Cosmological Coupling in the Era of the Dark Energy Spectroscopic Instrument

Kevin Croker

Assistant Research Scientist

Arizona State University

Website

Recent advances in General Relativity point toward unanticipated, and dynamic, relations between ultracompact objects and the universe they inhabit. The possibility for strongly gravitating systems, like astrophysical black holes (BHs) and their embedding cosmology, to directly interact has been dubbed "cosmological coupling." We focus on recent results from the DOE Stage IV Dark Energy (DE) Spectroscopic Instrument (DESI), which strongly suggest that DE is dynamical. Using typical empirical models for the cosmic star-formation rate density as a proxy to BH production, we show that the DESI-inferred time-evolution of DE is consistent with cosmologically coupled stellar-collapse BHs as the source of DE. The predicted cosmological expansion rate today, H₀ = 69.94 ± 0.81 km/Mpc/s, is in excellent agreement with H₀ = 69.58 ± 1.58 km/Mpc/s recently reported by the Chicago-Carnegie Hubble Program using Cepheid, Tip of the Red Giant Branch, and J-Region Asymptotic Giant Branch stellar distance-ladder calibrations. With DESI Redshift Space Distortions and Year 3 datasets on the horizon, we highlight exciting prospects for further observational confrontation in the near term.

Globular Clusters: Astronomical factories of gravitational-wave and electromagnetic transients

Kyle Kremer

Assistant Professor

UC San Diego

Website

It is now widely established that globular clusters host robust populations of white dwarfs, neutron stars, and black holes throughout their lifetimes. Within clusters, dynamical processes enabled by stellar densities thousands to millions of times larger than typical galactic environments facilitate interactions involving these stellar remnants that power an array of astrophysical transients. In particular, stellar clusters have emerged as an important formation site for merging black hole binaries, similar to those recently detected as gravitational wave sources by the LIGO/Virgo/KAGRA collaboration. In this talk, I will review our current understanding of stellar remnants in globular clusters, discussing current observational evidence and the ways stellar remnants influence the dynamical evolution of their hosts. I will describe the formation of merging binaries detectable as gravitational wave sources and connect to a number of other sources observed in clusters including black hole+star binaries, tidal disruption events, radio pulsars, and fast radio bursts. In the coming years/decades, globular clusters promise to be a nexus for transient astrophysics, connecting to current/next-generation gravitational wave facilities, all-sky surveys like the Rubin Observatory, and state-of-the-art radio telescopes.

25 Years of Science with Chandra

Hans Moritz Günther

Research Scientist

MIT Kavli Institute for Astrophysics and Space Research

Website

Chandra is one of NASA’s "Great Observatories" and was launched in 1999. In this talk, I will review Chandra’s history and instruments and show highlights from an absolutely astonishing 25 years of science observations.

A "30 ft orbiting X-ray telescope" was first proposed by Riccardo Giacconi in the 1960s, and today’s Chandra grew out of that idea. I will describe the mirrors, instruments, and technologies in Chandra and show how it was put together and launched into orbit. Chandra has observed a vast range of objects in the last 25 years, and I will highlight and explain just a few of them: quasars, jets, SMBH, galaxy clusters, SNR, stars, star forming regions, planets, and comets.

I will show some examples of how we deal with the challenges of operating a aging observatory. Unfortunately, Chandra’s funding environment is uncertain; I will provide an update on NASA’s current funding promises and plans.

