[Graduados] Recordatorio: Mañana 25/4 - Seminario FCAG -10:30h "Global Anisotropies of ΩΛ" - Dr. Alejandro Clocchiatti (Instituto de Astrofísica de la Pontificia Universidad Católica de Chile)

[Secretaría de Ciencia y Técnica]

Buenos días,

les recordamos que *mañana viernes 25 de abril a las 10:30h *se 
brindará, en el Salón Meridiano, el Seminario FCAG *"Global Anisotropies 
of Ω_Λ "*. El mismo estará a cargo del *Dr. Alejandro Clocchiatti 
(**Instituto de Astrofísica de la Pontificia Universidad Católica de 
Chile)*, profesor invitado por el Dr. Omar Bevenuto. A continuación, les 
dejamos el resumen y los datos de conexión para aquellos que no puedan 
acercarse al Salón Meridiano.

*Resumen: *An analysis of the cosmological parameter Ω_Λ  fitted to 
subsamples of the Pantheon+ Type Ia supernova sample spanning 
2/π/ steradians for a grid of 432 pole positions covering the whole sky 
reveals two large-scale asymmetries. One of them is closely aligned with 
the Galactic north–south direction and the other points approximately 
toward R.A. ∼217fdg5, decl. ∼−26fdg4, ∼50fdg9 from the cosmic microwave 
background dipole Apex. The signal-to-noise ratio (S/N) of the multiple 
Ω_Λ  measurements in these directions is 3.2 ≲S/N ≲8.4. The first 
asymmetry is puzzling and would indicate a systematic effect related 
with the distribution of Pantheon+ supernovae on the sky and, probably, 
how the correction for reddening in the Galaxy is calculated. The second 
one, which entails a 2.8-σtension between Ω_Λ  measured in opposite 
directions, bears strong implications on our interpretation of Ω_Λ  as 
dark energy: it is consistent with the prediction for tilted observers 
located in a Friedmann–Robertson–Walker universe who could measure an 
acceleration or a deceleration with a dipolar asymmetry, irrespective of 
what the universe as a whole is doing. In this case, Ω_Λ  would not be a 
physical entity, a real dark energy, but an apparent effect associated 
with the relativistic frame of reference transformation.

*_Datos de conexión:_*

**

-Sala personal de posgrado en fcaglp.unlp.edu.ar

**
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https://unlp.webex.com/meet/posgrado1 | 28704029699


A fin de reducir el uso de residuos plásticos, les solicitamos que se 
acerquen con sus propias tazas para el café. Aunque este seminario será 
en formato híbrido, esperamos contar con su presencia.* *

*Saludos, *

*SeCyT-FCAG*

-- 
Secretaría de Ciencia y Técnica
Facultad de Ciencias Astronómicas y Geofísicas
Horario de atención: lunes a viernes de 8hs a 15hs
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