Extragalactic Astrophysics
Extragalactic astrophysics studies the galaxies and the space in between galaxies beyond our own galaxy, the Milky Way.
Large surveys have shown that the distribution of galaxies in the universe is far from random, but rather forms a cosmic web, composed of filaments of clustered galaxies stretched out across the universe and separated by giant voids. Astronomers aim to understand how and when these galaxies first began to form, how they grow and evolve with cosmic time, building up larger and larger structures.
Some of the key open questions in extragalactic astrophysics are:
- How do the first galaxies form and evolve throughout cosmic time?
- How and when do the most massive structures and galaxy clusters in our universe assemble?
- How do supermassive black holes form and influence the evolution of their host galaxies?
- How do supermassive black holes accrete gas from their environment and regulate galaxy growth?
Astronomers at MKI are using multi-wavelengths observations, ranging from radio to X-ray data, combined with cosmological simulations and machine learning models to answer these questions. They use both space-based and ground-based telescopes. In particular, they carry out observations with the Magellan Telescopes, two 6.5m optical telescopes located in the Atacama desert in Chile, as well as many space-based observatories, such as Chandra, HST or the recently launched JWST.
Extragalactic astrophysics at all wavelengths
Prof. Mike McDonald’s research group tackles a wide variety of astrophysical problems, with galaxy clusters serving as the most common (but not exclusive) backdrop for these studies. The hallmarks of their research include: i) the study of both nearby and the distant galaxy clusters, to track the evolution of these massive structures and their member galaxies, and ii) the use of multi-wavelength data from a variety of ground- and space-based telescopes to probe a variety of physical processes.
Cosmic Dawn
Astronomers observe supermassive black holes with billions of solar masses in size already at the very beginning of our universe, which poses a significant challenge to our understanding of galaxy and structure formation. Prof. Christina Eilers’ research group aims to understand how black holes form and grow by using a combination of multi-wavelength observations, as well as numerical and machine learning models to study their evolution and interplay with galaxies in the early Universe, during an epoch known as the Cosmic Dawn. They aim to understand how the first galaxies, quasars, and supermassive black holes came into existence and evolved across cosmic time to form the large-scale structure that is observed in the universe today.
Extragalactic transients
Recent time-domain surveys reveal transient accretion phenomena that defy all predictions. We witness stars torn apart by black holes (known as Tidal Disruption Events) and Active Galactic Nuclei that accrete material much faster than disk theory predicts. Professor Erin Kara's group works with time-domain surveys across the EM spectrum to find new transients and follow them up, largely in the X-ray band, with instruments like NICER, XMM-Newton, and XRISM. These supermassive black hole transients are giving us deeper understanding into how AGN are fed, and how quickly black holes can grow.