Schematic of the Chandra spacecraft
Credit: NGST & NASA/CXC

Basins of Attraction in the Local Universe

Brent Tully

Astronomer Emeritus

University of Hawaiʻi Institute for Astronomy

Structure in the Universe is believed to have evolved out of quantum fluctuations seeded by inflation in the early Universe. These fluctuations lead to density perturbations that grow via gravitational instability into large cosmological structures. In the linear regime, the growth of structure is directly coupled to the velocity field since perturbations are amplified by attracting (and accelerating) matter. Surveys of galaxy redshifts and distances allow one to infer the underlying density and velocity fields. Here, assuming the LCDM standard model of cosmology and applying a Hamiltonian Monte-Carlo algorithm to the grouped Cosmicflows-4 (CF4) compilation of 38,000 groups of galaxies, the large scale structure of the Universe is reconstructed out to a redshift corresponding to ~30,000 km/s. We consequentially produced the largest density and velocity field maps of the Universe to date. Our method provides a probabilistic assessment of the domains of gravitational potential minima: basins of attraction (BoA). Earlier Cosmicflows catalogs suggested the Milky Way Galaxy was associated with a BoA called Laniakea. Now with the newer CF4 data, there is a slight probabilistic preference for Laniakea to be part of the much larger Shapley BoA. The largest BoA recovered from the CF4 data is associated with the Sloan Great Wall with a volume within the sample of 15.5×10⁶ (Mpc∕h)³, which is more than twice the size of the second largest Shapley BoA.

A glimpse into the Milky Way’s distant past: Unravelling the Galaxy’s early assembly history with large stellar surveys

Danny Horta

Flatiron Research Fellow

Center for Computational Astrophysics, Flatiron Institute

Website

Unravelling galaxy formation theory requires understanding galaxies both at high and low redshifts. A possible way to connect both realms is by studying the oldest stars in the Milky Way (i.e., the proto-Galaxy). Our ability to resolve individually millions of stars in the Galaxy provides us with the opportunity to decipher the intricate processes of galaxy formation in a detail that is unmatched by any other galaxy in the Cosmos. Therefore, the time is ripe to study the oldest parts of the Milky Way, and from them unravel its early mass assembly history. Such results, in addition to placing strong constraints on how our Galaxy formed, are also complementary to the new exciting results of the high-redshift Universe delivered by the JWST telescope. In this talk, I will present new findings aiming to piece together the earliest stages of formation of the Milky Way by examining the chemistry, kinematics, and orbits of the oldest stars in the Galaxy. I will also show fresh results concerning the structure and mass of the Milky Way’s proto-galactic fragments. I will then place these observational findings in the wider context of the many possible assembly histories by comparing with expectations from cosmological simulations. The findings I will present help answer (but raise more) fundamental questions on the genesis of our Galaxy.

Data inspired simulations of flares resulting from collisional shearing with the MURaM radiative MHD code

Matthias Rempel

Senior Scientist

High Altitude Observatory

Website

The NOAA active region AR 11158 is a well-studied flare productive AR that led to the occurrence of more than 30 flares, including one X and multiple M flares. A characteristic feature of AR 11158 was the formation of a collisional polarity inversion line in response to the emergence of 2 bipolar active regions in proximity and their interaction during the emergence process. It has been proposed that the collisional shearing in combination with the associated flux cancellation is the primary process that energizes the corona and leads to strong flares in these types of active regions. We use the MURaM radiative MHD code that has the capability to simulate the coupled solar atmosphere from the upper convection zone into the lower solar corona to test the collisional shearing scenario. We conduct two studies: (1) A simplified bipolar setup with colliding sunspots that allows us to study the effect of speed, distance and sunspot coherence during collision on the energy built up and resulting flares; (2) A quadrupolar setup that mimics AR 11158. To this end we extract the centroid positions of the 4 involved polarities and start from a quadrupolar simulation setup of spots with flux content and initial positions like AR 11158. By imposing sub-photospheric foot point motions we move the 4 sunspots along the observed centroid paths and create a collisional polarity inversion line through collision of the central non-conjugate polarities. In both studies we find that flares resulting from collisional shearing are very effective, about 50% of the stored free energy is released in a single flare. The coherence of the spots during the collision process determines the amount of flux cancellation and through that the timing of transition from a sheared magnetic arcade to a magnetic flux rope. In the study (2) the process builds up free energy in the corona exceeding 4e32 ergs, which are released in a series of flares in the C to X range, with the X flare releasing about 2e32 ergs. The 4 strongest flares are associated with coronal mass ejections. We compute synthetic observables including photospheric, chromospheric, and coronal EUV and X-ray emission and study specifically observables that diagnose the pre-eruptive flux rope structure and highlight the location of reconnection sites leading to the destabilization of the flux system, which will be available from the Multi-slit Solar Explorer (MUSE) as well as the Chromospheric Magnetism Explorer (CMEx).

