Date: Tuesday 10-Sep-2024
Speaker: Dr. Reinhard Genzel (2020 Nobel Laureate in Physics-UCLA)
Title: "Experimental Studies of Black Holes: Status & Prospects"
More than a century ago, Albert Einstein presented his general theory of gravitation. One of the predictions of this theory is that not only particles and objects with mass, but also the quanta of light, photons, are tied to the curvature of space-time, and thus to gravity. There must be a critical mass density, above which photons cannot escape. These are black holes. It took 50 years before possible candidate objects were identified by observational astronomy. Another 50 years passed until we can finally present detailed and credible experimental evidence that black holes of 10 to 1010 times the mass of the sun exist in the universe. Three very different experimental techniques have enabled these critical experimental breakthroughs. It has become possible to investigate the space-time structure in the vicinity of the event horizons of black holes. I will summarize these interferometric techniques and discuss the spectacular recent improvements achieved with all three techniques. In conclusion, I will sketch where the path of exploration and inquiry may lead in the next decades.
Date: Wednesday 18-Sep-2024
Speaker: Dr. Ehud Behar (Technion)
Title: Science Highlights From the X-Ray Spectrometer on Board XRISM - The First Year
In September 2023, the XRISM satellite was launched from the Tanegashima Space Center in Japan. On board XRISM is a focal-plane calorimeter, built at NASA/GSFC, that features unprecedented spectral resolution and sensitivity in the hard X-ray band above 2 keV. The talk will present highlights from the first year of XRISM, which include new insights into winds of massive stars, spectral morphology in supernova remnants, super-Eddington winds from low-mass X-ray binaries, evidence for high-energy super-winds in galaxies, and the most powerful quasar wind ever detected. The talk will stress the unique capabilities of the new instrument to make these discoveries.
Date: Wednesday 25-Sep-2024
Speaker: Dr. Dan Scolnic (Duke University)
Title: Measurements of the Expansion Rate of the Universe and the Lingering Hubble Tension
The standard model of cosmology has passed every test over the last twenty years. Yet it remains unsatisfactory, with 95% of the universe being dark components, whose nature we did not understand. Now, there are possible 'cracks' in the model, as recent observations of the local expansion rate of the universe, parameterized by the Hubble constant, do not match predictions using data from the Cosmic Microwave Background and our standard model. This is the best end-to-end test of our cosmological model, and currently, we do not pass the test. I will discuss my team's Pantheon+SH0ES measurements on the local side, and review the numerous crosschecks and tests on our data and analysis. I will show new data from the James Webb Space Telescope and explain how it strengthens the current tension. Finally, I will talk about how the community is moving forward, with different probes of the early and late universe, and what new theoretical ideas show the most promise.
Date: Wednesday 02-Oct-2024
Speaker: Dr. Timothy Heckman (Johns Hopkins University)
Title: Feedback and the Evolution of Galaxies and Black Holes
I will summarize our current understanding of the processes that govern the formation and co-evolution of galaxies and their supermassive black holes (SMBH). I will pose several of the most fundamental shortcomings of our current understanding and then examine how they may be addressed by the effects of the feedback provided by massive stars and actively growing SMBH. My focus will be on what we have learned so far from observations of universe, near and far, and I will conclude by describing future prospects using a new generation of facilities. I will do my best to give a talk that minimizes jargon and stresses the basic underlying physical processes.
Date: Wednesday 09-Oct-2024
Speaker: Dr. Caue Sciascia Borlina (Purdue University)
Title: Understanding the Evolution of the Early Solar System through Palemagnetism of Meteorites
Magnetic records from meteorites and their components can provide important information about the evolution and architecture of the early solar system. That is because large-scale magnetic fields and gas are coupled in protoplanetary disks. In this talk, I will present how we can use micro-paleomagnetism to obtain magnetic records from 100 micron-sized meteoritic inclusions (i.e., calcium-aluminum-rich inclusions and chondrules) to obtain constraints on the evolution of the early solar system. I will discuss how (1) the magnetic records from calcium-aluminum-rich inclusions point to the presence of magnetized disk winds and/or stellar outbursts during the very beginning of the solar system and (2) the magnetic records from chondrules suggest the presence of a disk substructure a few million years later. These results provide information about mechanisms that drove mass and angular momentum during the protoplanetary disk phase of the solar system, and how chemical reservoirs were kept apart during that time. In turn, learning how our solar system evolved can help us understand how planetary systems form elsewhere.
Date: Wednesday 16-Oct-2024
Speaker: Dr. Malena Rice (Yale University)
Title: Insights from the Orbital Architectures of Planetary Systems
The current configurations of planetary systems each provide a snapshot in time, encoding fossilized clues about the prevalence and diversity of systems and evolutionary pathways. Orbital architectures, therefore, offer fundamental insights into the physical processes sculpting planetary systems at both the individual and population level. In this talk, I will describe recent advances in our understanding of the 3D orbital architectures of planetary systems, outlining both observational constraints and their theoretical implications. I will discuss how the dynamic relationship between stars, planets, and minor planets informs the underlying processes shaping diverse planetary systems, drawing from the interconnected subfields of exoplanet and solar system science.
