Measuring the Hubble Constant with Moving Standard Siren
组织者
时间
2025年02月28日 16:00 至 17:00
地点
A3-2-301
线上
Zoom 787 662 9899
(BIMSA)
摘要
The Hubble Tension, describing the diasgreement between measurements of the Hubble Constant in the early and local universe, is one of the biggest problems in modern cosmology. Using gravitational wave detections with an electromagnetic (EM) counterpart, so-called standard sirens, we will be able to measure the Hubble Constant from low to high cosmological red shifts. Therefore, there is great hope that standard sirens will help reolve the Hubble tension. One promising type of standard sirens are binary black holes (BBHs) in active galactic nuclei (AGNs). However, most current studies do not treat consistently the effects the AGN disk can have on the BBH and, in particular, on the meausrement of the Hubble Constant. In this talk, I focus on the effect the induced motion of the BBH has on the measurement of the Hubble Constant. Furthermore, I present a (re)analysis of GW190521 with its EM counterpart including this effect as well as others to obtain improved estimates of the Hubble Constant.
演讲者介绍
Alejandro Torres Orjuela obtained his Physics Bachelor's degree from the Free University of Berlin (Germany) and his Physics Master's degree as well as his Bachelor's and Master's degree in Mathematics from the Technical University of Berlin (Germany). Later, he moved to China to do his Ph.D. in Astrophysics at Peking University where he worked with Prof. Xian Chen and Prof. Pau Amaro Seoane from 2017 to 2021. After his Ph.D., Alejandro moved to the TianQin Center at Sun Yat-Sen University in Zhuhai (China) where he worked for two years as a PostDoc in the Theoretical Study group led by Prof. Jianwei Mei. In 2023 and 2024 Alejandro took a position as a Post-Doctoral Fellow at the University of Hong Kong where he was part of Prof. Lixin Jane Dai's group. In November 2024 Alejandro joined BIMSA as an Assistant Professor in the "Mathematical Physics and General Relativity" group. Alejandro works on different aspects of gravitational wave astronomy with a particular focus on the effect of the environment on gravitational wave detection with two major goals: understanding how environmental effects impact - and potential bias - detection and how these effects can be used to study the environment of the source. His research further includes gravitational wave sources with electromagnetic counterparts and their use as standard sirens to measure the expansion of the universe. Alejandro's studies involve different kinds of gravitational wave detectors across the spectrum with a particular focus on space-based detectors TianQin and LISA in the mHz band, atom interferometry detectors in the dHz band, and kHz detectors LIGO-Virgo-KAGRA.