MN Institute for Astrophysics Colloquium

semester, 2018


Friday, January 5th 2018
Speaker: No colloquium this week.

Friday, January 12th 2018
Speaker: No colloquium this week.

Friday, January 19th 2018
Speaker: No colloquium this week.

Friday, January 26th 2018
Speaker: No colloquium this week.

Friday, February 2nd 2018
Speaker: No colloquium this week.

Monday, February 5th 2018
Speaker: Jeff Pedelty, NASA
Subject: Jeff will share his diverse experiences while working for NASA and its industrial partners.

Jeff earned a B.S. in physics from the Iowa State University in 1981 and a Ph.D. in astrophysics from the University of Minnesota in 1988. His thesis combined observational radio astronomy with Professor Rudnick and computational fluid dynamics with Professor Woodward. Since leaving Minnesota he has worked for NASA’s Goddard Space Flight Center in Greenbelt, MD. He supported the Nobel-winning Cosmic Background Explorer (COBE), the Earth science missions Landsat 7, 8, and 9, and the Joint Polar Satellite System (JPSS-1) weather satellite. He also worked in the areas of high performance computing, signal and image processing, astrobiology, and remote sensing science. For the past 10 years he has worked for the Landsat Project onsite at Ball Aerospace in Boulder, CO and at Orbital ATK in Gilbert, AZ.


Friday, February 9th 2018
Speaker: Terry Jones, University of Minnesota
Subject: Interstellar Polarization

This talk will start with a bit of retrospective on my career in astronomy, after which I will focus on the topic of interstellar polarization. I will concentrate on work done here at the University of Minnesota, up to current work using MMTPol on the MMT and HAWC+ on SOFIA. The primary science goal of this work is to study the magnetic field geometry in all phases of the interstellar medium, and determine what limitations there are to that effort. Lastly, I will describe some future trends.


Friday, February 16th 2018
Speaker: Evan Skillman, MIfA
Subject: The Resolved Stellar Populations JWST Early Release Science Program

Our JWST ERS program will obtain deep multi-band NIRCam and NIRISS imaging of three resolved stellar systems within 1 Mpc. We will use this broad science program to optimize observational setups and to develop data reduction techniques that will be common to JWST studies of resolved stellar populations. We will combine our expertise in HST resolved star studies with these observations to design, test, and release point spread function (PSF) fitting software specific to JWST. PSF photometry is at the heart of resolved stellar populations studies, but is not part of the standard JWST reduction pipeline. Our program will establish JWST-optimized methodologies in six scientific areas: star formation histories, measurement of the sub-Solar mass stellar IMF, extinction maps, evolved stars, proper motions, and globular clusters, all of which will be common pursuits for JWST in the local Universe. Our observations will be of high archival value (e.g., for calibrating stellar evolution models, measuring properties of variable stars, and searching for metal-poor stars) and will provide blueprints for the community to efficiently reduce and analyze JWST observations of resolved stellar populations.


Friday, February 23rd 2018
Speaker: Attila Kovacs (SAO)
Subject: Far-infrared frontiers

The far-infrared (FIR) and (sub)millimeter bands provide us with unique views of structure formation in the Universe and the Galaxy alike. At these wavelengths we have the most adept probes of active star-formation that sample almost all of the reionized Universe (z~1--10) with essentially no bias. The Sunyayev Zel'dovich effect traces the assembly of galaxy clusters regardless of cosmological distance. Locally, in the Galaxy, FIR polarimetry probes the magnetic environments and dust properties around optically obscured young stars and cores, while FIR spectroscopy can spy on the ices in planetary disks. I will also highlight some of the ground-braking recent and upcoming instrumentation and technologies I work on to can deliver this scientific treasure trove.


Friday, March 2nd 2018
Speaker: Dr. Mateusz Ruszkowski, U. Michigan
Subject: The role of cosmic rays in stellar and supermassive black hole feedback

I will discuss the role of cosmic rays in stellar and supermassive black hole feedback. I will argue that cosmic rays are likely to play a very important role across a large range of distance scales -- from the scales of individual galaxies to the scales comparable to those of cool cores of galaxy clusters.

Regarding the galactic scale feedback, I will focus on supernova and cosmic ray driven winds. Galactic outflows play an important role in galaxy evolution and, despite their importance, detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. Although cosmic rays comprise only a tiny fraction of interstellar particles by number, they carry energy comparable to that in the thermal gas. I will describe a suite of global 3D MHD numerical simulations that focus on the dynamical role of cosmic rays injected by supernovae, and specifically on the impact of cosmic ray transport along the magnetic fields. Our results show that this microphysical effect can have a significant impact on the wind launching depending on the details of the plasma physics.

Regarding the feedback on galaxy cluster scales, I will discuss results from our simulations of black hole jets in cool cores of galaxy clusters including the effects of cosmic rays. I will argue that cosmic ray heating of the intracluster medium (ICM) may be a very important heating mechanism both in the tenuous and cold phases of the ICM while not violating observational constraints.

