Wine and Cheese Spring 2026: Difference between revisions
No edit summary |
|||
| Line 53: | Line 53: | ||
=02 March= | =02 March= | ||
== | ==Rajes Ghosh (JHU)== | ||
''' | '''Gravitational Waves as Probe of New Physics'''<br> | ||
A decade after LIGO’s historic detection of GW150914, gravitational wave astronomy has matured into a powerful tool for uncovering new physics beyond the standard paradigm. In this spirit, I will present a novel approach to testing the Kerr paradigm using the ringdown phase of binary mergers, where the final black hole relaxes by emitting quasi-normal modes. While most existing works assume that deviations from Kerr preserve its defining symmetries, e.g., stationarity, axisymmetry, and circularity, these assumptions can indeed be broken in the presence of environmental effects or dynamical modifications of gravity. I will focus in particular on potential violations of Kerr circularity and demonstrate how quasi-normal mode spectroscopy can be used to probe such departures. Using GW150914 as a case study, we place stringent observational constraints on such deviations. This symmetry-based test also offers a novel avenue for assessing the robustness of various foundational results, like black hole uniqueness and no-hair theorems, in the context of astrophysical black holes. | |||
=09 March= | =09 March= | ||
== | ==Michael Eracleous (PSU)== | ||
''' | '''The Central Engines of LINERs'''<br> | ||
Low-Ionization Nuclear Emission-line Regions (LINERs) have been a puzzle and the subject of debate since their identification in 1980. They are defined through the strengths of their low-ionization oxygen emission lines and are very common (found in about half o nearby galaxies). Their optical emission-line spectra can be attributed to shocks, or photoionization by a hard continuum from an active nucleus, or photoionization by unusually hot stars. I will discuss, in historical perspective, the work I have been doing with my collaborators and students trying to identify the power source in LINERs and present the emerging picture: LINERs are seemingly feeble active nuclei that can photoionize the circumnuclear gas in their immediate vicinity (within a few tens of parsec) but also produce outflows that shock the interstellar gas at larger distances (within several hundred parsec). As such, they are mechanical feedback machines whose influence on their host galaxies remains to be fully appreciated. | |||
=23 March= | =23 March= | ||
Revision as of 14:45, 27 February 2026
This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Spring 2026.
Wine and Cheese sessions with one speaker will have a 50 minute talk with 10 minutes for questions. Sessions with two speakers will have two 25 minute talks, each with 5 minutes for questions.
Back to W&C Schedule
26 January
Colin Hamill (AAS)
Astronomy on the Hill: Federal Funding and Dark & Quiet Skies Policy
The landscape of federal science policy has shifted dramatically over the past year. As the FY2026 federal funding cycle concludes, this talk will provide a brief overview of the current fiscal situation for the astronomical sciences, as well as an outlook for FY2027 and beyond. We will then examine the Dark & Quiet Skies initiative, a global effort to preserve the night sky from light pollution and radio frequency interference from satellites. We will review recent regulatory developments in the space environment and highlight how the astronomical community works with commercial space operators and the federal government to ensure a sustainable orbital environment. The talk concludes with a discussion of how scientists at all career stages can engage with policymakers to ensure astronomy and science remains a priority on Capitol Hill.
09 February
Chris Nagele (JHU)
Radiation Transfer Simulations of Black Hole Spectra
Spectra from accreting black holes are one of our most powerful tools for understanding these enigmatic objects. These spectra, however, are not well understood. For example, stellar mass black holes and supermassive black holes exhibit different spectral properties, with the stellar mass black holes changing between different spectral states (hard and soft states) while the supermassive black holes have more uniform spectral slopes. We run radiation transfer post-processing of general relativistic magnetohydrodynamical simulations of black hole accretion, in order to generate spectral predictions. We use two radiation transfer codes, Pandurata and PTransX, to solve for thermal balance and ionization balance in different parts of the simulation. Our spectra are remarkably similar to observed trends, with a clear hard/soft dependence on accretion rate at M = 10 Msun and uniformly flat spectra in the supermassive regime. We also compute high resolution spectra in order to simulate emission lines coming from the accretion disk near the black hole. Our spectra contain Fe Kalpha lines with equivalent widths (50-200 eV) and line shapes consistent with observations. We find, however, that the breadth of these lines is due to several factors, and not simply to extreme relativistic motions near the black hole, as is almost always assumed. We discuss how physical quantities from our simulations can be incorporated into models which perform black hole parameter inference, thereby breaking some of the degeneracy associated with these models.
