Past Seminars

Defining and Reaching Outreach Audiences on a Budget

Michael Reid

Dunlap Institute, University of Toronto
Sep 13, 2016

MSI Seminar
MSI Conference Room

Two of the central challenges of doing public outreach are defining a target audience and reaching that audience on a limited budget. Often we let our advertising budget dictate the audience we will reach, but it doesn’t have to be this way. In this talk, I will discuss the approach we use at the Dunlap Institute to define our target audience for a program, and ensure we reach them within our budget. I’ll outline the transferrable strategies we’ve used to go from struggling to fill small auditoria to regularly attracting thousands of people to our events, all on a small-to-zero advertising budget. Plenty of time will be allowed for discussion and questions.

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Cosmology and Astrophysics from Combined Probes

Joachim Harnois-Déraps

Institute for Astronomy, University of Edinburgh
Sep 21, 2016

Astrophysics Seminar
Bell Room (103), Rutherford Building

Combining cosmological probes has emerged as a key technique in the interpretation of cosmological data, largely because it is insensitive to instrumental systematics, but also for its ability to measure new quantities that are otherwise out of reach. Particularly promising are the combination of dark matter maps extracted from the cosmic shear of galaxy surveys with similar maps reconstructed from the lensing of the Cosmic Microwave Background, and with electron pressure maps measured via the thermal Sunyaev-Zel’dovich effect. These provide new measurements of the amount of fluctuations in the matter density field, they help in selecting/rejecting baryonic feedback mechanisms currently used in hydrodynamical simulations, in addition to offering an independent re-calibration of the cosmic shear signal. The statistical noise in this measurement will decrease in the next few years, at which point we will push our measurement to smaller scales and constrain the total neutrino mass. In this talk, I will describe these different techniques, including state-of-the-art data sets, numerical simulations and theoretical modeling, and present some of the latest developments.

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From Pixels to Planets: A history of transiting extrasolar planets and first hand account of the Kepler Mission

Jason Rowe

Université de Montréal
Sep 27, 2016

MSI Seminar
MSI Conference Room

We live in an era of exoplanet discovery. It is truly astounding to look at the evolution of exoplanet research over the past few decades. We have quickly moved from discoveries of individual planets to announcing discoveries a few thousand at a time. My work has covered a wide variety of current exoplanet research that covers fundamental parameters, atmospheres and composition. I am actively involved in the immediate scientific goal to complete the statistical census of exoplanets in the inner regions (less than 1AU) of their host star and to populate the mass-radius diagram for exoplanets. I will present an overview of the history and status of transiting extrasolar planets a present an insider view of the operations and discoveries from NASA's workhouse Kepler mission. I will show how current and future facilities and instruments such as CSA-BRITE, NASA-K2, SPIRou/CFHT, NASA-TESS, JWST/NIRISS and the Thirty Meter Telescope will push exoplanet discovery space towards the characterization of planets with properties potentially similar to the Earth

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From Plasma Physics on Stars to Space Weather on Other Worlds: Why We Need to Understand Stars to Find the Next Earth

Rachel Osten

Space Science Telescope Institute
Oct 4, 2016

Astrophysics Seminar
Bell Room (103), Rutherford Building

While it has long been known that stars can produce flaring eruptions, their detailed study had been relegated to a few types of stars considered atypical of potential solar system (and life-bearing planet) hosts. I will review multi-wavelength evidence from stellar studies which cements a physical connection with solar flare processes, describe where our understanding falls short, and discuss the astrobiological implications. Next I will describe recent results on stellar flares which probe the extremities of these events and discuss how these can be used to give context to processes bounding solar flare properties. Finally I will discuss how these studies can give insight into space weather on other worlds, as astronomers expand the realm of potentially habitable worlds, and circle back to why we need to understand stars to have a hope of finding the next Earth.

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Breaking Through Exoplanetary Atmospheres

Mercedes López-Morales

Oct 11, 2016

MSI Seminar
MSI Conference Room

In the past two decades we have gone from only knowing about the planets in our own Solar System to discovering thousands of planets orbiting around other stars. We have not only discovered that planets abound, but also that most planetary systems do not resemble our own. One of the next steps in the field of exoplanets is to study their atmosphere and answer questions such as: do the physical properties of gas giant exoplanets resemble those of the Solar System giants? Are there exoplanets with atmospheres similar to Earth? In this talk I will describe the state of the art techniques we are using and developing to characterize exoplanetary atmospheres, the main results so far, and our plan for the future.

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I’m from the government and I’m here to help

David Loop

NRC Herzberg Institute of Astrophysics
Oct 18, 2016

Astrophysics Seminar
Bell Room (103), Rutherford Building

I will give an overview of the NRC Herzberg astronomy technology program, why we exist, who we are, and what we are currently involved in. I will also speak to the ways in which we engage with Canadian universities, and work through some current examples. This will include instrument collaborations, advanced technology research, and graduate student and postdoc engagements. My goal is to convince you that the cynical title is actually a reality of ways that we can work together.

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Observing Exoplanet Atmospheres

Lisa Esteves

University of Toronto
Oct 19, 2016

Special Astrophysics Seminar
MSI Conference Room

The confirmation, follow-up, and atmospheric characterization of a large number of super-Earths and smaller planets will be among the main challenges facing exoplanet researchers in the next decades. In this talk I will discuss the current state of exoplanet research and in particular what our research team is doing to study exoplanet atmospheres using ground- and space-based telescopes. We will also discuss what the future of exoplanet research holds and how we are going to get there.

Packing for Mars: Integrating biomarker and exploration field science in Earth analogue environments

Allyson Brady

McMaster University
Oct 25, 2016

MSI Seminar
MSI Conference Room

The ubiquitous nature and metabolic diversity of microbes enables survival in a wide array of environments and locations, including some of the harshest conditions on Earth. Microbial interactions with their environment can result in the creation of unambiguous signatures of life, or ‘biosignatures’. Biosignatures provide clues about the nature of the microbial communities and their influences in the geologic record on Earth, and may include organic biomarkers of cell components such as phospholipids, specific mineral morphologies, and isotopic variations. Mounting evidence for periods of liquid water on the surface of Mars suggests the possibility that there may once have been abundant microbial life. As it is likely that such life is long extinct, biosignatures represent the primary measures by which we can search for evidence that it may once have existed beyond the Earth. Analogue sites on Earth are locations with environmental, geological and/or biological conditions that are representative of early Earth or other planets (e.g. polar, geothermal). They provide a wealth of information on microbial diversity, past environmental conditions, biosignature development and the potential for preservation of such signatures in the geologic record that is used to inform space science and exploration. Real space missions come with constraints and challenges, for example life support limitations and communications delays with scientific experts back on Earth. Analogue research that combines both field science and simulated Mars operational conditions is used to assess the impacts of these constraints on scientific productivity. In this talk I will present an overview of NASA analogue projects that integrate both biomarker and exploration science to inform future space missions with an eye towards life detection and sample return.

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Galaxy Cluster Evolution over the Past 10 Billion Years

Michael McDonald

MIT Kavli Institute for Astrophysics and Space Research
Nov 1, 2016

Astrophysics Seminar
Boardroom (room 105), Rutherford Building

In recent years, the number of known galaxy clusters has grown dramatically, thanks in large part to the success of surveys utilizing the Sunyaev Zel'dovich effect. In particular, surveys like the South Pole Telescope 2500 deg2 survey have discovered hundreds of distant clusters, allowing us to trace for the first time the evolution of clusters from shortly after their collapse (z~2) to present day (z~0). In this talk, I will highlight recent efforts to understand the observed evolution in the most massive clusters, in terms of the large-scale hot intracluster gas, the cooling gas in the very center of the cluster, the most massive central galaxy, and the supermassive black hole at the very center. In addition, I will attempt summarize the current state of galaxy cluster surveys and briefly discuss the potential of next-generation surveys.

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CMB Lensing: Fundamental Physics from Maps of the Invisible

Blake Sherwin

University of California, Berkeley
Nov 8, 2016

MSI Seminar
MSI Conference Room

Dark matter not only forms an invisible cosmic scaffolding within which galaxies form, its distribution in the universe also contains a wealth of information about fundamental physics. Measurements of gravitational lensing in the cosmic microwave background (CMB) allow this matter distribution to be directly seen and mapped. In my talk, I will describe the rapid advance of CMB lensing measurements from first detections, to current work, to ultra-high-precision cosmology in the near future. I will explain how upcoming CMB lensing measurements will allow us to determine the masses of neutrinos and probe the properties of inflation and the very early universe.

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The Enigmatic Lambda Boötis Stars

Chris Corbally

Vatican Observatory
Nov 15, 2016

Astrophysics Seminar
Bell Room (103), Rutherford Building

Lambda Boötis stars have been an enigma since they were first isolated as a class in 1943. They seem part of the Sun's generation, yet they also masqueraded as an older population in the Galaxy. What gives them their unique spectral characteristics? How long do they retain these? Does where we find them make a difference? What is their connection with exoplanets and young stars? I shall relate the story so far of converting our partial answers into a full scenario.

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Dust and water ice in the Martian atmosphere

Christopher Lee

University of Toronto
Nov 22, 2016

MSI Seminar
MSI Conference Room

The Martian climate system is dominated by three major component cycles. Each involves the cycling of substances between the surface and atmosphere, with all three cycles coupled through microphysical, thermal, and radiative processes. Carbon dioxide, the main atmospheric gas, freezes onto the polar caps each winter resulting in a large surface pressure cycle, significant seasonal modification of the planetary albedo through surface ice deposition, and vapor-pressure buffering of the atmospheric thermal structure in the winter polar atmosphere. Particulate mineral dust, lifted from the surface by winds, significantly modifies the atmospheric thermal structure and amplifies the already strong asymmetry between the two solstitial seasons that is driven by a large orbital eccentricity. In extreme cases, radiative feedbacks enhance dust lifting and cause global dust storms that completely obscure the planetary surface. The long term effect of such global events can be found in changing global patterns of surface albedo. The water cycle interacts strongly with both the dust and carbon dioxide cycles, having a surface source and sink in the polar caps, and in the atmosphere nucleating onto suspended dust to form cloud ice particles. Clouds form in the atmosphere during well defined cloud seasons that are ultimately linked to the preferential availability of water during northern summer and the much cooler state of the atmosphere when the planet is nearer aphelion. As a result, water ice clouds play a key role in the radiative heating and circulation during the Martian summers and in modifying the distribution of atmospheric dust. Within this context, I will discuss efforts to capture the effect of the dust and water ice in the Martian atmosphere using General Circulation Models (GCMs) as a proxy for the real atmosphere. I will describe the processes responsible for dust lifting and water ice sublimation from the surface and their interaction within the atmosphere. Finally, I will show simulations of the Martian atmosphere using the MarsWRF GCM that includes models of these processes, and I will discuss the combined influence of aerosols on the thermal and dynamical evolution of the Martian climate system.

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Intermediate-mass black holes in globular clusters - Observations and Simulations

Nora Lützgendorf

Nov 29, 2016

Astrophysics Seminar
Bell Room (103), Rutherford Building

The study of intermediate-mass black holes is a young and promising field of research. If they exist, they could explain the rapid growth of supermassive black holes by acting as seeds in the early stage of galaxy formation. Formed by runaway collisions of massive stars in young and dense stellar clusters, intermediate-mass black holes could still be present in the centers of globular clusters, today. Our group investigated the presence of intermediate-mass black holes for a sample of 10 galactic globular clusters. We measured the inner kinematic profiles with integral-field spectroscopy and determined masses or upper limits of central black holes in each cluster. In combination with literature data we further studied the positions of our results on known black-hole scaling relations (such as M–σ) and found a similar but flatter correlation for intermediate-mass black holes. Applying cluster evolution codes, the change in the slope could easily be explained with the stellar mass loss occurring in clusters in a tidal field over its life time. Furthermore, I will present results from IFU simulations on the latest result of the globular cluster NGC6388 as well as simulations on the accretion of IMBHs from surrounding stellar winds.

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Investigating close-in exoplanet atmospheres with optical phase curves

Antonio García Muñoz

Technische Universität Berlin
Dec 19, 2016

Special Astrophysics Seminar
MSI Conference Room

Recent years have seen a rapid advancement in the characterization of exoplanets with phase curves at optical wavelengths. This progress has been enabled by the high precision achieved from space by MOST, CoRoT and Kepler, and has resulted in valuable constraints on the temperature, albedo and wind dynamics for a number of close-in exoplanets. Here, I will summarize some of that recent work, which combines techniques from astronomy and atmospheric sciences, paying special attention to the case of Kepler-7b [1], and offer a personal perspective on what can be expected in the near future. Refs: [1] García Muñoz, A. & Isaak, K.G. Probing exoplanets clouds with optical phase curves. PNAS, 112:13461-13466 (2015).

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Small Scale Structure of the Universe as seen by pulsars and FRBs

Ue-li Pen

University of Toronto
Jan 10, 2017

MSI Seminar
MSI Conference Room

I will describe recent developments in our understanding of the galaxy on scales of AU and smaller through a new technique known as Scintillometry. While once thought as turbulent down to scales of 1000km, new evidence favours the milky way described by magnetic domains with thin domain boundaries.  In addition to their own physical interest, these giant lenses allow direct mapping of the enigmatic pulsar magnetospheres. I describe past, current, and future measurements enabled by pulsar and FRB VLBI scintillometry.

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The Hidden Monsters: New Windows on the Cosmic Evolution of Supermassive Black Holes

Ryan Hickox

Dartmouth College
Jan 17, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

In the past decade, extragalactic surveys and active galactic nucleus (AGN) synthesis models have made great progress in understanding the cosmic growth of supermassive black holes. However, our picture of black hole evolution has remained incomplete, due to the challenges of detecting AGN that are highly obscured or hidden beneath the light of their host galaxies. With the advent of new resources including hard X-ray observations from NuSTAR, mid-infrared data from WISE, and new insights from theoretical models, we can now identify millions of these “ hidden” AGN across much the sky, and characterize the nature of their obscuration and their role in the formation of galaxies. I will describe recent efforts to characterize the host galaxies, dark matter halos, and level of obscuration in these "hidden” AGN, and will 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. Finally, I will point to the exciting potential for future of AGN population studies with the next generation of extragalactic surveys.

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Looking At Super-Earths Through Their Atmospheres 

Diana Dragomir

MIT Kavli Institute
Jan 24, 2017

MSI Seminar
Bell Room (103), Rutherford Building

The Kepler mission has revealed that super-Earths (planets with radii between 1 and 4 R_Earth) are the most common class of planets in the galaxy, though none are known to exist in our own Solar System and little is known about how they form. These planets can theoretically have a wide range of compositions which we are just beginning to explore observationally. The relative faintness of the exoplanet host stars in the Kepler field means that atmospheric characterization with currently available instruments is extremely challenging for the majority of known super-Earths. However, a handful of transiting super-Earths are within reach of existing facilities. We have pointed the Hubble and Spitzer Space Telescopes toward these systems in an effort to paint a thorough picture of their atmospheres, with some help from ground-based facilities. I will review the current state of knowledge for these super-Earths, and discuss how transmission and emission spectroscopy allows us to constrain their composition and formation history, as well as explore the transition region between terrestrial planets and miniature gas giants. The TESS mission will discover many more small planets transiting bright stars and amenable to follow-up observations. By probing the atmospheres of the few accessible super-Earths we know of now, we will inform the direction to be taken by future atmospheric studies of this class of exoplanets, in particular as enabled by the upcoming JWST and ELTs.

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Frontiers in Massive Stellar Death

Sean Couch

Michigan State University
Jan 31, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

Core-collapse supernovae are the luminous explosions that herald the death of massive stars.  While core-collapse supernovae are observed on a daily basis in nature, the details of the mechanism that reverses stellar collapse and drives these explosions remain unclear.   While the most recent high-fidelity simulations show promise at explaining the explosion mechanism, there remains tension between theory and observation.  I will discuss the recent developments in the study of the supernova mechanism that could lead to a predictive theory of massive stellar death.   In particular, I will describe our efforts to develop more realistic initial conditions for supernova simulations with fully 3D massive stellar evolution calculations.  Such realistic 3D initial conditions turn out to be favorable for successful explosions, in large part because they result in stronger turbulence behind the stalled supernova shock.  I will also discuss the important role turbulence is playing in the supernova mechanism and what might be required for accurately modeling the turbulence in our simulations.  I will also mention recent work aimed at explaining the origin of pre-supernova outbursts from massive stars in the months and years prior to core collapse and explosion.

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The Crab Nebula: The Inner Knot and flares

Maxim Lyutikov

Purdue University
Feb 2, 2017

Special Astrophysics Seminar
MSI Conference Room

We can probe observationally and reproduce theoretically the most detailed properties of the Crab Nebula nearest to the pulsar- The Inner Knot. The tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock that efficiently accelerates particles. We develop a model of  particle acceleration during explosive reconnection events in relativistic highly magnetized plasma and apply the model to explain the Crab gamma-ray flares. We argue that magnetic reconnection is an important, and possibly dominant process of particle acceleration in high energy astrophysical sources.

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The Puzzles of Very Faint X-ray Transients

Craig Heinke

University of Alberta
Feb 14, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

The evolution and final fate of low-mass X-ray binaries (LMXBs) are difficult to model, due to the wide range of physics that must be included (from common envelopes, to radiative efficiency, to the transition from neutron star LMXBs to millisecond pulsars). Simple calculations indicate that the majority of LMXBs should have short orbital periods (<~3 hours) and low mass-transfer rates, which suggest they should have infrequent, short, low-luminosity outbursts.  Such outbursts are difficult to observe with current X-ray monitoring missions (which are generally not sensitive enough at typical Galactic distances), or with pointed X-ray telescopes (due to their small field of view). However, long-term monitoring of the Galactic Center (by Degenaar, Wijnands, Muno, etc.) has revealed a population of very faint X-ray transients with peak luminosities of 10^35-10^36 ergs/s. This suggests that the expected population of old LMXBs may have been found, though their location in the crowded, heavily extincted Galactic Center prevents follow-up to identify the donor stars and characterize the systems. We have just been awarded a large Swift proposal, the Swift Galactic Bulge Survey, to survey 16 square degrees of the Galactic Bulge every two weeks for ~8 months, which should find ~15 new very faint X-ray transients. Through multiwavelength follow-up (possible at the lower typical extinctions of our survey), we should be able to identify their natures. This will help resolve key questions about how the LMXB population ages, including the transition of NS LMXBs to millisecond pulsars, and whether black hole LMXBs become more radiatively inefficient at short orbital periods, enabling them to “disappear".