While largely an unexplored territory in the context of galactic winds and AGN feedback, cosmic ray feedback is an important process facilitating launching and efficient driving of galactic-scale winds in starburst galaxies and heating of the ICM and remains the subject of intense research.

Faculty Host: Thomas W. Jones

Friday, March 9th 2018
Speaker: David Sand, U. Arizona
Subject: Unveiling the Physics and Progenitors of Cosmic Explosions with a One Day Cadence Supernova Search

Supernovae (SNe) are a linchpin for understanding the chemical evolution and star formation history of the Universe. Despite progress, some of the most basic questions about SNe persist, and we seek to answer the question: What are the explosion mechanisms and progenitor star systems of SNe? In the early hours to days after explosion, SNe provide clues to how they explode, and what their
progenitor star systems were. Observing these ephemeral signatures requires a fast search cadence and immediate spectroscopic response, a dual feat which has been difficult to achieve. Motivated by the need to discover, and study, SNe within the first day of explosion, we have begun a one-day cadence SN search of nearby galaxies (D<40 Mpc; also known as the DLT40 Survey) with a PROMPT 0.4-m telescope directly tied to the robotic FLOYDS spectrographs, a pair of instruments that I helped to develop. Here I will highlight our team's initial discoveries, with an eye towards what will be achievable with future time domain
surveys -- perhaps including nearly automated follow-up of LSST transients and Advanced LIGO gravitational wave events with the suite of Steward Observatory's small telescopes.

Faculty Host: M. Claudia Scarlata

Friday, March 16th 2018
Speaker: No colloquium this week - Spring Break

Friday, March 23rd 2018
Speaker: Dr. Jordan Stone, U. Arizona
Subject: Thermal Infrared Probes of Exoplanetary Systems with LBTI

Understanding the gas-giant planet formation process is confused by the fact that it appears multiple formation routes produce objects a few times the mass of Jupiter, where the low-mass tail of the stellar mass function and the high-mass tail of the planet mass function overlap. Distinguishing the formation route for particular objects is challenging but important to create the clean samples necessary to constrain both the planet formation process and the tail-end of the star/brown dwarf-formation process. In particular, constraining the disk-based planet formation mechanism for gas-giants is important because their dynamical dominance affects the formation of terrestrial and ice-giant planets. System architecture and atmospheric composition both provide formation indicators for gas-giants because disk-based formation results in non-hierarchical orbits and atmospheric metal enrichment, as seen in Jupiter and Saturn. I will discuss two programs which I lead with LBTI to probe the outer architecture of planetary systems and to characterize the atmospheres of gas-giant exoplanets. I will also provide an update on the LBTI HOSTS survey for exozodiacal dust around nearby stars. HOSTS is nearing completion and will provide essential information for the design of future space missions that aim to image habitable zone terrestrial planets in reflected light.

Faculty Host: Charles E. Woodward

Friday, March 30th 2018
Speaker: Lou Stolger, Space Telescope
Subject: The Rates of Supernovae, Far and Near

For nearly two decades, the Hubble Space Telescope has been heavily used to locate supernovae in high redshift environments, with the primary goal of improving constraints on the nature of dark energy. Along the way we have made surprising observations on the nature of supernovae themselves, and clues to their elusive progenitor mechanisms, some of which are difficult to reconcile with observations at much lower redshift. From complete volumetric supernova rate histories that now extend to z > 2 we find type Ia supernova delay-time distributions are consistent with a power law index of -1, but with the fraction of prompt (t_d < 500 Myr) is less than expected from various ground-based surveys. Core collapse supernova rates trace the cosmic star formation rate history, but require stellar progenitors more massive than has been seen in deep studies of nearby events (M > 20 M_sol). I’ll detail some interesting discoveries from our recent campaigns on clusters of galaxies, and also discuss what we expect to find with the James Webb Space Telescope, launching in 2018, and with WFIRST in the 2020s.


Friday, April 6th 2018
There will be no colloquium this week.

Friday, April 13th 2018
Speaker: No speaker this week.
Faculty Host: M. Claudia Scarlata

Friday, April 20th 2018
Speaker: No colloquium - See info for the Kaufmanis Public Lecture on the 18th

Friday, April 27th 2018
Speaker: Dr. Christian Veillet, Large Binocula Telescope Observatory (LBTO)
Faculty Host: Charles E. Woodward

Friday, May 4th 2018
Speaker: Dr. Silvia Protoppa, U. Maryland
Subject: Probing the Formation and Evolution of the Solar System Through Compositional Analysis

Over the past decade, the synergy of ground- and space-based observations, modeling efforts, and laboratory studies has highlighted vital information on the composition of solar system bodies. I will discuss some of the latest results from New Horizons at Pluto and contrast them with emerging trends seen in other trans-Neptunian objects and comets – the primitive remnants of the planetesimal disk from which the outer planets formed. I will demonstrate how characterizing the composition of these objects, which requires performing laboratory measurements and applying advanced modeling techniques to interpret state-of-the-art ground- and space-based observational data, improves our understanding of the primordial solar nebula and the accretion processes that led to the formation of the planets. I will also outline future work and perspectives in light of recent results.

Faculty Host: Charles E. Woodward

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