[Okc-wp4] EO meeting 29th Sept. UNUSUAL ROOM

[Ana Sagués Carracedo]

Dear colleagues,

This is a reminder for our next EO meeting next Thursday 29th of September at 13:15 (CEST). The speaker is Federico Schianchi talking about his work on neutron stars mergers. He is visiting Evan's O'Connor's group during this week.

The meeting will be fully in person unless personal request. This time the meeting will take place at the commom area of the astronomy department in Albano Hus 3 Plan 4.

Following the title and the abstract:


Implementation of first-order multipolar radiation transport in Numerical Relativity code BAM

Numerical-relativistic simulations of binary neutron star mergers have a key role in Multimessenger Astronomy, e.g., for modeling gravitational and electromagnetic emissions connected to those events. For an accurate description of electromagnetic counterparts, one needs to know the properties of the matter ejected during and shortly after the merger. Inside this material, heavy elements are synthesized depending on the electron fraction of the outflowing matter. The radioactive decay of these elements produce an observable thermal emission that takes the name of Kilonova. All these phenomena are highly dependent on weak interactions between baryons and neutrinos.My work consists of implementing a code that tracks the propagation of such particles and their interaction with matter. It will be part of our Numerical Relativity code BAM. The aim is to get a more accurate estimate of the ejecta properties, mostly of the electron fraction. Recent studies revealed that neutrino emission/absorption also influences the mass and velocity of the ejected material.The scheme is based on a first-order multipolar (M1) transport equation. It consists of evolving the energy and momentum densities of neutrinos without solving a full and too expensive Boltzmann equation.The advantage of transport formalisms with respect to the Leakage scheme currently implemented in BAM is the possibility to take into account for the neutrinos to be reabsorbed by the fluid in another point of the simulation domain, with transfer of energy, momentum and lepton number. Due to the already high computational cost of binary neutron star merger simulations spectral transport schemes are not affordable. We have then to opt for a grey M1 scheme, i.e, we only evolve energy integrated quantities, loosing information on the neutrinos spectrum.Because of this reason the implementation of a more sophisticated scheme like a Monte Carlo transport would be important for the future.


Looking forward to see you all,

Kind regards,
Ana Sagués Carracedo & Haakon Andresen

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