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Deep Earth volatile inventories and the formation of the Moon

Rita Parai

Washington University in St. Louis
Feb 25, 2017

MSI Seminar
Redpath Museum

The deep Earth is a significant storage reservoir for volatiles, such as water, carbon dioxide and the noble gases. Noble gases in mantle-derived rocks provide unique insights into the evolution of planetary volatile budgets. Volatiles are lost from the mantle in association with volcanism, but are potentially recycled into the mantle via subduction in association with plate tectonics. We measured noble gas isotopic compositions in a suite of mid-ocean ridge basalts with sufficient precision to demonstrate that atmospheric heavy noble gases are recycled to the deep mantle over time. Although significant atmospheric xenon (Xe) recycling occurs, the Xe isotopic compositions of mantle sources have not been entirely overprinted. Rather, these preserve a record of very early differentiation of the upper mantle from the mantle plume source. I will discuss new constraints from noble gases on the nature of the plume source and upper mantle, volatile cycling between deep Earth and surface reservoirs, and the timing of the Moon-forming giant impact.

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Direct mass measurements of trans-fermium nuclei with MRTOF-MS: Toward identification of superheavy elements via mass spectroscopy

Yuta Ito

Riken Research Institute
Feb 28, 2017

Special Astrophysics Seminar
Bell Room (103), Rutherford Building

Precision mass measurements of unstable nuclei, providing direct measure of the nuclear binding energy, are invaluable for nuclear structure study and have potential for particle identification of atomic nuclide by the precision mass value. For trans-fermium nuclei, of importance for understanding the shell evolution in heavy nuclear system to inspect mass models toward so-called "island of stability" proposed by G.T. Seaborg in 1960s and the unique identification during new elements search, the mass measurements require fast measurement time even for such a heavy mass nuclei and high efficiency to tolerate extremely low production yields. Direct mass measurements of trans-fermium nuclei were, so far, performed for only 6 nuclei of nobelium and lawrencium with the Penning trap mass spectrometer SHIPTRAP Recently we implemented a multi-reflection time-of-flight mass spectrograph (MRTOF-MS) located after a cryogenic helium gas catcher and a multiple ion trap system coupled with the gas-filled recoil ion separator GARIS-II and performed direct mass measurements of wide range of actinide isotopes and mendelevium isotopes for the first time. Using 48Ca beam on natTl target, we produced 249-251Md by fusion-evaporation reaction and successfully measured those masses including new masses of 249-250Md with sub-ppm mass precision. They were extracted as doubly charged atomic ions from the gas cell as well as other actinides such as nobelium and fermium. Combined with known alpha decay Q-value of 249-250Md, we could newly determine masses of isotopes on the decay chain from berkelium to meitnerium.

Cosmology from the Stratosphere: A search for primordial gravitational waves, and measurements of gravitational lensing from near space

William Jones

Princeton University
Mar 7, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

Recent advances in the capabilities of stratospheric scientific balloons provide unique opportunities for cosmology and astrophysics. This talk will describe these capabilities, with a focus on two ongoing research programs that are designed to realize the scientific potential of this platform. Spider is a millimeter wavelength polarimeter designed to probe for the signature of primordial gravitational waves in the polarization of the Cosmic Microwave Background. During the inaugural Antarctic Long Duration flight in 2015, it was the most sensitive polarimeter ever built.I will describe the experiment, the flight and the status of the cosmological analysis. SuperBIT is a sub-arcsecond resolution, wide-field imaging telescope operating in six bands between 300-900 nm. During the course of a 100-day, mid-latitude, super pressure balloon flight SuperBIT will provide 230 mas multi-band imaging of hundreds of galaxy clusters, allowing a well characterized measure of the mass-observable relationship with tight control over systematics.

