// Enter speaker information here. The format is:
//
// ["Date","Name","Affiliation","Title","Abstract","Day","Time"]
//
// In the Abstract field you must escape double quotes (\"). Some HTML
// is possible (like <br>, <b>, etc.).
//
// ** Edited to add color change for special day/time.
// ** If Day or Time field is not empty, special day/time
// ** is/are added in date column in red.
//
February[0]=["2","Timothy Brandt","Institute for Advanced Study","Discovering and Characterizing Exoplanets with High-Contrast Spectroscopy","Advances in adaptive optics and infrared instrumentation now enable us to see young exoplanets millions of times fainter than their host stars.  By collecting photons emitted by these worlds, imaging allows us to measure the chemistry and physical states of their atmospheres.  Now, a new generation of experiments is combining upgraded adaptive optics with integral-field spectrographs (IFSs) to discover and characterize fainter worlds closer to their host stars.  I will present the results of recent high-contrast surveys and the scientific promise of this new generation of instruments, with a particular focus on the CHARIS IFS for the Subaru telescope.  CHARIS will be the only instrument of its class in the northern hemisphere and will have the broadest spectral coverage of any high-contrast IFS; it will provide unique sensitivity to close-in exoplanets and present new data analysis challenges.  CHARIS is now being built and will begin operations this summer.  It will commence its first two year, 20 night survey in early 2017, taking spectra of giant exoplanets and searching about 100 stars for new companions.","",""];

February[1]=["9","Sebastian Heinz","University of Wisconsin at Madison","In the ring with Circinus X-1 - a multi-round find to understand a stubbornly unusual X-ray binary","","",""];

February[2]=["16","Lynne Hillenbrand","California Institute of Technology","Young Star Fundamentals and Surprises","","",""];

February[3]=["23","Nadia Zakamska","Johns Hopkins University","Observations of Quasar Feedback","","",""];

March[0]=["1","James Wray","Georgia Institute of Technology","Pushing the limits of remote spectroscopy to infer planetary surface compositions","","",""];

March[1]=["8","Rachel Rosen","Columbia University","A Massive Gravity Primer","The predictions of General Relativity (GR) have been confirmed to a remarkable precision in a wide variety of tests. In addition, consistent and well-motivated modifications of the theory of GR have been notoriously difficult to obtain.  However, in recent	years a compelling modification has been shown to be free of the traditional pathologies.  This is the theory of massive gravity, in which the graviton has a small mass.  In this talk I will give a general review of massive gravity, discuss potential observational signatures and present the current challenges facing this theory.","",""];

March[2]=["15","Lorenzo Sironi","Harvard Center for Astrophysics","The Journey of High-Energy Photons in Blazar Jets","We investigate the origin and the fate of high-energy photons in blazar jets, by means of first-principles particle-in-cell (PIC) kinetic simulations. In magnetically-dominated jets, magnetic reconnection is often invoked as a mechanism to transfer the jet magnetic energy to the emitting particles, thus powering the observed non-thermal emission. With 2D and 3D PIC simulations, we show that magnetic reconnection in blazar jets satisfies all the basic conditions for the emission: extended non-thermal particle distributions (with power-law slope between -2 and -1), efficient dissipation and rough equipartition between particles and magnetic field in the emitting region. In addition, relativistic magnetic islands generated by reconnection can power the ultra-fast bright flares observed from a number of TeV blazars. TeV photons from blazars will interact in the intergalactic medium (IGM) with the extragalactic background light, producing a dilute beam of ultra-relativistic pairs. It is a matter of recent debate whether the energy of the pair beam is lost due to inverse Compton scattering off the CMB -- resulting in ~10-100 GeV photons -- or heats the IGM via collective plasma instabilities. The astrophysical stakes are very high because of the large amount of energy and extensive cosmic volume involved in this process. We study the relaxation of blazar-induced beams in the IGM, by means of 2D and 3D PIC simulations. We find that at most 10% of the beam energy is deposited into the IGM plasma, so that at least 90% of the beam energy will be ultimately re-processed in the multi-GeV band.","",""];