A new adaptive secondary mirror for astronomy

Mark Chun

Astronomer

University of Hawaiʻi Institute for Astronomy

I’ll present the motivations, goals, and early results of a new approach to building adaptive secondary mirrors (ASM). This work, in collaboration with The Netherlands Organization for Applied Research (TNO), has the potential to bring resolution and sensitivity gains over a wide wavelength range to a broad range of telescopes (large and small) using their existing suite of science instruments. For telescopes on Maunakea this is an effective doubling of the collecting area of the telescope. I’ll discuss recent results from the first of this “TNO-style” ASM on the NASA IRTF telescope and the status of the ASM for the University of Hawaii 2.2-meter telescope. Long-term development plans are in the works to scale the approach to larger ASMs (e.g. Keck) as well as to make these more readily and easily deployable to small 2-4-meter telescopes around the world.

Unveiling the Mysteries of the Early Universe with a Synergy of ALMA and JWST

Andreas Faisst

Assistant Research Faculty

Caltech

Website

For obtaining a complete picture of galaxies, multi-wavelength observations are crucial to observe their stars, gas, dust, and chemical composition. With Hubble, JWST, and ALMA operating at the same time, we find ourselves in an era where we can jointly observe the UV, optical, and infrared light. In my talk, I will present recent results obtained by the synergy of these observatories on the properties of starburst and main-sequence galaxies, AGN, and the most dusty galaxies during the cosmic dawn. As part of this, I will introduce the contribution of three new programs with JWST (ALPINE NIRSpec/IFU program and MIRI/MRS PAH survey) and ALMA (CHAMPS 1.2mm survey) with which we will study the chemical compositions of z=4-6 galaxies, search for the most dust-obscured sources during the Epoch of Reionization, and measure for the first time spatially resolved PAH dust emission in z=1 galaxies. I conclude by highlighting the important future contributions to these topics by the next generation of infrared space telescopes, including SPHEREx and PRIMA.

AGB Asteroseismology: Evolved Variable Stars as Laboratories for Stellar Evolution in Real Time

Meridith Joyce

Assistant Professor

University of Wyoming

Website

Most of stellar evolution proceeds far too slowly to be observed on human timescales, but thermally pulsing asymptotic giant branch (TP-AGB) stars can provide an unusual exception. Thermal pulses are violent, rapid helium shell flashes experienced by sun-like stars at the end of their lives, during which the star’s brightness can change by more than an order of magnitude in only ~100 years. However, given the short duration of the pulses compared to the several-thousand-year gaps between them, it is rare to catch a star in this phase of its life.

The TP-AGB stars T Ursae Minoris and R Hydrae are confirmed to be in the midst of thermal pulses using asteroseismology, a deduction enabled by observing two dynamical behaviors simultaneously: thermal pulses, on the timescale of hundreds of years, and acoustic p-mode pulsations, on the timescale of hundreds of days. Our results hinge crucially on (1) multi-source, longitudinal observational data spanning centuries and (2) large grids of evolutionary and asteroseismic calculations. In this talk, I will discuss the application of the “seismic stellar evolution” modeling approach to study late-stage, classically variable stars, thus showcasing the state-of-the-art in asteroseismology of large-amplitude pulsators like AGB stars.

Zooming in on the Age of Exocomets: New Insights into Terrestrial Planet Formation with JWST

Cicero Lu

Science Fellow

Gemini Observatory

Website

The past decade has witnessed two major advances in planet formation science: (1) the explosive discovery of over 5,000 new exoplanets around mature stars, and (2) the characterization of planet-forming materials in disks around very young (<3 Myr) stars, known as protoplanetary disks. However, a critical intermediate stage must be added to the current paradigm, as exoplanet demographics and protoplanetary disk studies appear to paint contradictory pictures. For instance, while thousands of sub-Neptunes and super-Earths have been discovered, it remains unclear how terrestrial planets acquire or sustain the volatiles for their atmospheres during the epoch of violent, impact-driven events, and how small bodies influence this process. Exocomets likely play an important role, delivering gas and dust as they migrate from exo-Kuiper belts through the terrestrial zone into the innermost regions of debris disks. With its unmatched infrared capabilities, JWST has pushed the boundaries of planet formation by enabling the first detection of warm molecular gas in these 10-100 Myr disks undergoing pebble drift and exocometary activity. In this talk, I will present recent findings on young planetary systems hosting exocomets using JWST NIRSpec and MIRI data, focusing on the first detection of CO fundamental emission in a debris disk and a giant collision observed with MIRI IFU. I will also discuss the implications of warm gas detections on the young exoplanets' atmospheres and the path forward using the synergy between JWST and ground-based observatories like Gemini.

