million solar masses black hole. During this very deep encounter, where the periapsis distance is well within the tidal radius of the SMBH, we observe how the star is streched, and then completely disrupted by the gravitational forces.
  • Hydrodynamical simulations of infalling clouds onto sub-parsec massive black hole binaries.
I am using a modified version of the SPH code GADGET-3 to model numerically the interaction between molecular clouds and SMBHs. I study the formation and dynamics of discs around the binary depending on the different orbital configurations for the clouds, as well as the dynamical evolution of the binary orbit.

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In the figure above we observe the formation of the so-called mini-discs around each black hole due to the near-radial infall of a cloud. The co-rotating interaction between the binary and the gaseous material is characterized by a strong slignshot, giving rise to a very eccentric tail of gas.

  • Modeling of AGN feedback on a semi-analytic model of galaxy formation.
I am part of the SAG (Semi-Analytical Galaxies) group, lead by Sofía Cora and Nelson Padilla, which developed a semi-analytic code for formation and evolution of galaxies within a cosmological context. My research with them is trying to find a more physical description for the AGN luminosity and feedback. I implemented a model for the BH magnetosphere that invokes the magnetic coupling between the closed magnetic field lines and the accretion disc, making the luminosity of this disc extremely dependent on the BH spin. With this model we are able to relate the evolutionary history of the galaxies and the amount of gas reheated by the BH.

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In the figure we see the axisymmetric magnetic lines of the model, where the closed ones go through the accretion disc and the open ones go to infinity producing a jet.
  • Analysis of mock galaxy catalogues from simulations.
In a summer research project, I used a galaxy catalogue produced with the Millennium cosmological simulation and the semi-analytic model of Bower et al. (2006), to calibrate measurements of galaxy group masses. I created a mock catalogue to mimic the observations of 6 galaxy groups from the CFHTLS Strong Lensing Legacy Survey. In particular we were interested on the accuracy of the gapper mass estimator.

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In the figure above we see the ratio of the mass using the gapper method and the value extracted from the simualtion as a function of the galaxy members, for two different limits in magnitud.