This is the unofficial website of the NSF AAPF program, run by the fellows themselves. For official information about the fellowship, please go to the NSF program announcement.
This year's AAPF symposium will be held from Friday 3 Jan 12:00 PM - Saturday 4 Jan 5:00 PM in Room 301A at the Hawai'i Convention Center prior to the 235th meeting of the American Astronomical Society.
We encourage all AAS attendees to come to our symposium! However we suggest you arrive at or after 2:15pm on Friday, since the first two and a half hours will be mainly NSF AAPF logistics and internal discussion.
Participants are required to abide by the AAS Anti-Harrassment Policy and the Guide to AAS Meeting Etiquette.
Accessibility: We are committed to making this symposium accessible to everybody. Please see the following link for more information: AAS 235 Accessibility.
Keynote - Surveying the Transient Universe
Ben Shappee, Institute for Astronomy, University of Hawai'i
For the first time, the entire visible sky is being surveyed for the violent, variable, and transient events that shape our universe. Surveys such as the All-Sky Automated Survey for Supernovae (ASAS-SN), the Asteroid Terrestrial-impact Last Alert System (ATLAS), The Zwicky Transient Facility (ZTF), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), and Gaia monitor the whole sky, at high cadence with a combined total of 11 (soon to be 14) telescopes distributed at 8 (soon to be 10) sites around and above the world. Each survey has a different cadence and depth. I will briefly review major ongoing transient surveys, contrasting their capabilities and goals. I will then use a handful of recent discoveries to highlight opportunities that these new capabilities present. I will focus on multi-messenger astronomy (with LIGO and IceCube); multi-wavelength astronomy (with Swift, NICER, MAXI, and Fermi); and high-cadence, high-precision observations (with Kelper and TESS). I will end reflecting on challenges for the field both now and in the LSST-era.
Panel - The Postdoc to Job Transition
Natalie Gosnell, Assistant Professor, Department of Physics, Colorado College
Jeffrey Silverman, Director, Data Science & Analytics at Samba TV
Ben Shapee, Assistant Professor, Institute for Astronomy, University of Hawai'i
Workshop - Engaging Non-STEMists in Your Science
Moiya McTier, Astrophysicist & Science Communicator
Moiya McTier has made a career of getting non-scientists excited about science, so she knows that it takes a different set of skills from talking to colleagues who are already interested in and somewhat knowledgable about your field. In this workshop, Moiya will teach you what she's learned, namely how to empathize with your non-scientist audience and build lessons that don't immediately scare them away. These techniques will work when you're giving outreach talks and preparing to teach a class for non-STEM majors.
This schedule is subject to change All times local Hawaiian. Click on the speaker name for their professional biography. Click on the talk title to scroll down to the abstract.
Discovering the First Exoplanets Around White Dwarf Stars with the Zwicky Transient Facility
Keaton Bell - University of Washington
Planetary materials orbiting white dwarf stars reveal the ultimate fate of the planets of the Solar System and exoplanet systems. Observed metal pollution and infrared excesses from debris disks support that planetary systems or their remnants are common around white dwarf stars. However, these are difficult to detect since a very high orbital inclination angle is required for a small white dwarf to be transited, and these transits have very short (minute) durations. The minuscule amount of time that these systems spend in transit can be overcome by a sufficiently wide and fast photometric survey. By obtaining more than 100 million images of white dwarf stars with 30-second exposures over three years, the Zwicky Transient Facility (ZTF) is likely to record the first exoplanetary transits of white dwarf stars. ZTF will also reveal new systems of transiting, disintegrating planetesimals like WD 1145+017. In this talk I demonstrate the promise of ZTF to unveil the population of exoplanets orbiting white dwarf stars.
Latest Results from the Askaryan Radio Array
Brian Clark - Michigan State University
The Askaryan Radio Array (ARA) is designed to be an ultra-high energy (UHE, >100 PeV) neutrino detector. ARA searches for neutrinos by burying clusters of antennas up to 200m deep in the ice near the South Pole, and looking for the radio waves emitted by the relativistic byproducts of neutrino-nucleon interactions in the ice. Five clusters, or stations, have been deployed so far. In this talk, I will discuss our recent search for a diffuse flux of neutrinos in four years of data from two stations. The search leveraged more than quadruple the livetime of our previous work, and resulted in the best limit set by an in-ice radio neutrino detector above ~100 PeV.