Date: Wednesday 23-Oct-2024
Speaker: Dr. Jed McKinney (University of Texas)
Title: Into the Dark: The Role of Dust in Shaping Galaxy Evolution
Astrophysical dust makes up less than 1% of the mass in galaxies but plays a transformative role in shaping their evolution. My research focuses on dust both as a lens through which to chart galaxy evolution, and also as a key ingredient in multi-scale astrophysical processes. In this talk I will highlight recent observations using JWST and ALMA to uncover dust-obscured star-formation and growing supermassive black holes across cosmic history. I will present work using large extragalactic imaging surveys with JWST and other facilities, as well as more focused spectroscopic follow-up. Both approaches are needed to first build statistical samples of the most massive and active galaxies in the Universe, and then understand what makes them tick. Finally, I will comment on future far-infrared space telescope mission concepts that will delve further into the dusty Universe than ever before.
Date: Wednesday 30-Oct-2024
Speaker: Dr. Floor Broekgaarden (UC San Diego)
Title: Gravitational Wave Paleontology: a New Frontier to Explore the Formation, Lives, and Deaths of Massive Stars Across Cosmic Time
We are on the precipice of the Big Data gravitational-wave era. Pairs of stellar-mass black holes and neutron stars across our vast universe occasionally merge, unleashing bursts of gravitational waves that can now be detected here on Earth. Over the next few years, the population of detected mergers will rapidly increase from about a hundred today to millions of detections per year as new observing runs and next-generation detectors provide data with ever-increasing precision and to larger distances, pushing the reach of gravitational-wave astronomy to the edge of the observable universe! Most excitingly, this wealth of data will provide an unprecedented probe of the physics of black holes and neutron stars, and of the evolution of the binary massive stars that once formed them. This could open the new frontier of "gravitational-wave paleontology": studying massive stars and binary evolution from their "remnant" compact object mergers, with the goal of answering some of the biggest open questions in astrophysics today: How do these gravitational-wave sources form? What can we learn from them about the formation, lives, and explosive deaths of massive stars across cosmic time? How do these sources help to enrich the universe with heavy metals? In this talk, I will outline the main bottleneck in this field: the Progenitor Uncertainty Challenge I will discuss how my research group is leading efforts to identify, quantify, and eventually overcome this challenge with the aim to open the new frontier of gravitational-wave paleontology and make unprecedented discoveries about massive stars across cosmic time from gravitational waves, as well as from other upcoming multi-wavelength and multi-messenger observations.
Date: Wednesday 06-Nov-2024
Speaker: Dr. Esra Bulbul (MPE)
Title: Precision Cluster Cosmology and Astrophysics with the eROSITA All-Sky Survey
Galaxy clusters, representing the peaks in the cosmic density field, serve as an independent and powerful tool for investigating the evolution of cosmic structures. The strategic identification of these clusters through multi-wavelength surveys is essential for advancing our understanding of gravitational theory, general relativity, and cosmological models. A significant milestone was achieved with the successful launch of eROSITA in July 2019. The German-built eROSITA X-ray telescope, on board the Russian-German Spectrum-RG (SRG) mission, operates within the 0.2-8 keV range and has produced the largest ICM-detected catalogs of galaxy clusters and groups through its first All-Sky Survey. With over 10,000 confirmed clusters, the survey is pivotal in refining cosmological parameters when combined with the data from optical surveys like DESI Legacy, DES, HSC, and KIDS. These parameters are constrained at a percentage level through the evolution of the cluster mass function, representing a significant leap forward, exhibiting a 5-9 times improvement compared to previous cluster surveys. In this talk, I will outline the constraints on fundamental cosmological parameters, neutrino masses, and general relativity derived from the first eROSITA All-Sky Survey. Additionally, I will present eROSITA's significant detection of warm baryons within cosmic filaments identified by optical surveys and the implications for our understanding of AGN feedback in group-size haloes. I will summarize the value-added products made available to the science community by the eROSITA consortium's data release.
Date: Wednesday 13-Nov-2024
Speaker: Dr. Alice Shapley (UC Los Angeles)
Title: The JWST Revolution in Galaxy Formation: A Spectroscopic Perspective
Understanding the formation and evolution of galaxies remains one of the great challenges of modern cosmology. Rest-frame optical spectroscopy serves as a uniquely powerful tool for untangling many of the key processes in galaxy formation, including the nature of galaxies' stars, gas, and dust. We present a brief history of rest-optical spectroscopic probes of the galaxy formation process at high redshift, ranging from early ground-based attempts to the very latest results from the James Webb Space Telescope, which has revolutionized our ability to learn about the most distant galaxies in the universe. We focus in particular on questions related to the evolving enrichment and physical conditions in the interstellar medium of star-forming galaxies in the early universe, as these place critical constraints on the cycle of baryons through galaxies over cosmic time.
Date: Wednesday 20-Nov-2024
Speaker: NO COLLOQUIUM
Title:
Date: Wednesday 27-Nov-2024
Speaker: NO COLLOQUIUM
Title: Thanksgiving Break
Date: Wednesday 04-Dec-2024
Speaker: NO COLLOQUIUM
Title:
