Sam Waldman, MIT

The direct detection of gravitaitonal waves will provide a revolutionary new probe of the most energetic processes in the universe. The 4 km long LIGO interferometers have demonstrated the sub-attometer displacement sensitivity (< 10^{-18} m/ Hz^{1/2}) required to place upper limits on the neutron star/neutron star merger out beyond the Virgo galaxy cluster. Such mergers are thought to be the progenitors of short gamma-ray bursts and provide an ideal "golden event" signal for direct GW detection. An aggressive R&D program, Advanced LIGO, is underway to increase the interferometer stored power 30-fold (to 750 kW), develop new low noise readouts, and increase the detector sensitivity by an order of magnitude. In the next 5 years, Advanced LIGO will observe neutron star mergers and other gravitational wave events regularly, beginning a new era of gravitational astronomy.

Fred Ciesla, The University of Chicago (Geophysical Sciences)

Protoplanetary disks are dynamic objects through which mass and angular momentum are transported as part of the final stages of pre-main sequence evolution for a star. Chondritic meteorites record a dynamic history for our own solar system as they contain a variety of objects that formed in distinct physical and chemical environments, yet are intimately mixed on fine-scales. To date it remains to be determined whether models of protoplanetary disks can explain the variety of primitive materials found in our own solar system and how they came to be accreted into common meteorite parent bodies. Further, it remains unclear what stages of disk evolution identified by astrophysical models are recorded within meteorites. I will discuss these issues and argue that the earliest stages of solar nebula evolution recorded by meteorites coincide with no later than the first few hundred thousand years of our sun's formation.

Mark Krumholz, University of California - Lick Observatory

Stars are the engines of the Universe: nuclear reactions within them are the only significant source of non-gravitational power in the cosmos and the source of all heavy elements. However, the process by which stars form remains poorly understood, and one mystery in particular stands out: why is star formation so slow? In many galaxies the bulk of the interstellar medium does not participate in star formation, and in all galaxies even those clouds that are active form stars at a rate of only ~1% of their mass per dynamical time. Any successful theory of cosmic evolution must be able to explain these facts, and be able to predict how the star formation process changes with galactic environment and over cosmological time. In this talk I discuss progress toward a physical theory of star formation capable of meeting these requirements.

Nadia Zakamska, Institute for Advanced Study

Quasars are among the most powerful objects in the Universe and are now thought to play an important role in galaxy evolution. Despite their extreme luminosity, the majority of all quasars have eluded detection through conventional methods until recently. In these objects, the active regions are embedded in clouds of gas and dust, making them faint at optical, ultraviolet and X-ray frequencies, quite unlike 'normal' quasars that are bright at these wavelengths. I will present a detailed study of such obscured quasars, describe the evolution of these objects and their host galaxies and review the current status of quasar demographics studies from multi-wavelength surveys.

Enrico Ramirez-Ruiz, University of California (Lick Observatory)

Merging compact binaries are the one source of gravitational radiation so far identified. Because short-period systems that will merge in less than a Hubble time have already been observed as binary pulsars, they are important both as gravitational wave sources for observatories such as LIGO, but also as progenitors for short gamma-ray bursts. Recent progress in our understanding of these systems is outlined, emphasizing the breadth of the subject and the links with fundamental physics. An effort is made to distinguish between ideas that are already well established and those that still lie on the speculative frontiers. There are, fortunately, several feasible types of observation that could soon clarify the issues.

Maryam Modjaz, UC Berkeley

Long-duration gamma-ray bursts (GRBs) and Type Ib/c Supernovae (SN Ib/c) are two of nature's most magnificent explosions. Both can be seen over cosmological distances, and both are products of collapsing massive stars. While GRBs launch relativistic jets, SN Ib/c are core-collapse explosions whose massive progenitors have been stripped of their hydrogen and helium envelopes. Yet for over a decade, one of the key outstanding questions in astronomy is what conditions lead to each kind of explosion in massive stars. Determining the fate of massive stars is essential for using GRBs as star formation indicators over distances up to 13 billion light-years, and for mapping the chemical enrichment history of the universe.
I will present a number of comprehensive observational studies that probe the progenitor environments, their metallicities and the explosion conditions of SN with and without GRBs. Specifically, my benchmark study on the measured metallicities of SN with and without GRBs indicates that low metallicity (less than ~1/3 solar) might be the key factor for producing SN-GRBs, providing constraints on the theoretical predictions of GRB formation. Furthermore, I will discuss SN 2008D, which was discovered serendipitously in January 2008 with the NASA Swift satellite via its X-ray emission and has generated great interest amongst both observers and theorists. I will discuss the significance of this SN, whether it harbored a jet, and its implications for the SN-GRB connection. I will conclude with an outlook on how the most promising venues of research - using both existing facilities such as Magellan and innovative SN surveys, and also upcoming large-scale surveys such as LSST - will shed light on the diverse deaths of massive stars.

Mary Putman, Columbia University

Galaxies like the Milky Way form stars throughout their lifetimes at rates that indicate a continuous fuel source is needed. I will discuss the evidence for this continual fueling with a focus on gas surrounding the Milky Way. In particular, the roles of existing cold halo clouds and the extended diffuse hot halo medium are discussed in the context of local and cosmological simulations of galaxy formation.

William Cochran, McDonald Observatory, The University of Texas at Austin

The Kepler spacecraft, launched in March 2009, is designed to detect potentially habitable Earths around other stars by detecting the transits of these planets across the disks of their parent stars. This requires performing differential photometry to a precision of 20ppm on a sample of 170,000 stars for a period of 3.5 years. We will discuss the on-orbit performance of the Kepler photometer, and then present the first scientific results from Kepler. Five new transiting planets around solar-type stars have been discovered so far, along with several other interesting objects.

Brenda L Dingus, Los Alamos National Lab

The deepest, wide field of view survey of the TeV sky has been performed with the Milagro observatory, probing the origin of Galactic cosmic rays through discovery of new Galactic gamma-ray sources, diffuse Galactic gamma-ray emission, and unexpected localized regions of hadronic cosmic rays. Milagro was located near Los Alamos, NM and was operated from 2000-2008. A next-generation version of this wide field of view, high duty cycle, water Cherenkov observatory is called HAWC. HAWC will be located near Puebla, Mexico at an elevation of 13,500' and will have 15 times the sensitivity of Milagro. I will discuss results from Miilagro and the expected contributions of HAWC.

Gregory Laughlin, University of California Santa Cruz

The past year has seen enormous advances in our understanding of extrasolar planets. In this talk, I'll focus on some of the most exciting recent highlights. These include (i) the discovery and characterization of remarkable new transiting planets, (ii) a complete upending of the conventional wisdom regarding the statistics of the galactic planetary census, and (iii) a new method for actually looking inside certain transiting planets.

Andrew Gould, Ohio State University

Microlensing planet searches have discovered a total of 17 planets, including the first Jupiter-Saturn like system and the only 4 "cold Neptunes" yet detected. The discovery process is almost unbelievably chaotic, with the so-called "high-magnification events" being the most chaotic. I show, nevertheless, that the high-magnification subsample constitutes a "controlled experiment",
which enables rigorous statistical analysis, yielding important new clues to planetary architecture. I also discuss the future potential of microlensing to explore domains of planet parameter space not probed by any other method.

Andrea Lommen, Franklin and Marshall College

NANOGrav is a consortium of radio astronomers and gravitational wave physicists whose goal is to detect gravitational waves using an array of millisecond pulsars as clocks. Whereas interferometric gravitational wave experiments use lasers to create the long arms of the detector, NANOGrav uses earth-pulsar pairs. The limits that pulsar timing places on the energy density of gravitational waves in the universe are on the brink of limiting models of galaxy formation and have already placed limits on the tension of cosmic strings. Pulsar timing has traditionally focused on stochastic sources, but most recently I have been investigating the idea of detecting individual gravitational wave bursts wherein there are some interesting advantages. I will also demonstrate how the array can be used to reconstruct the waveform and obtain its direction.

Kollmeier Juna, Carnegie Institution of Washington

The Milky Way provides an opportunity for a close-up investigation of the complex processes of galaxy and star formation. I will discuss recent efforts to do this by using rare, but important, probes of these phenomena. In the first portion of the talk I will present results on hypervelocity stars primarily from the Sloan Digital Sky Survey. The distribution of these stars, in physical properties and in space, allows us to place interesting limits on star formation and dynamics at the Galactic Center as well as the possibility to constrain the shape of the Milky Way's dark matter halo. I will discuss progress we have made toward these goals. In the second portion of the talk, I will discuss how one can use RR Lyrae stars to probe the outer halo of the Milky Way and find new and distant substructures which are difficult to probe by other means. Our recent confirmation of a distant structure in RR Lyrae stars highlights the power of this approach to unraveling the outer halo and showcases exciting possibilities for future all-sky time-domain surveys.

Jeter Hall, Fermi National Laboratory

There is a large body of evidence that ~85% of the matter in the Universe is in the form of cold, non-baryonic dark matter. I describe how terrestrial particle detectors are searching for clues on the nature of the dark matter. I focus on two leading experiments, current results, and challenges in searching for an unknown form of matter.

Zeljko Ivezic, University of Washington

Despite a several thousand years long history, sky surveying is experiencing a bonanza as detectors, telescopes and computers become ever more powerful. I will discuss how the unprecedentedly accurate and diverse data from the optical Sloan Digital Sky Survey have recently enabled numerous exciting discoveries. I will use three specific examples (asteroids, quasar variability, and mapping of the Milky Way stellar distribution) to give a preview of what to expect from the upcoming next-generation surveys, such as the Dark Energy Survey and the Large Synoptic Survey Telescope.

Paolo Gondolo, University of Utah

The first stars in the universe may have shined due to dark matter annihilation instead of nuclear fusion. They were dark matter-powered stars, or for short Dark Stars. In this talk, I will report on the story of Dark Stars including recent developments: how they formed, evolved and might have died, and how they might be detected.

James Kasting, Pennsylvania State University

Over 400 planets have been found around nearby stars, but none of them is thought to be at all like Earth. The goal now is to identify rocky planets within the habitable zones of their stars and to search their atmospheres spectroscopically for signs of life. To do this, we need new space-based telescopes such as NASA’s proposed Terrestrial Planet Finders or ESA’s Darwin mission (all of which are indefinitely postponed at the moment). If spectra of extrasolar planet atmospheres can be obtained, the presence of O2, which is produced from photosynthesis, or O3, which is produced photochemically from O2, would under most circumstances provide strong evidence for life beyond Earth. But “false positives” for life may also exist, and these need to be clearly delineated in advance of such missions, if at all possible. I will also contrast my optimism about the search for complex life with the more pessimistic view expressed by Ward and Brownlee in their book, Rare Earth.

Adam A Lidz, University of Pennsylvania

A key period in our story of structure formation is the Epoch of Reionization (EoR), when early populations of galaxies and/or quasars formed, emitted ultraviolet light and ionized 'bubbles' of gas around them, eventually filling the entire volume of the intergalactic medium (IGM) with ionized gas. Reionization studies aim to determine the filling factor and size distribution of ionized bubbles during the EoR, which in turn constrain the properties of the first luminous sources. Current observations suggest that hydrogen is reionized sometime before z>~6 by star-forming galaxies. These sources should simultaneously singly ionize helium, but are unlikely to also doubly ionize it. Helium may be doubly-ionized only later on, perhaps near z~3, by bright quasars. I will describe efforts to theoretically model the Epochs of Hydrogen and Helium Reionization, and focus on some of their observational implications. First, I will forecast the prospects for learning about hydrogen reionization from upcoming 21 cm observations. I will then discuss an analysis of existing HI Ly-a forest data aimed at identifying signatures of helium reionization near z~3.

Scott A. Hughes, MIT

A simple problem in Newtonian gravity, the motion of two bodies about one another is far more challenging in general relativity (GR). Motivated largely by the anticipated importance of compact binaries as gravitational-wave sources, many years of effort have produced a suite of tools for modeling binaries with GR. In this talk, I will present an overview of how we model these sources in GR and what we have learned from the relativistic two-body problem. I will focus in particular on how unique aspects of relativistic gravity flavor the gravitational waves which binaries generate, and how these flavorings can be exploited to learn about compact bodies, especially black holes. I will emphasize analogs between the GR analysis and electromagnetic theory, hopefully demonstrating that the rich features of these models are in fact surprisingly intuitive.

Brian Fields

The lifespans of the most massive stars are a symphony of the fundamental forces, culminating in a spectacular and violent supernova explosion. While these events are awesome to observe, they can take a more sinister shade when they occur closer to home, because an explosion inside a certain "minimum safe distance" would pose a grave threat to the biosphere on Earth or elsewhere. We will discuss these cosmic insults to life, and ways to determine whether a supernova occurred nearby over the course of the Earth's existence. We will then present recent evidence that a star exploded near the Earth about 3 million years ago. Radioactive iron-60 atoms have been found in ancient samples of deep-ocean material, and are likely to be debris from this explosion. Recent data confirm this radioactive signal, and for the first time allow sea sediments to be used as a telescope, probing the nuclear reactions that power exploding stars. Furthermore, an explosion so close to Earth was probably a "near-miss," which emitted intense and possibly harmful radiation. The resulting environmental damage may even have led to extinction of species which were the most vulnerable to this radiation.

Robert P. Kirshner, Harvard-Smithsonian Center for Astrophysics

Supernova have been developed into a powerful tool for cosmological distance measurement. In the (recent) past, supernovae showed that we live in an accelerating universe. In the present supernovae are a key element in constraining the properties of dark energy. While the present data are consistent with a cosmological constant, today's constraints are not very rigorous. As a community, we are beginning to learn where the systematic problems arise in tightening the noose and improving our knowledge. I'll review some of the problems we have encountered with dust absorption and supernova environments and I will show some promising developments using thermonuclear supernovae in the near-infrared that may mitigate these difficulties. The future will not be as easy as the past, but the conclusion of programs like ESSENCE, Supernova Legacy Survey and the Sloan Supernova Survey plus the Palomar Transient Factory, Pan-STARRS, and the Dark Energy Survey all promise real progress in the years just ahead.

Eric Feigelson, Penn State

High-resolution X-ray observations of star forming regions show that magnetic reconnection flares are powerful and frequent in pre-main sequence solar-type stars. Well-defined samples in the Orion Nebula Cluster and Taurus clouds exhibit flares with peak X-ray luminosities L_x ~ 1e29-1e32 erg/s, orders of magnitude stronger and more frequent than contemporary solar flares. X-rays are emitted in magnetic loops extending 0.1-10 stellar radii above the stellar surface and thus have a favorable geometry to irradiate the protoplanetary disk. The fluorescent FeK 6.4 keV emission line and X-ray absorption directly indicates X-ray irradiation of cold material in some young systems; this is supported by observations of infrared lines from ionized neon and excited molecules from the outer disk layers. A tail of penetrating hard X-rays with energies ~10-30 keV is sometimes present.

There is thus considerable empirical evidence that X-rays from the host star irradiate protoplanetary disks, heating and ionizing their outer layers, and likely penetrating to the midplane in some disk regions. As ionization fractions need only reach ~ 1e-12 to induce the magnetorotational instability and associated turbulence, X-rays may be the principal determinant of the extent of the viscous `active zone' and laminar `dead zone' in the layered accretion disk. It may be important for the dissipation of gas in older disks via photoevaporation. X-ray irradiation may thus play a major role in planet formation processes: whether particle growth occurs by settling or in turbulent eddies; whether turbulence inhibits rapid inspiral from headwinds; whether protoplanets suffer secular migration or random walk interactions; whether transition disks are quickly dissipated. The violent magnetic flares from young stars may also explain shock melting of chondrules and a spallogenic origin of some anomalous short-lived radioisotopes found in ancient meteorites.

Eric Blackman, University of Rochester

Many, if not all, post-AGB stars rapidly transform from spherical to a powerful aspherical pre-planetary nebula (pPN) outflow phase before presumably fading into a less powerful planetary nebula (PN). The pPNe outflows require engine rotational energy and a mechanism to extract this energy into collimated outflows. Just radiation and rotation are insufficient, but an interplay between rotation, differential rotation and magnetic fields seems promising, not unlike the presumed symbiosis of these ingredients in other jetted sources. Present observational evidence for magnetic fields in evolved stars is suggestive of dynamically important magnetic fields, but both theory and observation are rife with opportunity. I will discuss why magnetohydrodynamic (MHD) shaping and launch might arise in pPNe and PNe. Scenarios involving binary driven dynamos and accretion engines cannot yet be ruled out. One noteworthy paradigm involves accretion onto the primary post-AGB white dwarf core from a low mass companion whose decaying accretion supply rate powers the asymmetric pPN. Strategies for distinguishing different engine mechanisms is a topic of active research. The related physics of dynamos and accretion disks underpins MHD launch and shaping scenarios throughout astrophysics and I will summarize some progress and challenges in our evolving understanding of the underlying principles.

Ellen Zweibel, U Wisconsin-Madison

Despite spectacular recent progress in cosmology, the origin of magnetic fields in the Universe remains unknown. I will review the evidence, emphasizing recent detections of extremely weak intergalactic fields, discuss the evolution of these fields over time, and talk about their effects on astrophysical processes.

Joshua Eisner, University of Arizona

Planetary systems form out of disks of dust and gas that are remnants of the star formation process. The structure of these protoplanetary disks within 1 AU of their central stars has important implications for terrestrial planet formation, giant planet migration, and disk accretion. I will present spatially and spectrally resolved observations of gas and dust within 1 AU of young stars, with a focus on hydrogen gas at stellocentric radii smaller than a tenth of an AU. I will describe the new instrumentation and techniques that enabled these measurements, and discuss the resultant constraints on star and planet formation processes.

Todd Hossbach, Pacific Northwest National Laboratory

Coherent neutrino-nucleus scattering is a non-controversial prediction of the Standard Model of Particle Physics that has yet to be experimentally verified. In the first part of the talk I will discuss a new research effort to search for this elusive process at a spallation source using a small CsI(Na) detector. I will show how this detector can be easily scaled to a size relevant for studies of fundamental neutrino properties and discuss its potential as a supernova-neutrino detector. The second part of the talk will focus on exploiting the coherent scattering process and a new type of low-noise large-mass germanium detector to monitor the emission of antineutrinos from operating nuclear reactors. Details of this new germanium detector will be presented and I will discuss how this technology has allowed us to perform one of the most sensitive light-WIMP searches thus far.

Raymond Pierrehumbert, The University of Chicago

On 2010 September 30, Vogt et al. reported the detection of two new planets orbiting the M-dwarf star Gliese 581. One of these two planets, 581g, is in what is loosely known as the "habitable zone," where a planet can support an Earth-like climate given a suitable atmosphere. I will discuss the factors governing whether this potentially habitable planet is indeed habitable, and the prospects for detecting whether the planet actually has an atmosphere which would render it habitable.

Chuck Steidel, Caltech

During the peak epoch of galaxy formation, the intergalactic medium is both the source of gas fueling star formation in forming galaxies, as well as the waste dump for the products of star formation and black hole accretion that are not retained by galaxies. By studying the "Circum-Galactic Medium", the region within a few hundred physical kpc of forming galaxies, one can begin to constrain the flow of baryons into and out of galaxies. At present, there is a puzzling discrepancy between observations and theoretical expectations whose resolution may be the key to unraveling the aspects of galaxy formation that are least well-understood.

Eve Ostriker, University of Maryland

Star formation rates depend on both the total available interstellar gas mass and the physical state of that gas and the local galactic environment -- including the stellar and dark matter gravitational potentials. In a multiphase disk, the relative proportion of mass in gravitationally bound clouds vs. the diffuse ISM depends on energy injected by star formation. This energetic feedback both heats gas and drives turbulence, and it can lead to a self-regulated star-forming state. I will discuss recent numerical work showing that multiphase, turbulent ISM simulations are able to reproduce observed star formation rates, provided that the disks' vertical structure is resolved down to ~pc scales. These results are also consistent with empirical relationships that have been found between midplane pressure and the star formation rate (or molecular gas fraction). I will also introduce a new theoretical model that predicts the star formation rate as a function of the total gaseous surface density and the midplane density of stars + dark matter. This prediction derives from requirements for maintaining thermal and dynamical equilibrium in the diffuse gas. In HI-dominated outer-disk regions, star formation rates increase until the thermal pressure in the two-phase ISM matches the dynamic pressure. In the central regions of galaxies, the total surface density of HI is limited due to the high cooling rate of vertically confined, high-pressure gas. Cooling cannot exceed the heating provided by UV from young stars; this leads to a saturation of the HI surface density, consistent with observations. Application of this thermal/dynamical equilibrium theory to a set of spiral galaxies shows excellent agreement between predicted and observed star formation rates, especially for flocculent galaxies.