Twilight Discovery of near-Sun Asteroids and Naked-eye Comets at Palomar Observatory

Bryce Bolin

Research Scientist

Eureka Scientific

Website

While the majority of solar system objects discovered by wide field surveys are ordinary, they also provide the opportunity to discover hidden gems such as interstellar objects, near-Sun asteroids, and bright comets. These provide opportunities to characterize extrasolar planetesimals, search for new sources of asteroids in the inner solar system, and study the composition of the protoplanetary disk. I will describe survey techniques used to discover these hidden gems in observations of the near-Sun sky during twilight in current and next-generation surveys, such as the Zwicky Transient Facility and the Rubin Observatory. I will describe three examples of twilight solar system results: 1.) the discovery and follow-up observations of (594913) ‘Ayló’chaxnim, the first known asteroid possessing an aphelion entirely within the orbit of Venus, 2.) the recovery of interstellar comet 2I/Borisov, and 3.) the discovery of naked-eye comet C/2022 E3 (ZTF). I will discuss the behind-the-scenes work of using machine learning in these results and their implications for the formation of the solar system and the composition of extrasolar and solar system planetesimals.

Into the First Billion Years with JWST

Rohan Naidu

NASA Hubble Fellow

MIT Kavli Institute for Astrophysics and Space Research

Website

One of the last great unknowns in our history of the universe is when and how the first galaxies emerged after the Big Bang. These galaxies transformed the cosmos—they illuminated the invisible scaffolding of dark matter that underpins the universe, they ionized the intergalactic reservoirs of hydrogen, and they synthesized the elements that would one day seed life on Earth. Thanks to JWST, these enigmatic galaxies are finally coming into view. In this talk I will present latest results on these sources, and preview ongoing experiments I am leading. I will discuss new classes of galaxies being revealed at the highest redshifts such as remarkably luminous early systems, a surprisingly abundant population of obscured black holes (“Little Red Dots”), and extremely metal-poor (perhaps metal-free?) sources. I will describe novel strategies to hone in on the elusive protagonists of cosmic reionization, the last large-scale process that touched almost every baryon in the universe. Throughout, I will outline how in the coming years JWST, Roman, and the upcoming ELTs promise a once-in-a-generation expansion of the astrophysical frontier to the brink of the Big Bang.

IRTF operations and the future, and an idea for exploring accretion disks in Cataclysmic Variables

Warren Skidmore

Observatory Instrumentation System Scientist

Thirty Meter Telescope International Observatory

In this talk I’ll give a brief personal history to provide the context for the research work that I’d like to follow and how I see where I’d be able to contribute to ensuring that the IRTF has an exciting and productive future.

I’m eager to pursue my research interests in Cataclysmic Variables (CVs) and related time domain topics. I’ll describe how, in the near term, I would like to employ the technique of Kepler Tomography to investigate the properties of CV accretion disks and uncover clues about the source of the viscosity in those disks.

The skills and experiences that I have in project planning and development will allow me to help in many areas of IRTF operations, community engagement, resource management and strategic planning. I’ll mention some specific areas where I believe I can support and reinforce existing processes and efforts at IRTF, and a few ideas for new initiatives that I should be able to advance.

Atmospheres on Rocky Exoplanets: Promising Early Results from JWST

Ryan J. MacDonald

NASA Sagan Fellow

University of Michigan

Website

To understand the habitability of terrestrial exoplanets, we must first determine which rocky worlds have atmospheres. Terrestrial planets orbiting small M-dwarf stars are currently the focus of observational searches for air on rocky exoplanets, due to the small size of their host star increasing our sensitivity to planetary atmospheres. However, the extreme-UV radiation and frequent flaring of M-dwarfs pose problems for the long-term atmospheric survival of such rocky worlds.