March[3]=["22","Ryan Hickox","Dartmouth University","The Hidden Monsters: Obscured AGN in the era of NuSTAR and WISE","The study of powerful, highly obscured accreting black holes has recently seen dramatic advances with hard X-ray observations from NuSTAR and mid-infrared data from WISE. These 'hidden' obscured quasars were for a long time elusive, but we can now identify millions of these objects across most the sky, and characterize the nature of their obscuration and their role in the formation of galaxies. I will describe a few recent efforts to characterize the star formation rates, dark matter halo masses, and level of obscuration in these 'hidden' AGN, and present evidence that (at least some) powerful obscured quasars represent an evolutionary phase in the evolution of their host galaxies, as predicted by models of galaxy formation.","",""];

March[4]=["29","Ryan Foley","University of Illinois at Urbana-Champaign","The Most Common 'Peculiar' Supernova","In the last decade, transient surveys have identified several new types of supernovae (SNe). These new events represent astrophysical phenomena that are either less luminous or rarer than the more prevalent classes of SNe Ia, II, Ib, and Ic. I will discuss a relatively new class, Type Iax supernovae (SNe Iax). These events are observationally similar to SNe Ia, but are physically distinct being less luminous and having lower kinetic energy. To date, ~60 clear members of the class have been identified, making them the most common (by number) peculiar class of supernova. After accounting for their luminosity, there are roughly 30 SNe Iax for every 100 SNe Ia in a given volume, also making SNe Iax the most common peculiar SN by rate and more common than SNe Ib. I will describe observations of individual members of the class and those of the entire class, which suggests that SN Iax progenitors are likely a C/O white dwarfs that accrete material from non-degenerate helium star companions. The explosion is likely a sub-sonic deflagration, and at least some of the time the white dwarf does not completely disrupt, leaving a remnant with particular observational signatures. I will also present Hubble Space Telescope observations of three SNe Iax. For one SN, in pre-explosion images, we have detected its progenitor system, which is most consistent with being the predicted C/O WD-He-star system. This is the first detection of a thermonuclear SN progenitor system. For another SN, in images taken 4 years after explosion, we detect a source consistent with being a puffed up remnant star. If true, this would represent a new class of objects, of which there may be a handful in the Milky Way.","",""];

April[0]=["5","Marco Velli","UCLA","Coronal Heating and Solar Wind Acceleration: the Roles of MHD Turbulence and Fast Reconnection","","",""];

April[1]=["12","Angela Olinto","University of Chicago","The Extreme Energy Cosmic Frontier","","",""];

April[2]=["19","Peng Oh","University of California at Santa Barbara","Characteristic Scales in the CGM and IGM","","",""];

April[3]=["26","Andrew MacFadyen","New York University","Moving Mesh Simulations of Binary Black Hole Accretion and Relativistic Jets","I will discuss novel `moving mesh' techniques for numerical hydrodynamics and present recent simulations exploring the dynamics and observational signatures of two topics: 1) accretion onto binary black holes and 2) relativistic jets. The centers of nearly all galaxies are now known to host super-massive black holes with masses of millions to billions times the mass of the Sun. As galaxies merge with each other over cosmic history these black holes are expected to fall to the center of the new merged galaxies and form binary systems of two black holes in orbit around each other. The black holes can merge with each other in the presence of gaseous accretion flows and are prime candidates for simultaneous observations of both gravitational waves and electromagnetic signals. I will present the results of 2D hydrodynamical simulations of circum-binary accretion disks using the new moving-mesh code DISCO.  In the second part of my talk I will discuss the dynamics of relativistic jets propagating through surrounding gaseous environments. I will demonstrate that jet breakout from the surface of a star or ejecta cloud naturally results in the production of long lived X-ray transients similar to the plateaus observed in X-ray light curves of GRBs.","",""];

May[0]=["3","Laura Lopez","Ohio State University","Investigating the Symmetry, Progenitors, and Particle Acceleration of Supernova Remnants","Although supernovae (SNe) are routinely detected through dedicated robotic surveys, but most of these SNe are often too distant (~1-100 Mpc) to resolve the SN ejecta and immediate surroundings of the exploded stars. Fortunately, supernova remnants (SNRs) offer the means to study explosions, dynamics, and particle acceleration at sub-pc scales. In this talk, I will review recent advances in the understanding of SNe based on studies of SNRs, particularly using Chandra and NuSTAR X-ray observations. I will highlight investigations of SN asymmetry, based on morphologies and heavy metal (like iron and titanium) kinematics and abundances. I will also summarize the constraints on Type Ia SN progenitor scenarios using hard X-ray observations. Finally, I will present results localizing the hardest (>10 keV) non-thermal X-rays, which are associated with synchrotron emission from electrons accelerated by SNR shocks and discuss the implications regarding the particle acceleration process.","",""];

