[Doctorandos] Charla del Dr. A. Cikota : martes 31/5 a las 14 en el Salón Meridiano

[secyt en fcaglp.fcaglp.unlp.edu.ar]

Estimadas/os colegas,

la semana que viene estará de visita en La Plata el Dr.  Aleksandar  
Cikota del European Southern Observatory, Chile. El día martes 31 de  
mayo dará una charla sobre su tema de investigación, por lo cual  
los/as invitamos a asistir en modo presencial. La misma tendrá lugar  
en el Salón Meridiano de la FCAG, y se deberá mantener un aforo del  
50%, y el uso de barbijo. La charla será dada en inglés. Abajo  
encontrarán el título y resumen.

Les dejo además el contacto de Aleksandar (aleksandar.cikota en eso.org)  
y de Natalia por cualquier duda o consulta  
(natalialrossignoli en gmail.com). Quedan todos/as invitados/as.


Dr. Favio R. Faifer
Director
Instituto de Astrofísica de La Plata
CONICET-UNLP

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Investigating Type Ia Supernovae with (spectro)polarimetry

Abstract: Spectropolarimetry offers an independent method to the study  
inter/circum-stellar dust properties (by observing the continuum  
polarization) and the analysis of the three-dimensional geometrical  
properties of unresolved sources (by observing the intrinsic continuum  
polarization and line polarization).
I will discuss the results from a statistical analysis of the Si II  
line polarization measurements of a sample of ~35 SNe Ia, and argue  
possible implications on the progenitor system. We reduced and  
examined, in a systematic way, archival linear spectropolarimetric  
data of a sample of 35 SNe Ia observed with the VLT’s FORS1+2 between  
2001 and 2015 at 127 epochs in total (Cikota et al. 2019).
We found a statistically significant linear relationship between the  
polarization of the Si II 6355Å line before maximum brightness and the  
Si II line velocity and suggest that this, along with the Dm15–PSi II  
relationship, may be explained in the context of a delayed-detonation  
model. In contrast, we compared our observations to numerical  
predictions in the Dm15–vSi II plane and found a dichotomy in the  
polarization properties between Chandrasekhar and sub-Chandrasekhar  
mass explosions, which supports the possibility of two distinct  
explosion mechanisms.
Furthermore, we acquired imaging polarimetry of a statistical sample  
of 68 SNe Ia in host galaxies of different morphological types, and  
found that the source of the peculiar polarization curves steeply  
rising towards blue wavelengths (and the peculiar extinction curves  
with low Rv values) observed towards some reddened SNe Ia is likely  
the result of interstellar material as opposed to circumstellar  
material. Thus, the peculiar polarization and extinction properties  
observed toward some SNe Ia may be explained by the radiative torque  
disruption mechanism induced by the SN or the interstellar radiation  
field (Chu et al. 2022).

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