JWST spectroscopic observations are finally now offering the sensitivity to detect and characterize atmospheres on rocky exoplanets. A core goal of the JWST mission is therefore to find the first observational evidence of terrestrial exoplanet atmospheres and to reveal the compositional diversity of rocky planets in our galaxy.

In this colloquium, I will report the progress to date on identifying rocky exoplanet atmospheres with JWST. After describing the main techniques used to search for rocky exoplanet atmospheres, I will present the most promising evidence to date of rocky exoplanet atmospheres. In particular, our results include tentative evidence for an atmosphere on a habitable zone rocky planet. Finally, I will discuss near-term prospects to confirm these initial signs of rocky exoplanet atmospheres.

Dr. Ryan MacDonald is a NASA Sagan Fellow at the University of Michigan. His research focuses on the atmospheric characterization of exoplanetary atmospheres using space- and ground-based telescopes.

New eyes on the cosmic web—Ultranarrowband imaging with the Dragonfly telescopes

Deborah Lokhorst

Herzberg Instrument Science Fellow

NRC Herzberg Astronomy and Astrophysics Research Centre

Website

The vast majority of baryons in the universe exist outside galaxies, in the circumgalactic and intergalactic medium (CGM and IGM). These regions play a crucial role in fueling star formation in galaxies, yet their properties remain poorly understood. The mechanisms by which gas in the CGM gets into galaxies—and is expelled through galactic feedback in turn—are still under debate. Moreover, the total mass of the CGM surrounding galaxies remains uncertain due to the near-invisible nature of the CGM and IGM.

To address this open question, we have developed a telescope to detect the extremely faint emission from the CGM. We combined novel ultra-narrow bandpass imaging technology with the Dragonfly Telephoto Array (a mosaic-design telescope composed of Canon telephoto lenses) to enable sensitivity to low surface brightness line emission. A 3-lens pathfinder version of the ultranarrowband upgrade to Dragonfly confirmed this capability and was followed by a 120-lens version (the Dragonfly Spectral Line Mapper), which we used to carry out an imaging campaign of H-alpha, [NII], and [OIII] emission in the CGM of local galaxies. We are currently upgrading to a 1064-lens version of this array, which will have the power to fully map the CGM of local galaxies and the potential to detect the filaments of the IGM.

Extragalactic Globular Clusters and Exotic Compact Binaries

Arunav Kundu

Principal Investigator

Eureka Scientific

Globular clusters are the closest analogs to simple stellar systems and are found in large numbers in the halos of galaxies. They encode interesting information about the formation and evolutionary histories of their host galaxies. These extremely dense stellar systems are also prime locations for enhanced stellar dynamical interactions, which leads to the efficient formation of rare systems such as accreting neutron star and black hole X-ray binaries. A significant fraction of the mergers discovered by gravitational wave detectors such as LIGO may reside in globular clusters. I will talk about observations of globular clusters and some of the exotic binary systems associated with them.

I will also discuss possible ways in which the already highly productive science return of the IRTF can be enhanced to further explore such science, and its prime mandate of supporting Solar System and Planetary Defense studies. Changes in some aspects of proposal processes, data archiving and calibration, interaction with the local community, and hiring practices may help the facility run smoother, with higher science impact, and even better rapport with the local community.

From 7 minutes to 70000 years: The golden era of binary star astrophysics

Kevin Burdge

Pappalardo Fellow in Physics

MIT Department of Physics

Website

Modern synoptic time domain surveys are revolutionizing our understanding of compact objects in binary systems, and transforming the field of gravitational wave multi-messenger astrophysics. In this talk, I will highlight some recent advances in our understanding of white dwarfs, neutron stars, and black holes in binary (and triple) systems. These results encompass phenomena which span orbital periods of 7 minutes to >70000 years, and have major implications in our understanding of compact object physics, as well as binary stellar evolution. I will conclude with a discussion of upcoming facilities including the Vera Rubin Observatory and LISA, and technological advances such as CMOS based imagers that will propel this field into its golden era.

TBA

Carey Lisse

Principal Research Scientist

Johns Hopkins University Applied Physics Lab

Coming soon.