May[1]=["10","Julianne Dalcanton","University of Washington","","","",""];

September[0]=["6", "Richard Ellis", "UCL/ESO", "The Observational Quest for the Earliest Galaxies: Progress and Challenges", "", "", ""];

September[1]=["13", "", "", "No Colloquium", "", "", ""];

September[2]=["20", "Anna Frebel", "MIT", "A Single Prolific r-process Event Preserved in an Ultra-faint Dwarf Galaxy", "The heaviest elements in the periodic table are synthesized through the r-process, but the astrophysical site for r-process nucleosynthesis is still unknown. The major current candidates are ordinary core-collapse supernovae and neutron star merger. Ancient, metal-poor ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that provides the means to study clean signatures of nucleosynthesis events, and thus, can yield unique information on the origin of these processes. Previously, extremely low levels of neutron-capture elements were found in the metal-poor stars in ultra-faint dwarf galaxies which supported supernovae as the r-process site. Based on Magellan/MIKE high-resolution spectroscopy, we have determined chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II. Seven stars display extremely enhanced r-process abundances, comparable only to the most extreme r-process enhanced metal-poor stars found in the Milky Way's halo. The enhancement is also 2-3 orders of magnitude higher than that of stars in any of the other ultra-faint dwarfs. This implies the neutron-capture r-process material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae but consistent with that of a neutron star merger. This would be the first signature of a neutron star merger in the early universe which holds the key to finally identifying the r-process production site. Furthermore, such a single r-process event is a uniquely stringent constraint on the metal mixing and star formation history of this ultra-faint dwarf galaxy.", "", ""];

September[3]=["27", "Volker Springel", "HITS", "Hydrodynamical Simulations of Galaxy Formation: Progress, pitfalls, and promises", "", "", ""];

October[0]=["4", "Dmitri A. Uzdensky", "Univ. Colorado Boulder and IAS", "Frontiers of Radiative Plasma Astrophysics: Powering the Brightest Gamma-ray Flares by Relativistic Magnetic Reconnection", "Many high-energy astrophysical sources — pulsars, PWN, magnetars, GRBs, and AGN (including blazar) jets  — produce bright bursts of gamma-ray emission, often featuring rapid variability and nonthermal spectra. This calls for a powerful and efficient mechanism of particle acceleration to very high relativistic energies within a collisionless plasma environment. One of the most promising basic plasma processes for this is magnetic reconnection — a rapid rearrangement of magnetic field and violent release of magnetic energy. Reconnection is believed to power numerous explosive phenomena in space physics (e.g., solar flares and geomagnetic storms) and has also been invoked to explain gamma-ray flares in astrophysics. However, in contrast to conventional, solar-system examples, astrophysical reconnection processes can be affected by the radiation back-reaction on the accelerated particles. I will review the recent progress in understanding radiative magnetic reconnection — a new frontier in high-energy plasma astrophysics — including the development of our new radiative particle-in-cell code Zeltron, which self-consistently incorporates synchrotron and inverse-Compton radiation reaction, and its application to some fundamental problems in high-energy astrophysics. For illustration, I will consider the intense gamma-ray flares discovered by AGILE and FERMI in the Crab Nebula. The rapid (hours) variability and high (hundreds of MeV) photon energies in these flares challenge modern theories of astrophysical particle acceleration, in particular, by violating the standard synchrotron radiation reaction-imposed limit of about 100 MeV on the synchrotron photon energy, which holds in most traditional particle acceleration models. Using analytical arguments and Zeltron numerical simulations, I will show how relativistic magnetic reconnection can help circumvent this energy limit and thus explain the Crab flares.  Finally, I will discuss some future prospects and open questions in radiative plasma astrophysics. ", "", ""];