Cold Giant Worlds at the Frontier of Exoplanetary Science
Paul Dalba - University of California Riverside
Gas giant planets play lead roles in planetary systems. They dominate the budgets for angular momentum and planetary mass, their atmospheres hold clues about the environment in which the entire system formed, and their presence potentially has implications for the habitability of neighboring terrestrial worlds. Earth's proximity to the gaseous planets of the Solar System presents a great opportunity for comparative investigations with giant exoplanets. But there is a problem: nearly all of the giant exoplanets that have been characterized (i.e., had their mass, radius, and atmospheric composition measured) are strikingly different than the Jovian planets in the Solar System. These exoplanets live right next to their host stars, making them blisteringly hot and obscuring their connection to colder worlds like Jupiter or Saturn. I will present my efforts to narrow the disparity between well characterized giant exoplanets and the Solar System giant planets. Most methods used to discover exoplanets are biased against mature planets with large orbital distances. Yet, a useful sample of these exoplanets has been found and more are on the way. I will describe the challenging but immensely rewarding process of advancing our knowledge of these exoplanets to the point where they can be used to test planet formation and evolution theories. Ultimately, I aim to characterize a novel sample of long-period giant exoplanets that will enable unprecedented comparative investigations with the Solar System.
HOPP for High Contrast Imaging
Kristina Davis - UC-Santa Barbara
The field of direct imaging of exoplanetary systems allows astronomers to gain both photometric and spectroscopic analysis of these exoplanetary systems, more fully characterizing those systems than is possible by other indirect detection methods (e.g. radial velocity or transit detection). High contrast imaging (HCI) from ground based telescopes has begun to explore nearby, very bright and massive exoplanets at large separations from their host star, but breakthroughs are needed to advance the technology of the adaptive optic (AO), coronagraphic, and detector systems, as well as post-processing analysis techniques to classify a statistically significant number of exoplanets, especially with lower brightness, proximity, and angular separation from their host stars than has been previously achieved.
The imaging contrast ratio between a star and exoplanetary companion achievable by a direct imaging, AO system is in part set by the calibration of the amplitude and phase response of the focal plane to the AO's deformable mirror (DM) position.With the advent of Kinetic inductance detector (KID) cameras, we can better calibrate the DM/focal plane response with a technique I will introduce called the Heterodyne Optical Phase Probe (HOPP). HOPP measures the phase change of an incoming heterodyne signal incident on the KID array as the DM is actuated. The phase of the optical signal is a sensitive measurement of the optical path length of the system, and thus we can precisely characterize the DM surface shape per actuator command. By measuring the phase response, we can improve our models of the DM surface shape under a variety of optical conditions, and have a better calibration of how to scale the offset positions we feed the DM when performing speckle nulling.
Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization Array
Josh Dillon - UC Berkeley
21 cm cosmology promises a revolutionary new probe of the astrophysics and cosmology of the Cosmic Dawn and the epoch of reionization (EoR). Realizing that promise requires overcoming daunting calibration challenges to detect a small signal buried buried under foregrounds orders of magnitude brighter. In this talk, I will discuss our progress with the Hydrogen Epoch of Reionization Array (HERA), a purpose-built interferometer for 21 cm cosmology currently under construction in South Africa. I will focus on how we are using HERA's internal degrees of freedom from redundant baseline measurements to calibrate the array and ensure separability between foregrounds and cosmological signal.
The Forest AND the Trees: Bridging the multi-scale physics of star formation
Chris Faesi - University of Massachusetts - Amherst
The conversion of interstellar gas into stars provides energy, momentum, and chemical enrichment that drive the evolution of galaxies across cosmic time. Historically, observational limitations have made the star formation process (and in particular its dependence on environment) difficult to understand holistically due to the large dynamic range in scales across which it operates. However new cutting edge observational facilities are now moving the field from case studies to big data, enabling us to measure the molecular gas and young stellar distribution at very high resolution across the entire disks of a statistical significant sample of galaxies. This allows us for the first time to directly investigate how the small scale (< 100 pc) physics of star formation couples to large scale (1-10 kpc) galactic dynamics and environment. I will highlight recent and current progress my collaborators and I have made towards connecting star formation to galactic environment, including resolved studies of extragalactic molecular clouds, new methods for deriving star formation rates, and the use of dust attenuation as a tracer of the star-forming interstellar medium.
