Event Type: Astrophysics Colloquium

Compact objects are among the most inspiring and extreme objects in the Universe, allowing us to probe a range of astrophysical phenomena unattainable on Earth, while offering opportunities to bridge research areas and astrophysics communities. Even more than 50 years into their discovery, neutron stars in particular continue to fascinate and puzzle us. The highly

 I will review ongoing work aimed at understanding when and how the major structural components of our Galaxy came into place.  The H3 Survey is collecting high resolution spectra for 300,000 stars at high latitudes.  In combination with Gaia astrometry, these data are providing a detailed view of the phase space structure of our Galaxy.

M51-ULS1b, the first candidate planet in another galaxy, was discovered because it transited a bright X-ray source in the Whirlpool galaxy, M51.  Searches for other distant planets provide powerful reasons to study the short-time-scale behavior of X-ray sources. Equally important are other classes of short-duration events, including X-ray flares which may be due to either system

The discoveries of thousands of exoplanets have presented a number of puzzles about their properties and origins. Until recently, though, many of the assumptions made by planet formation models could not be examined directly. We have now entered an era where deep, high resolution images of protoplanetary disks at millimeter and infrared wavelengths are yielding a wealth of

With the recent successful launch of JWST, a new window into exoplanet atmospheres is now wide open. Early JWST observations of exoplanet hosting systems have already proven the power of this observatory to provide new and transformational insights into exoplanet atmospheres. Although JWST will provided us with unprecedented looks at exoplanets in the infrared, to

Galaxy growth is a slow but continuous process. The observed properties of galaxies suggest that accretion must continue to support star formation. However, direct observational evidence of gas flows into galaxies have been extremely hard to come by. One of the most promising regions in our search has been the disk-halo interface, where new data

Dwarf galaxies pose strong constraints to the Lambda Cold Dark Matter (LCDM) model, with several outstanding challenges still to be reconciled between theoretical models and observations. I will discuss some of these tensions, including the mapping between stellar mass and halo mass, dark matter cores, morphology of dwarfs and diversity of rotation curves. I will

We have learned that our universe seems to be composed of significant amounts of invisible matter called dark matter and an unexpected dark energy driving the universe’s accelerating expansion. In the last few decades, we have also uncovered large populations of new worlds called exoplanets orbiting the stars of our Galaxy. These discoveries represent just

The Southern Stellar Stream Spectroscopic Survey (S5) is an ongoing spectroscopic program that maps the newly discovered stellar streams with the fiber-fed AAOmega spectrograph on the Anglo-Australian Telescope (AAT). S5 is the first systematic program pursuing a complete census of known streams in the Southern Hemisphere, providing a uniquely powerful sample for understanding the building blocks of

The success of transit and RV surveys have shifted the exoplanet field from pure discovery to a combination of discovery, demographic analysis, and detailed characterization, especially for exoplanet atmospheres. However, even with nearly 5000 exoplanets known, we are still working to understand their origins and evolutionary mechanisms. Using data from NASA’s TESS and Kepler/K2 missions,

Accreting stellar-mass black holes in X-ray binary systems show X-ray variations over a broad range of time-scales, which are generated by mass-accretion fluctuations arising in the turbulent accretion flow.  The variability is noise-like, but with certain plausible assumptions, we can use it to map the emitting regions close to the black hole by studying the response of distinct spectral components: the blackbody-emitting accretion disk

In our LCDM paradigm, galaxies form and reside in dark matter halos. Establishing the (statistical) relation between galaxies and dark matter halos, the `Galaxy-Halo connection’, therefore gives important insight into galaxy formation, and also is a gateway to using the distribution of galaxies to constrain cosmological parameters. After a brief introduction to how clustering and

With the ever-growing role of software development and computer programming in astronomical research, our community is faced with many new challenges in nearly every aspect of our profession. In this talk, I first will describe the various types of software and the many different roles it plays in the research cycle. I will also describe

Already in the first 8 months of science operations, JWST has begun to routinely detect and characterize the physical properties of galaxies with greater fidelity and at greater distances than were ever possible before.  For example, in the JWST Advanced Deep Extragalactic Survey (JADES) we have not only identified numerous z > 10 galaxies, but we have

