Seminario. Lorena Amaya Ruiz (Universidad de Sejong, Corea del Sur)

"QUOKKAS: Measuring cosmological distances using VLBI." 
Speaker: Lorena Amaya Ruiz 
(Universidad de Sejong, Corea del Sur) 

Abstract: 
Distance measurement remains one of the most fundamental yet 
challenging aspects of astronomy. While established methods like 
parallax, Type Ia supernovae, and Cepheid variables have helped 
transform astronomy into a precise physical science, astronomers 
continue to seek new standard candles and rulers. Very Long Baseline 
Interferometry (VLBI) is a powerful technique that combines radio 
telescopes across continents to achieve great angular resolution. 
Thanks to that, VLBI is a good technique for observing active galactic 
nuclei (AGN), which rank among the universe's most luminous objects 
and show promise as distance indicators. We present a novel method 
that combines radio flare observations in AGN jets with causality 
arguments to establish a standard ruler, which can be calibrated 
against apparent sizes measured through VLBI. This 'Causality 
Distance' method is currently being implemented in the Cosmological 
Quasar Observations on the KVN from Korea to Australia and South 
Africa (QUOKKAS) project, monitoring 50 AGN weekly across a redshift 
range of 0 < z < 5. To validate this approach, we analyzed archival 
data from MOJAVE (Monitoring Of Jets in Active Galactic Nuclei with 
VLBA Experiments), selecting 15 sources to determine their angular 
diameter distances using the Causality Distance method. 


Fecha: jueves, 30 de enero de 2025 
Hora: 12:10 horas 
Lugar: Seminario de Física Teórica