The Power and Limitations of Surface Brightness Fluctuations of Dwarf Galaxies for the Next Generation of Wide-Field Imaging Surveys
Johnny Greco - The Ohio State University
The new generation of wide-field imaging surveys will uncover thousands of diffuse dwarf galaxy candidates beyond the Local Group. Reliable distances will be required to confirm the nature of these candidates and to study their numbers and physical properties as a function of environment. Surface brightness fluctuations (SBF) offer a powerful method for measuring galaxy distances using imaging data alone, making it one of the most promising tools for finding and studying dwarf galaxies with current and future wide-field surveys. I will present a detailed study of both the power and limitations of the SBF method in the low surface brightness dwarf galaxy regime. Using realistic image simulations in which galaxies are built star-by-star, I will show the dependence of SBF on stellar mass (with incomplete sampling of the IMF), image resolution (seeing), and galaxy distance. Completing the galaxy census in the nearby universe at very low stellar mass (and generally low surface brightness) will provide some of the most stringent tests of galaxy formation and evolution in LCDM. Therefore, pushing the limits of SBF and understanding what to do when it fails will be essential as we move into the LSST/WFIRST era of wide-field astronomy.
The High-altitude Balloon Project
Sten Hasselquist - University of Utah
As part of my NSF AAPF I launch high-altitude (~100,000 ft) balloon experiments with students from the University of Utah REFUGES program, a collaboration between the university and local communities that provides academic mentoring and STEM learning experiences to middle- and high-school students from underrepresented minority groups, particularly those from refugee families in the Salt Lake City area. To date, we have successfully launched two experiments that were tasked with measuring the temperature and pressure of Earth's atmosphere as a function of time. In this talk I discuss this project and present our results. I also describe future improvements to this program, and how we plan to increase its effectiveness and sustainability.
A Census of Blue Stragglers in Open Clusters with Gaia DR2
Emily Leiner - Northwestern University
Blue stragglers are stars found in clusters that are brighter and bluer than the main sequence turnoff. These stars form through binary interactions, often via binary mergers or mass transfer. Gaia astrometric measurements have now enabled kinematic memberships of open clusters across the sky, allowing us to identify blue straggler populations in many poorly studied clusters. I will present a new census of blue straggler populations in a sample of nearby (< 3 kpc) open clusters based on Gaia DR2 membership information. This sample has enabled the best study to date of blue straggler production rates across a range of cluster parameters. We find the number of blue stragglers increases significantly with cluster age. I will present this sample, compare these observations with population synthesis models of clusters, and discuss how these results can inform our understanding of blue straggler formation.
PEAS: The Planet as Exoplanet Analog Spectrograph
Emily Martin - UCSC
Exoplanets are abundant in our galaxy and yet characterizing them remains a technical challenge. Solar System planets provide an opportunity to test the practical limitations of exoplanet observations with high signal-to-noise data that we cannot access for exoplanets. However, data on Solar System planets differ from exoplanets in that Solar System planets are spatially resolved while exoplanets are unresolved point-sources. I will present a novel instrument designed to observe Solar System planets as though they are exoplanets, the Planet as Exoplanet Analog Spectrograph (PEAS). PEAS consists of a dedicated 0.5-m telescope and off-the-shelf optics, located at Lick Observatory. PEAS uses an integrating sphere to disk-integrate light from the Solar System planets, producing spatially mixed light more similar to the spectra we can obtain from exoplanets. In my talk, I will discuss the general system design and science goals of the PEAS instrument.
PCA based algorithm for image reconstruction and model fitting for the EHT
Lia Medeiros - Institute for Advanced Study
The Event Horizon Telescope (EHT), a mm-wavelength very long baseline interferometer (VLBI), published the first image of a super massive black hole at event horizon scale resolution in April 2019. This first image is of the black hole in the center of M87, but the EHT has also observed the black hole in the center of our own galaxy, Sagittarius A* (Sgr A*). Sgr A* poses a significant challenge to image reconstruction and model fitting efforts since this source is expected to exhibit rapid variability in the structure of the emission region (see e.g., Medeiros et al. 2017, 2018a,b). I will discuss a novel image reconstruction algorithm based on Principal Component Analysis (PCA) that aims to reconstruct both still images and time-dependent animations. This algorithm will also allow for detailed comparisons between variable observations and time-dependent models.