Nowadays, non-classical (fixed-quadrature „squeezed”) light is routinely used in second-generation interferometric gravitational wave detectors such as aLIGO and AdVirgo to increase their detection sensitivity, leading to some of the most exciting astrophysical discoveries of the past years. Beyond this well-known application example, squeezing is a quantum technique that can benefit precision metrology in many other

The Sun is the closest star to Earth and hence provides a unique opportunity to study numerous stellar phenomena in detail unprecedented to other stars. One such phenomena, which is a longstanding mystery, is coronal heating of low mass stars. The solar corona contains plasma in excess of 1 MK at all times, strong concentrations

A fundamental understanding of planetary histories and characteristics requires an empirical connection between planet formation and evolved planets—a long-sought goal of astrophysics. This connection is now increasingly possible due to simultaneous revolutions in the observations of protoplanetary disks and exoplanet atmospheres. A key step towards relating these observations of different evolutionary stages is to characterize

MSE is a massively multiplexed spectroscopic survey facility that will replace the Canada-France-Hawaii-Telescope in the coming decade. This 12-meter telescope, with its 1.5 square degree field-of-view, will observe 18,000 – 20,000 astronomical targets in every pointing from 360 nm through H-band at low/moderate resolution (R=3,000/7,000) and and 360-1000nm at high (R=30,000). A Piezo actuated fiber

The advent of Gaia and of large photometric and spectroscopic surveys is changing the landscape of white dwarf studies. These incredible new data sets, together with improved models, have enabled tackling some unsolved mysteries concerning white dwarfs as a population, as well as discovering extremely peculiar objects that challenge our understanding of white dwarf formation and

The recent discovery of high-energy astrophysical neutrinos has opened a new window to the Universe. Identifying the sources of these neutrinos is the main focus of the emerging field of neutrino astronomy. Combining neutrino data and electromagnetic measurements in a multi-messenger approach may lead us to the sources of the neutrinos and help to answer

When we look up at the night sky, we see a static universe. However, observational surveys have revealed that our universe is dynamic, with a myriad of transient events. One of the most captivating contributors to our transient universe are energetic and fast explosions called short gamma-ray bursts (SGRBs). Derived from the mergers of neutron

The Milky Way’s satellite dwarf galaxies are powerful probes of many important astrophysical processes. Their kinematics provide insights into galactic dynamics and the nature of dark matter, while their chemical compositions preserve a history of early galaxy formation and nucleosynthesis. Recently, all-sky astrometry from the Gaia satellite has enabled the discovery and characterization of dwarf

I will discuss line intensity mapping (LIM) and its applications for understanding cosmology and star-formation across cosmic time. I will focus on TIME, a mm-wavelength instrument designed to use LIM to probe the [CII] line at redshifts ~5-9 and the CO lines at redshifts ~0.5-2. The instrument is a grating spectrometer with transition edge sensors

In this presentation, we will explore how laboratory magnetized plasma can help us uncover key questions of space physics and space exploration, including spacecraft heat shield performance, energetic electron transport during geomagnetic storms, and origins of life on Earth. In each case, experiments were conducted in hot magnetized plasma at the DIII-D tokamak. First, we

Data-driven methods using a large variety of machine learning techniques have reshaped observational data analysis and data modelling in many fields of astrophysics in the last decade. However, despite their impressive performance, many of these methods struggle with issues of interpretability, selection biases, confounding factors, and ad hocness. In this talk, I will focus on

Since the dawn of x-ray astronomy 60 years ago, finding and studying active galaxies (accreting supermassive black holes) has been a prime area of study. I will briefly summarize the events of the last 5 decades focusing on my own research. Over the last decade a major change in our understanding of these objects have

The remarkable progress in cosmology over the last decades has been driven by the close interplay between theory and observations. Cosmological observations and galaxy dynamics have shown us that 84% of all matter in the universe is composed of dark matter, which is not accounted for by the Standard Model of particle physics. The properties

