[Okc-wp4] EO meeting: 10th of February

[Davide Gizzi]

Dear all,


a kind reminder of today's EO meeting.


Kind regards

________________________________
From: Davide Gizzi
Sent: Thursday, February 3, 2022 10:27:11 AM
To: Okc-wp4 at fysik.su.se; people at nordita.org
Cc: Quentin Perceval Xavier Pognan
Subject: EO meeting: 10th of February

Dear all,

our next EO meeting will take place on Thursday, 10th of February, at 13:15 (CET).
The speaker is Quentin Pognan, PhD student of Anders Jerkstrand (Stockholm University), working on light curves and spectra of kilonovae. He is going to talk about his recent work on this topic.

To join the meeting:
https://stockholmuniversity.zoom.us/j/65883589027?pwd=RGxJOUVQWmNtMlZFMUIwaHRabkExdz09

Meeting ID: 658 8358 9027



Below is title and abstract of the talk.

Title: The validity of the LTE and steady-state approximations for nebular phase kilonovae

Abstract:
Kilonovae (KN) following a binary neutron star merger are expected to enter a non-local thermodynamic equilibrium (NLTE) regime several days after merger, as ejecta densities rapidly fall. Accompanying this transition away from local thermodynamic equilibrium (LTE), is a transition to a ‘nebular’ phase, where spectra are dominated by emission lines, as opposed to scattering lines over a quasi-blackbody continuum. The nebular phase is initially in a ‘steady-state’ regime, until thermal reprocessing timescales become long, at which point the temperature and ionization states need to be evolved time-dependently. Since nebular phase spectra offer a possibility of element identification in KN, it is interesting to study the onset and significance of time-dependent effects. I will present a study into these effects conducted using the spectral synthesis code SUMO, and demonstrate that time-dependent calculations may be necessary for certain ejecta parameters. I will also briefly present some ongoing work on the importance of NLTE calculations for post-peak KN, with a focus on consequences for expansion opacities.


Hope to see you there!

Ana Sagués Carracedo & Davide Gizzi



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