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A Story of Stellar Nurseries

Nia Imara

Harvard-Smithsonian Center for Astrophysics
Mar 15, 2017

MSI Seminar
Bell Room (103), Rutherford Building

All stars are observed to form in molecular clouds (MCs). Since these “stellar nurseries” set the stage for star formation in the Milky Way and other galaxies, astronomers would like to understand how they form and evolve. In this presentation, I will discuss different ways of investigating the environments and evolution of MCs. Millimeter observations, for example, show that local and extragalactic MCs have systematic velocity gradients, possibly indicating the large scale of rotation of clouds. In my study of MCs in the Milky Way and M33, I demonstrate that any viable theory of cloud formation must agree with a number of interesting trends pertaining to cloud kinematics. For instance, I find that many clouds may be counter-rotating with respect to overall galactic rotation, which has important consequences for theory and galactic simulations. I will also discuss how investigating both the dense gas and diffuse gas associated with MCs—via far-infrared and 21-cm observations—provides unique insight into how these environments evolve and eventually form stars.

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Short-Duration Gamma-Ray Bursts and the Electromagnetic Counterparts of Gravitational Wave Sources

Edo Berger

Harvard-Smithsonian Center for Astrophysics
Mar 21, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

Gamma-ray bursts are the most luminous and energetic explosions known in the universe. They appear in two varieties: long- and short-duration. The long GRBs result from the core-collapse of massive stars, but until recently the origin of the short GRBs was shrouded in mystery. In this talk I will present several lines of evidence that point to the merger of compact objects binaries (NS-NS and/or NS-BH) as the progenitor systems of short GRBs. Within this framework, the observational data allow us to determine the merger rate of these systems as input to Advanced LIGO, to infer the electromagnetic properties of gravitational wave sources, and to study r-process nucleosynthesis.

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Exotic Climates on Exo-Earths

Kristen Menou

University of Toronto, Scarborough
Mar 28, 2017

MSI Seminar
Bell Room (103), Rutherford Building

Recent discoveries of terrestrial planets in the habitable zone of our nearest stellar neighbors raise the prospects of the atmospheric characterization of habitable exo-worlds. I will discuss the climates of habitable zone exo-Earths, in particular the possibility of water-trapping and the long-term stability of habitable climates. As with hot Jupiters over the past decade, climate modeling of exo-Earths will guide observational efforts and provide a framework to interpret the data soon to be collected on these planets.

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Digging into the Large Scale Structure: From the galaxies to the cosmic web

Shirley Ho

Carnegie Mellon University
Apr 6, 2017

Astrophysics Seminar
Bell Room (103), Rutherford Building

Galaxy spectroscopic surveys provide the means to map out this cosmic large-scale structure in three dimensions, furnishing a cornerstone of observational cosmology. The information is given in the form of galaxy locations, and is typically condensed into a single function of scale, such as the galaxy correlation function or power-spectrum. However, galaxy correlation functions are not the only information those surveys provide. One of the most striking features of N-body simulations is the network of filaments into which dark matter particles arrange themselves. We however traditionally only use the information contained in the positions of the galaxies, and in some occasions, we look at other cosmic structures of the Universe such as voids.

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How to add, how to subtract, and how to despeckle

Eran Ofek

Weizmann Institute of Science
Jun 12, 2017

Special Astrophysics Seminar
MSI Conference Room

I present optimal methods for image coaddition and subtraction that have many advantages over existing methodolgies.These methods are useful for many types of astronomical data analysis, beyond the field of image processing. Specifically,these techniques are optimal for any hypothesis testing or measurements, numerically stable and result in data product which have uncorrelated noise. I will present these methods as well as their impact for deep surveys, transientssearch, and diffraction-limited imaging.

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Searching for dark matter in the Milky Way: current results and perspectives

Francesca Calore

Aug 15, 2017

Special Astrophysics Seminar
MSI Conference Room

Discovering dark matter is one of today's biggest challenges of particle physics and cosmology. In particular, indirect dark matter detection aims to discriminate the flux of final stable particles produced by particle dark matter annihilation or decay from the dominant background induced by astrophysical processes. I will present the state-of-the-art of dark matter searches in the Milky Way, focusing on the Galactic center, one of the most promising — and exciting — targets for dark matter identification and progresses in our understanding of the so-called Galactic center GeV excess.

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