October[1]=["11", "Tom Murphy", "UCSD", "Challenging Einstein: Lunar Laser Ranging as an Absolute Test", "General Relativity is one of two foundational pillars of physics, yet gravity is the most weakly tested of the fundamental forces.  Using the pristine solar system as a laboratory, we bump into this pillar to see if it might fall.  This talk will describe many facets of the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) and how we can push an order-of-magnitude advance on our knowledge of fundamental gravity.  Preliminary results from a new Absolute Calibration System will be highlighted, which moves APOLLO from millimeter range precision to millimeter accuracy.", "", ""];

October[2]=["18", "Jo Dunkley", "Princeton University", "The polarized microwave background: ACTPol and beyond", "Measurements of the Cosmic Microwave Background radiation have taught us a great deal about the origins and content of the universe, but there is still more information to be extracted, teaching us about the energetic moments in the early universe, about neutrino physics, and the later-time expansion of the Universe.  I will show new results from the Atacama Cosmology Telescope Polarimeter in northern Chile, an experiment measuring the polarization of the CMB. I will then talk about the future: plans for new measurements from the ground from the Simons Observatory and the CMB-S4 experiment, and from space with the PIXIE satellite.", "", ""];

October[3]=["25", "Matthew McQuinn", "University of Washington & Institute for Advanced Study", "The Thermal Odyssey of the Photoionized Intergalactic Medium", "I will summarize the history of IGM temperature measurements from the Lyman-alpha forest as well as the theory for the IGM temperature after reionization. I will show that the simplest theory for thermal evolution, which has little parametric freedom, works remarkably well at reproducing recent measurements spanning 1.5 < z <4.5. This agreement allows little room for extra sources of heat beyond photoionization. At z > 5, large fluctuations in the opacity of the Lyman-alpha forest are observed on 100 Mpc scales (with some regions being completely opaque — these are the famous Gunn-Peterson troughs). I will show that these fluctuations at z~5.5 either indicate large spatial fluctuations in the temperature or in the ionizing background. For both possibilities, the amplitude of these fluctuations yield insights into the process of cosmological reionization: that it was quite extended (it temperature is the culprit) and that it ended at z~6 (for both). Finally, whether the IGM’s temperature suppresses gas accretion onto halos is NOT set by the Jeans’ mass at the cosmic mean density (or at the halo virial density) as models assume. I will describe an intuitive picture for how the pressure of the IGM (slowly) shuts off dwarf galaxy formation.", "", ""];

November[0]=["1", "Karin Öberg", "Harvard", "Chemistry of protoplanetary disks and nascent planets", "Exo-planets are common, and they span a large range of compositions. The origins of this compositional diversity are largely unconstrained. Among planets that are Earth-like, a second question is how often such planets form hospitable to life. A fraction of exo-planets are observed to be ‘physically habitable’, i.e. of the right temperature and bulk composition to sustain a water-based prebiotic chemistry. This does not automatically imply, however, that they are rich in the building blocks of life, in organic molecules of different sizes and kinds, i.e. that they are chemically habitable. In this talk I will argue that characterizing the chemistry of protoplanetary disks, the formation sites of planets, is key to address both the origins of planetary bulk compositions and the likelihood of finding organic matter on planets. The most direct path to constrain the chemistry in disks is to directly observe it. In the age of ALMA it is for the first time possible to image the chemistry of planet formation, to determine locations of disk snowlines, and to map the distributions of different organic molecules. Recent ALMA highlights include constraints on CO snowline locations, the discovery of spectacular chemical ring systems, and first detections of more complex organic molecules. Observations can only provide chemical snapshots, however, and even ALMA is blind to the majority of the chemistry that shapes planet formation. To interpret observations and address the full chemical complexity in disks requires models, both toy models and astrochemical simulations. These models in turn must be informed by laboratory experiments, some of which will be shown in this talk. It is thus only when we combine observational, theoretical and experimental constraints that we can hope to characterize the chemistry of disks, and further, the chemical compositions of nascent", "", ""];

November[1]=["8", "Szabolcs Marka", "Columbia", "The Future in Discovery and the Discovery in the Future", "Advanced LIGO discovered cosmic gravitational waves and surprised us with giant binary black-hole systems, just in time for the 100th anniversary of Einstein's prediction. Gravitational waves became the latest window on the Universe from violent transients to cosmology.  I will discuss some aspects of (i) the instrumental breakthroughs that enabled the unprecedented sensitivity reached by Advanced LIGO and (ii) the key scientific directions in which gravitational wave searches are being utilized in the context of multimessenger astronomy focusing on the future.", "", ""];