The Star Formation Properties of Extremely Metal-Deficient Dwarf Galaxies in the Local Universe
Jacqueline Monkiewicz - Arizona State University
Extremely metal-deficient (XMD) galaxies, with nebular oxygen abundances of less than one-tenth the Solar abundance, are a rare class of nearby dwarf galaxies commonly treated as Local analogs for early protogalaxies-- despite the presence of underlying evolved stellar populations and [alpha/Fe] ratios consistent with multiple prior generations of star formation.
Using radio continuum observations from the JVLA and a custom set of optical emission line filters, I examine applicability of locally-derived global star formation laws at extreme metallicities. I estimate the completeness of current XMD samples within 100 Mpc, and examine the spatial distribution of XMDs within the Local Volume (D < 11 Mpc). I find that XMDs are preferentially located along the edges of large-scale filaments and superclusters. I conclude that the combination of both efficient outflows and unenriched inflows is necessary to account for all of the properties of XMDs in the nearby universe.
The multi-dimensional interstellar medium of the Small Magellanic Cloud
Claire Murray - Johns Hopkins University
Interstellar gas in the nearby Small Magellanic Cloud (SMC) has been violently disrupted by ongoing dynamical interactions with the Large Magellanic Cloud and the Milky Way halo. Nevertheless, the radial velocity field of SMC gas looks like a simple rotating disk, from which we have inferred its basic physical properties such as mass and halo composition. However, the rotating disk model has never been directly tested, as spectral line tracers constrain only the line of sight velocities. I will present recent efforts to unravel the SMC mystery by providing the first constraints for its 3D gas kinematics. By comparing Gaia proper motions of massive, young stars embedded within the HI to model predictions, I will show that SMC gas is inconsistent with rotation and is likely made up of overlapping structures. I will then discuss incoming observations with the Hubble Space Telescope, which will help us to constrain the 3D structure of gas throughout the SMC to complete our multi-dimensional view of the structure and properties of gas within the system.
Neutral Hydrogen in the CGM of Nearby Galaxies
Amy Sardone - The Ohio State University
The ongoing deep HI survey, IMAGINE (Imaging Galaxies' Intergalactic and Nearby Environments), probes the diffuse, extended neutral hydrogen gas around 28 galaxies within 20 Mpc. With the Parkes Radio Telescope, we have mapped this diffuse gas to unprecedented column density sensitivity and have quantified the amount of neutral gas inside the virial volume of these galaxies. I will discuss some early science results from this survey including depletion timescales, signs of accretion from the IGM, and new HI structures revealed in the galaxies' CGM.
Toward an understanding of neutrino flavor mixing in core-collapse supernovae
MacKenzie Warren - North Carolina State University/Michigan State University
With that advent of neutrino detectors, the detection of neutrinos from the next galactic core-collapse supernova (CCSN) has become almost a certainty. However, most modern simulations of core-collapse supernovae still do not include neutrino flavor mixing, due to uncertainties in the fundamental physics and limited computational resources. The role of neutrino flavor mixing in the explosion mechanism and the expected observed neutrino signal from a nearby CCSN event are thus not fully understood. I will present our current effort to include the effects of neutrino flavor mixing into the FLASH supernova code using an approximation to the full quantum kinetic equations. I am able to reproduce known neutrino flavor mixing phenomena and have begun to explore how neutrino flavor mixing occurs in dense environments. I will also discuss the prospects of what can be learned about flavor mixing from observations of the next galactic CCSN.
Discovery of a massive, infrared-dark galaxy at z~5-6 in a tiny ALMA survey
Christina Williams - University of Arizona
Extragalactic surveys have revealed that massive galaxies evolved rapidly in the early Universe, halting their star-formation as early as 2 billion years after the Big Bang. Still, the astrophysics behind their rapid growth and early death are longstanding problems in our theoretical understanding of galaxy formation. I will discuss the recent discovery of infrared-"dark" galaxies with ALMA, a new and likely abundant population of massive dust-obscured galaxies at z>4 that have been missed by current deep extragalactic surveys. Dark galaxies are a missing link in our picture of massive galaxy growth, and represent a preview of discoveries to come with the upcoming James Webb Space Telescope.