Stephen Schmidt (JHU)
Hot Jupiters are Inflated Primarily by Shallow Heating
The unexpectedly large radii of transiting hot Jupiters have led to many proposals for the physical mechanisms responsible for heating their interiors. While it has been shown that hot Jupiters reinflate as their host stars brighten due to heating deep in planetary interiors, young hot Jupiters also exhibit signs of delayed cooling possibly related to heating closer to their surfaces. To investigate this tension, we enhance our previously published hot Jupiter thermal evolution model by adding a parameter that allows for both deep heating and delayed cooling. We fit our thermal evolution models to a homogeneous, physically self-consistent catalog of accurate and precise hot Jupiter system properties in a hierarchical Bayesian framework. We find that hot Jupiters' interior cooling rates are reduced on average by 95%--98% compared to simpler anomalous heating models. The most plausible explanation for this inference is substantial shallow heating just below their radiative--convective boundaries that enables reinflation with much less deep heating. Shallow heating by Ohmic dissipation and/or temperature advection are therefore important components of accurate models of hot Jupiter atmospheres, especially in circulation models. If hot Jupiters are inflated primarily by shallow heating as we propose, then we predict that their observed phase curve offsets should increase with temperature in the range T_eq <~ 1500 K, peak in the range 1500 K <~ T_eq <~ 1800 K, and decrease in the range T_eq >~ 1800 K.
16 February
Jessica A. Gaskin (GSFC)
Preparing for the Next Astronomy and Astrophysics Decadal Survey (Astro2030)
The Astronomy and Astrophysics Decadal Survey, conducted once every ten years, establishes the community’s highest-priority ground- and space-based science goals and provides strategic guidance for future investments. NASA relies heavily on this guidance when shaping its long-term mission portfolio and budget. For the 2020 Decadal Survey, NASA supported a suite of community-led mission concept studies that articulated compelling science cases, assessed technical readiness, defined design reference missions, and developed high-level cost estimates, ensuring that the Decadal Committee was equipped with a robust and well-informed basis for its deliberations. As preparations begin for the next survey, Astro2030, NASA is again engaging the community to inform its planning. This includes soliciting broad feedback and convening two workshops—one in the spring and one in the fall of this year—to incorporate the evolving space environment, emerging technologies, and growing commercial capabilities before initiating any new NASA-sponsored mission concept formulation activities. This talk will provide an overview of the Decadal Survey process and outline NASA’s current plans and rough timeline for preparing for Astro2030.
23 February
Eileen Meyer (UMBC)
Crossing the Radio Divide: Radio Studies of Changing-Look AGN
While astronomers first discovered that super-massive black holes
(SMBH) can launch jets of relativistic plasma over 60 years ago, we
are still searching for the 'trigger' that turns a non-jetted SMBH
into a jetted one. Given typical lifetimes of millions of years (if
not longer), it might seem highly improbable to catch a black hole 'in
the act' of launching a brand-new relativistic jet. Yet that is
exactly what we believed happened in the case of 1ES 1957+654, a
nearby 'changing-look' active galaxy where long-term VLBA monitoring
caught a sudden radio brightening in spring of 2023 which we now
understand to be a new-born jet. Nearly 2 years on, we can now follow
the evolution of the plasma structures as seen in high-resolution
radio imaging, and speculate on the likely cause (and future) of this
unusual jet. I will place these findings in the larger context of
recent discoveries which blur the line between jetted/non-jetted (or
radio-quiet/radio-loud) black holes and show these types are more
changeable than we might have first believed. I will also make
connections between black hole outflows at all scales and in very
different conditions -- from TDEs to X-ray binaries, and speculate on
what may ultimately be the key to a successful jet launch.
02 March
Rajes Ghosh (JHU)
Gravitational Waves as Probe of New Physics
A decade after LIGO’s historic detection of GW150914, gravitational wave astronomy has matured into a powerful tool for uncovering new physics beyond the standard paradigm. In this spirit, I will present a novel approach to testing the Kerr paradigm using the ringdown phase of binary mergers, where the final black hole relaxes by emitting quasi-normal modes. While most existing works assume that deviations from Kerr preserve its defining symmetries, e.g., stationarity, axisymmetry, and circularity, these assumptions can indeed be broken in the presence of environmental effects or dynamical modifications of gravity. I will focus in particular on potential violations of Kerr circularity and demonstrate how quasi-normal mode spectroscopy can be used to probe such departures. Using GW150914 as a case study, we place stringent observational constraints on such deviations. This symmetry-based test also offers a novel avenue for assessing the robustness of various foundational results, like black hole uniqueness and no-hair theorems, in the context of astrophysical black holes.
09 March
Michael Eracleous (PSU)
The Central Engines of LINERs
Low-Ionization Nuclear Emission-line Regions (LINERs) have been a puzzle and the subject of debate since their identification in 1980. They are defined through the strengths of their low-ionization oxygen emission lines and are very common (found in about half o nearby galaxies). Their optical emission-line spectra can be attributed to shocks, or photoionization by a hard continuum from an active nucleus, or photoionization by unusually hot stars. I will discuss, in historical perspective, the work I have been doing with my collaborators and students trying to identify the power source in LINERs and present the emerging picture: LINERs are seemingly feeble active nuclei that can photoionize the circumnuclear gas in their immediate vicinity (within a few tens of parsec) but also produce outflows that shock the interstellar gas at larger distances (within several hundred parsec). As such, they are mechanical feedback machines whose influence on their host galaxies remains to be fully appreciated.
23 March
TBD
Title
Abstract
30 March
TBD
Title
Abstract
06 April
TBD
Title
Abstract
13 April
TBD
Title
Abstract
20 April
TBD
Title
Abstract
27 April
TBD
Title
Abstract
04 May
TBD
Title
Abstract