Wine and Cheese Spring 2021: Difference between revisions
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'''Astrophysical Charge eXchange: From the Laboratory to the Cosmos'''<br> | '''Astrophysical Charge eXchange: From the Laboratory to the Cosmos'''<br> | ||
Comets, planets, star-forming galaxies, supernova remnants, and galaxy clusters can all produce rich X-ray emission spectra. Disentangling the individual emission lines and processes that form them teaches us about the formation of these objects. The X-ray spectrum resulting from charge exchange (CX) - which involves a collision between an ion and a neutral atom or molecule - varies strongly based on the present ions, atoms or molecules, and the velocity of the collision. With a reliable CX model, this process can be used as a diagnostic tool for understanding neutral and ion density distributions, ion temperatures, elemental abundances, and ion charge state distributions in these environments. A reliable CX model requires a set of accurate, velocity-dependent cross-sections for a wide range of collision velocities and any relevant ions and neutrals that might be observed astrophysically. Theoretical methods used for calculating these cross-sections are often only relevant for a subset of these parameters, and these calculations must be benchmarked against experiments when possible. I introduce the process for preparing and testing the reliability of a CX model and provide examples of spectra in which this process is of particular importance. | Comets, planets, star-forming galaxies, supernova remnants, and galaxy clusters can all produce rich X-ray emission spectra. Disentangling the individual emission lines and processes that form them teaches us about the formation of these objects. The X-ray spectrum resulting from charge exchange (CX) - which involves a collision between an ion and a neutral atom or molecule - varies strongly based on the present ions, atoms or molecules, and the velocity of the collision. With a reliable CX model, this process can be used as a diagnostic tool for understanding neutral and ion density distributions, ion temperatures, elemental abundances, and ion charge state distributions in these environments. A reliable CX model requires a set of accurate, velocity-dependent cross-sections for a wide range of collision velocities and any relevant ions and neutrals that might be observed astrophysically. Theoretical methods used for calculating these cross-sections are often only relevant for a subset of these parameters, and these calculations must be benchmarked against experiments when possible. I introduce the process for preparing and testing the reliability of a CX model and provide examples of spectra in which this process is of particular importance. | ||
=22 February= | |||
==Sarah Milholland (Princeton)== | |||
'''Tidal Sculpting of Short-Period Exoplanets'''<br> | |||
Multiple-planet systems composed of close-in super-Earth/sub-Neptune-sized planets are ubiquitous, representing the dominant outcome of planet formation. This population exhibits predictable hallmarks of architectural regularity and uniformity, such as low eccentricities and inclinations, similar orbital spacings, and intra-system correlations in planetary masses and radii. On top of this first-order structure, however, these systems also exhibit surprising anomalies that require explanation. Examples include (1) ultra-short period planets, whose extremely-irradiated orbits have been separated off from the rest of their systems; (2) planets piled up wide of mean-motion resonances; and (3) a subset of Neptune-sized planets that show signs of radius inflation. In this talk, I will propose that tidal dynamics can account for these specific anomalies and more. Specifically, I will discuss the critical role of enhanced tidal dissipation due to non-zero planetary axial tilts (obliquities), which arise by way of prevalent dynamical resonances. I will highlight strategies for testing these tidal theories and observing obliquities directly in the future. | |||
Revision as of 15:01, 8 February 2021
This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Spring 2021.
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. Sessions in the Graduate Student Series will have three 15 minute talks, each with 5 minutes for questions.
Back to W&C Schedule
01 February
Vadim Burwitz (MPE)
The eROSITA X-ray Telescope Onboard the Spektr-RG Observatory: First Results
In my talk I will describe the eROSITA X-ray telescope onboard the Russian-German mission Spektr-RG that was launched in July 2019 from Baikonur. After an inflight calibration and performance verification phase the all sky survey commenced in December 2019. Since then two all sky surveys have been completed. Work is ongoing to analyse the rich yield of data. I will also present an overview of the first exiting scientific results that have been obtained over the last year (from stars, x-ray binaries to AGN, Clusters as well as diffuse X-ray emission).
08 February
Xinfeng Xu (JHU)
Extreme Outflows in Quasars: Most Energetic & Largest Accelerated Outflows
Supermassive black holes (SMBHs) are believed to exist in the center of almost all massive galaxies, and the active ones are named “active galactic nuclei” (AGN). Quasars are among the most luminous AGNs and show ubiquitous outflows, where blue-shifted absorption and emission lines are attributed to sub-relativistic (~1000 - 10,000 km/s) mass ejection. Outflows could be the prime candidates for producing various AGN feedback processes in galactic-scale: curtailing the growth of the host galaxy, explaining the relationship between the masses of the central black hole and the galaxy’s bulge, and chemical enrichment of the surrounding environment (ICM and IGM). In this talk, I will present my research progress on discovering quasar outflows with extreme physical properties (energies and accelerations), where our data was collected by the Hubble Space Telescope.
Renata Cumbee (UMCP/GSFC)
Astrophysical Charge eXchange: From the Laboratory to the Cosmos
Comets, planets, star-forming galaxies, supernova remnants, and galaxy clusters can all produce rich X-ray emission spectra. Disentangling the individual emission lines and processes that form them teaches us about the formation of these objects. The X-ray spectrum resulting from charge exchange (CX) - which involves a collision between an ion and a neutral atom or molecule - varies strongly based on the present ions, atoms or molecules, and the velocity of the collision. With a reliable CX model, this process can be used as a diagnostic tool for understanding neutral and ion density distributions, ion temperatures, elemental abundances, and ion charge state distributions in these environments. A reliable CX model requires a set of accurate, velocity-dependent cross-sections for a wide range of collision velocities and any relevant ions and neutrals that might be observed astrophysically. Theoretical methods used for calculating these cross-sections are often only relevant for a subset of these parameters, and these calculations must be benchmarked against experiments when possible. I introduce the process for preparing and testing the reliability of a CX model and provide examples of spectra in which this process is of particular importance.
22 February
Sarah Milholland (Princeton)
Tidal Sculpting of Short-Period Exoplanets
Multiple-planet systems composed of close-in super-Earth/sub-Neptune-sized planets are ubiquitous, representing the dominant outcome of planet formation. This population exhibits predictable hallmarks of architectural regularity and uniformity, such as low eccentricities and inclinations, similar orbital spacings, and intra-system correlations in planetary masses and radii. On top of this first-order structure, however, these systems also exhibit surprising anomalies that require explanation. Examples include (1) ultra-short period planets, whose extremely-irradiated orbits have been separated off from the rest of their systems; (2) planets piled up wide of mean-motion resonances; and (3) a subset of Neptune-sized planets that show signs of radius inflation. In this talk, I will propose that tidal dynamics can account for these specific anomalies and more. Specifically, I will discuss the critical role of enhanced tidal dissipation due to non-zero planetary axial tilts (obliquities), which arise by way of prevalent dynamical resonances. I will highlight strategies for testing these tidal theories and observing obliquities directly in the future.
