Wine and Cheese Spring 2017

This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Spring 2017.

Wine and Cheese sessions with one talk 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.

January 30th

Michael Fall (STScI)

Formation and Evolution of Star Clusters: A Simple, Unified Picture
This CAS seminar presents a simple, unified picture for the formation and evolution of star clusters. These objects are important in the structure and evolution of galaxies, primarily as the sites of star formation and stellar feedback. The seminar is organized around the mass function of star clusters (i.e., the spectrum of cluster masses) and how it evolves with time (age). Observations show some remarkable similarities in the mass functions of young star clusters in different galaxies, analogous to the similarities in stellar initial mass functions (IMFs). Explaining the near universality of the mass functions of star clusters is one of the goals and successes of the theory presented here. A byproduct of this theory is a unified concept of star clusters of all types (associations, open clusters, globular clusters, etc). In the new picture, clusters are characterized primarily by their masses and ages. The seminar is aimed at a broad audience of theorists and observers.

February 6th

Stephen Rinehart (GSFC)

The Transiting Exoplanet Survey Satellite (TESS): Opening the Door for Comparative Planetology
The idea that planets exist beyond our own solar system has been a feature of science fiction for many years, but it is only in the past few decades that the science fact of exoplanets has become known. With advances in ground based radial velocity measurements and the success of the Kepler mission, there are now over 1,000 confirmed exoplanets, and we continue to be amazed by the diversity and complexity of planetary systems. The Transiting Exoplanet Survey Satellite (TESS) will be the next step in this voyage of discovery. Kepler’s focus was on conducting a census of planets and on understanding the population statistics; TESS will find nearby planets amenable to detailed follow-up observations, so that we may begin to be able to truly understand these new worlds.

Andrew Ptak (GSFC)

The Survey and Time-domain Astrophysics Research eXplorer (STAR-X): Surveying the Ever-Changing Universe
STAR-X is a mission proposal that was submitted last December in response to the NASA MIDEX call. If selected it will launch in 2023 which is well positioned to complement LSST, WFIRST, JWST, Euclid, and SKA. The main science goals will be:
- Discover what powers the most violent explosions in the Universe
- Understand how black holes grow across cosmic time and mass scales
- Measure how structure formation heats the majority of baryons in the Universe
This talk will discuss these science goals and how they drove the design of STAR-X, which consists of an X-ray telescope with a 5” nearly-uniform PSF across a 1 deg. FoV and a rapid response capability.

February 13th

David Nataf (JHU)

The Extinction Curve toward the Bulge and Implications for the WFIRST Microlensing Campaign
The interstellar extinction toward the inner Milky Way is known to be significant (reaching Av ~ 80), variable, and non-standard in wavelength dependence. The issue of the net extinction, and first-order wavelength dependence, is largely solved by means of photometric data from OGLE (optical gravitational lensing experiment) and VVV (Vista Variables in the Via lactaea survey). Some uncertainties remain in mapping differential extinction, and extrapolating the extinction to other wavelengths. I place special emphasis on how it will affect the WFIRST microlensing campaign, a ~5-year, ~360 day programme that will be part of WFIRST's core programme.

Yi-kuan Chiang (JHU)

Galaxy Proto-clusters as an Interface between Structure, Cluster, and Galaxy Formation
Proto-clusters, the ancestor large-scale structures of present-day galaxy clusters, are unique laboratories to study dark matter assembly, cosmic baryon cycle, galaxy growth, and environmental impact on galaxy evolution. We extract LCDM predictions for the basic physical properties and observational signatures of galaxy proto-clusters as a function of cosmic time and cluster mass. Next I will talk about observation strategies and our ongoing efforts to search for and characterize z>~2 proto-clusters in photometric and spectroscopic galaxy surveys. I will then discuss cluster progenitors in the context of cluster formation, galaxy evolution and cosmic star formation, highlighting their unique roles linking scales from large to small, and epochs form active star-formation to quenching.

February 20th

Lucas Parker (JHU)

The Cosmology Large Angular Scale Surveyor
The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to observe the polarization of the Cosmic Microwave Background (CMB) with the primary science goal of detecting the gravitational waves generated in the earliest moments of our universe. CLASS is unique among CMB polarimetry experiments in its frequency and angular scale coverage, designed to maximize sensitivity to the primordial gravitational wave signal at the largest angular scales and with frequency span to reject both dust and synchrotron foreground emission. The CLASS survey began observations in 2016 with a 38 GHz telescope, and will be deploying two 93 GHz band telescopes and a dichroic 150/220 GHz telescope over the next two years. This talk will describe the CLASS experiment design and give an update on the state of the survey.

Graeme Addison

Cosmic Inconsistency?
The precision of a range of cosmological measurements has improved rapidly in recent years. While no individual data set provides compelling evidence for physics beyond the standard LambdaCDM model, the values of parameters, particularly the Hubble constant, inferred from different data sets now exhibit significant tension. I will discuss how measurements from the early universe and more local, low-redshift observations interact to provide cosmological constraints and why it is challenging to accommodate current data in either the standard model or some commonly-considered extensions.

March 6th

Kate Rowland

Caught in the act: charting galaxy transformation over cosmic time
One of the key problems in astrophysics is understanding how and why galaxies switch off their star formation, building the “red-sequence” that we observe in the local Universe. Post-starburst (“E+A”) galaxies, where a galaxy has recently undergone a massive starburst, are sufficiently common at z~1-2 that they may contribute significantly to the growth of the red-sequence at this important epoch. It is not well known how much post-starburst galaxies contribute to the build-up of the red sequence at z<1, due to small number statistics in previous redshift surveys, and aperture bias at very low redshifts (e.g. in SDSS). Using wide-area photometric and spectroscopic surveys I will explore the gas, dust and stellar population properties of post-starburst galaxies to determine whether these galaxies are quenching, and determine how important they could be for accounting for the growth of the red galaxy population.

Jeremy Schnittman (GSFC)

Radiation Transport in Dynamic Spacetimes
We present early results from a new radiation transport calculation of gas accretion onto merging binary black holes. We use the Monte Carlo radiation transport code Pandurata, now generalized for application to dynamic spacetimes. The time variability of the metric requires careful numerical techniques for solving the geodesic equation, particularly with tabulated spacetime data from numerical relativity codes. Using a new series of general relativistic magneto-hydrodynamical simulations of magnetized flow onto binary black holes, we investigate the possibility for detecting and identifying unique electromagnetic counterparts to gravitational wave events.

March 27th

TBD

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April 3rd

Massimo Ricotti (UMd)

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April 10th

Jay Felix Lockman (NRAO)

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April 17th

TBD

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May Day

Philip Hopkins (Caltech)

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