Astrophysical black holes are surrounded by accretion disks, jets, and coronae consisting of magnetized relativistic plasma. They produce observable high-energy radiation from nearby the event horizon and it is currently unclear how this emission is exactly produced. The radiation typically has a non-thermal component, implying a power-law distribution of emitting relativistic electrons. Magnetic reconnection and

To understand our origins, we must understand the role that interstellar dust plays in delivering heavy elements to planetary systems. This requires an understanding of the chemical composition, sizes and shapes of interstellar dust: astromineralogy. X-ray observations provide the most direct means for astromineralogy through the absorption signatures of dust imprinted in the spectra of

Millisecond pulsars, rapidly rotating neutron stars, emit narrow radio pulses that can be used for precision metrology, including the detection of low-frequency (nanohertz) gravitational waves (GWs) that alter propagation distances. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration members have built a Galaxy-scale detector for GWs by precisely timing a large number of

For the last half-century, relativistic outflows accompanying the final collapse of massive stars have predominantly been detected via high-energy emission, as long-duration gamma-ray bursts (GRBs). Yet, it has long been hypothesized that GRBs are the tip of the iceberg of relativistic stellar explosions, because the conditions required to produce and detect a GRB are contrived.

The detection of exoplanets and the detailed characterization of their interior core mass fractions, and atmospheric compositions has become a cornerstone of observational astronomy. So much so that the 2020 astrophysics decadal survey identified the construction of the recently named ‘Habitable Worlds Observatory’, a flagship to directly image ~25 Earth analog planets around nearby Sun-like

The Galactic atmosphere is as essential to setting the global conditions in the Milky Way as our planet’s atmosphere is for sustaining life on Earth. Dramatic, multiphase gas flows course through the disk-halo interface and into the more extended circumgalactic medium (CGM), redistributing the materials generated over billions of years of star formation. In this

 Pulsar timing arrays use observations of millisecond pulsars to detect nanohertz gravitational waves. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) Collaboration has recently released their 15-year data set containing observations of 68 millisecond pulsars. These data contain evidence for Hellings-Downs correlations, which are characteristic of a gravitational wave background. In this talk, I

The Imaging X-Ray Polarimetry Explorer (IXPE) is a joint US-Italian mission that enables highly sensitive polarimetry observations of bright galactic and extragalactic sources within the 2-8 keV X-ray band. In this talk, I will focus on the IXPE findings since its launch in 2021, particularly the outcomes derived from X-Ray Binaries featuring stellar mass black

In this colloquium, we delve into the dynamic phenomena exhibited by magnetars, from their rapid and intense bursts to their potential role as multimessenger sources. We will explore the latest observational and theoretical advancements that allow us to unravel the mysteries of these cosmic powerhouses. The discussion will extend to the necessity of future missions

Jets are a ubiquitous phenomena in astrophysics —- spanning a remarkable range in size, velocity, and energy output. Of particular interest are the systems capable of generating relativistic ejecta — accelerating material to nearly the speed of light — as these systems generate physical conditions that cannot be reproduced in laboratories on Earth. In this talk I

The baryon content of the universe is tightly constrained by big-bang nucleosynthesis and the cosmic microwave background. However, in the local universe only about 10% of the baryons are found in galaxies. It is natural to look for the remaining baryons in the intergalactic medium (IGM), but only ~50% are found there. According to cosmological

Recent observations of gravitational waves from merging double-compact-object binaries have reignited an explosive interest in the formation and evolution of compact objects in binary-star systems. However, by the time a compact-object binary merges and produces the gravitational-wave signals we observe, much of the evolutionary history of the system is washed away. By combining binary population

The James Webb Space Telescope (JWST) is revolutionizing the field of exoplanet atmospheric science with its unprecedented stability and wavelength coverage. From revealing previously unexplored chemistry to signatures of 3-dimensional processes, exoplanet atmospheric observations — in particular from transiting exoplanets — are providing key insights to understand the interiors of these distant worlds. In this

More than 40 years ago, X-ray astrophysicists sought a way to improve the energy resolution of non-dispersive X-ray spectrometers for the Advanced X- Ray Astrophysics Facility (now Chandra). What emerged was something entirely new – the thermal detection of individual X-ray photons and the ability to measure their energies with extreme precision. Over the subsequent