November[2]=["15", "Heather Knutson", "Caltech", "Exoplanet Detectives:  Seeking Clues to Explain the Diverse Architectures of Exoplanetary Systems", "Over the past two decades ongoing surveys have detected thousands of new planetary systems around nearby stars. These systems include apparently single gas giant planets on short period orbits, closely packed systems of up to 5-6 “mini-Neptunes”, and solar-system-like architectures with either one small planet or no planets interior to 0.5 AU. Despite our success in cataloguing the diverse properties of these systems, we are still struggling to develop narratives that can explain their divergent evolutionary paths.  In my talk I will describe two new promising avenues of investigation, including constraints on the compositions of short-period planets and statistical studies of the frequency of outer gas giant and stellar companions in these systems.  Taken together, these observations provide important clues that can be used to determine whether or not the observed population of short period exoplanets formed in situ or migrated in from farther out in the disk.", "", ""];

November[3]=["22", "Scott Ransom", "NRAO", "Extraordinary Physics with Millisecond Pulsars","Pulsars are some of physics and astrophysics' most exotic objects, and they have already earned two Nobel Prizes. We currently know of about 2500 of them in our Galaxy, but a small subset, the millisecond pulsars (MSPs), are truly remarkable. These systems are notoriously hard to detect, yet their numbers have more than doubled in the past 5 years via surveys using the world's most sensitive telescopes, new instrumentation, and huge amounts of computing. Specialized ''timing'' observations of these systems, accounting for each and every one of the billions of rotations of the stars, are providing fantastic results in basic physics. In this talk I'll focus on the efforts to directly detect gravitational waves from super-massive black hole binaries, make strong-field tests of general relativity, and determine the nature of the densest form of matter known in the universe.", "", ""];

November[4]=["29", "Maxim Markevitch", "GSFC, NASA", "The first high-resolution X-ray spectrum of a galaxy cluster", "During its brief period of operation, the Hitomi X-ray observatory (known as Astro-H prior to launch) has observed the Perseus galaxy cluster as a first-light target. This has been a long-awaited first look at a galaxy cluster with an X-ray calorimeter, which provided a qualitative leap in energy resolution (by factor 20-30) for extended celestial sources. Such resolution is sufficient to detect Doppler shifts and broadening of atomic lines caused by motions and turbulence in the intracluster plasma. The core of the Perseus cluster is a site where all the physical processes that govern cluster evolution combine -- runaway radiative cooling, AGN heating, large-scale sloshing of the core gas, acceleration of ultrarelativistic electrons, and interaction between the plasma and the cold molecular gas. The Hitomi spectrum is a treasure trove of emission lines from various ions that contain dynamical as well as chemical information. Our analysis reveals a rather quiescent velocity field for such a visibly disturbed object. We also did not detect the 3.5 keV emission line, considered a possible signal from the dark matter decay, at the flux previously reported by XMM (an instrument with a much lower energy resolution). I will present these and other preliminary results from the ongoing analysis of the first-ever high-resolution cluster spectrum.", "", ""];

December[0]=["6", "Eve Ostriker", "Princeton University", "Controlling Star Formation, from Clouds to Galaxies", "", "", ""];

December[1]=["13", "Frank van den Bosch", "Yale", "Dark Matter Substructure: Cosmological Treasure Trove or a Pandora's Box?", "Hierarchical structure formation in a LCDM cosmology gives rise to virialized dark matter halos that contain a wealth of subtructure. Being able to accurately predict the abundance and demographics of dark matter subhaloes is of paramount importance for many fields of astrophysics: gravitational lensing, galaxy evolution, and even constraining the nature of dark matter. Dark matter substructure is subject to tidal stripping and tidal heating, which are highly non-linear processes and therefore best studied using numerical N-body simulations. Unfortunately, as I will demonstrate, state-of-the-art cosmological simulations are unable to adequately resolve the dynamical evolution of dark matter substructure. They suffer from a dramatic amount of artificial subhalo disruption as a consequence of both inadequate force softening and discreteness noise amplification in the presence of a tidal field. I discuss implications for a variety of astrophysical applications, and briefly discuss potential ways forward.", "", ""];