Scott Tremaine, Institute for Advanced Study
They came from outer space: Planet X and 'Oumuamua
I will describe the history, the observational constraints on, and the theoretical motivations for a hypothetical Planet X beyond Neptune. I will also review the conclusions and the unresolved puzzles arising from the recent discovery of an interstellar asteroid/comet, ʻOumuamua.
Avery Broderick, Professor, Waterloo Centre for Astrophysics
Revealing Black Holes
Black holes remain one of the most dramatic, and enigmatic, predictions of general relativity. These have long been implicated as the engines of active galactic nuclei that are responsible for reshaping their hosts. This past April, the Event Horizon Telescope released the first image of a black hole horizon opening a new window onto these objects. I will summarize how this image was generated and what it means.
Patrick Hall, Professor, York University
Mining the Sky with Spectroscopy: The Maunakea Spectroscopic Explorer
The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of massively multiplexed spectroscopic surveys at both low and high resolution in the near-ultraviolet, optical, and near-infrared. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include: (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution; (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe; (iii) insights into inflationary physics and neutrino masses through a cosmological redshift survey probing a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more.
Michel Fich, Professor, Waterloo Centre for Astrophysics
CCAT-prime: an ultra-wide-field submillimeter telescope for surveys.
We are currently constructing CCAT-prime, a 6-meter aperture submillimetre/millimeter wave telescope that uses an off-axis crossed-Dragone design to achieve an extremely wide field-of-view (FoV).
Very high surface accuracy and an excellent site at 5600 meter elevation in the Atacama regions of northern will allow this telescope to deliver extremely high surface brightness sensitivity. Combined with the wide FoV this will give CCAT-prime unrivalled mapping speed and enable a wide range of goals in science areas including cosmology, fundamental physics, and galaxy and star formation and evolution. In this talk I will present a summary of the telescope and instrument properties, the current status of the project and an outline of the surveys planned for this new facility.
Pauline Barmby, Professor, Western and Bryan Gaensler, Professor, University of Toronto
The Canadian Astronomy Long Range Plan 2020-2030
The Long Range Plan co-chairs, Pauline Barmby and Bryan Gaensler, will give an overview of the status of LRP2020, and will lead a discussion on the core issues and decisions facing the Canadian astronomy community for the next decade.
Neil Turok, Director Emeritus, Perimeter Institute
The Future of Cosmology
Abstract: TBD
Julio Navarro, Professor, University of Victoria
Core qualms: reassessing the evidence against CDM
I plan to review the state of various scenarios that intend to address the "cusp vs core" controversy in dwarf galaxies. These scenarios include revisions to CDM predictions from either baryonic physics, or from changes to the nature of dark matter. I will focus, in particular, on the strength of the evidence against CDM from the diversity of rotation curve shapes and from the sinking times of Fornax globulars.
Elena Massara, Postdoctoral fellow, Waterloo Centre for Astrophysics
Weighting neutrinos with novel probes
In this talk I will discuss a fairly new probe, the marked power spectrum, and motivate why it can be use as a cosmological probe. In particular, I will describe why it is powerful tool to weight neutrinos with future surveys. I will then present a fisher matrix analysis performed with the Quijote simulations to estimate the constraining power of different marked power spectra.
Kristi Webb, PhD Student, Waterloo Centre for Astrophysics
‘Dead’ galaxies in the GOGREEN survey
Galaxies in dense clusters experience environmental quenching processes in addition to the secular processes which affect field galaxies. The timescale of the quenching processes can be used to constrain the physical mechanisms which suppress star formation. With the Gemini Observation of Galaxies in Rich Early Environments (GOGREEN) survey, we have collected a sample of ~500 spectra of quiescent galaxies, half of which are members of clusters, at 1 < z < 1.5 when the star formation rate was twice as high as it is today. We explore the differences of the populations, as a function of both environment and mass, through modelling their star formation histories and comparing spectral features. In combination with existing observations at lower redshifts, we will establish the role of large scale structure in these populations through the last two-thirds of the age of the universe.
Go Ogiya, Postdoctoral fellow, Waterloo Centre for Astrophysics
Dynamical aspects of dark matter subhalos
In the scenario of the hierarchical structure formation in the Universe, mergers between cosmic structures, such as galaxies, galaxy clusters and their surrounding dark matter (DM) halos is one of the main drivers for their dynamical evolution. Various physical mechanisms non-linearly couple with each other and work all together in the merging process. Cosmological N-body simulations have been utilized as the primal tool to investigate the complicated processes of the formation and evolution of DM halos and had tremendous success in reproducing the observations of the cosmic large scale structures. However, recent studies suggested that DM subhalos may be artificially disrupted in current state-of-the-art cosmological simulations.
In fact, this has been discussed as the over-merging problem in the past. We call up this classical problem. First, we analytically study various physical mechanisms which may disrupt subhalos and find that they cannot explain the subhalo disruptions in cosmological simulations. Secondly, using a large set of idealized N-body simulations varying numerical parameters, we identify two mechanisms for the artificial disruptions, relating to the spatial and mass resolutions of the simulations, and find two criteria to assess the reliability of the mass evolution of subhalos in the simulations. Thirdly, we make a public database of idealized N-body simulations of the tidal evolution of subhalos with sufficiently high resolutions that can be used to calibrate semi-analytical models and to complement cosmological simulations. We will also present galaxy merger simulations, reproducing the observation of the ultra diffuse galaxy of the significant DM mass deficit.
Beatrice Bonga, Postdoctoral Researcher, Perimeter Institute
Tidal resonance in EMRIs
We show the existence of a new type of resonance in extreme mass-ratio inspirals (EMRIs): tidal resonance, which is induced by the tidal gravitational field of nearby stars or stellar-mass black holes. Tidal resonance can be viewed as a general relativistic extension of the Kozai-Lidov resonances in Newtonian systems and is distinct from the transient resonance known for EMRI systems. Tidal resonances will generically occur for EMRIs. By probing their influence on the phase of the EMRI waveform, we can in principle extract information about the environmental tidal field of the EMRI system, albeit at the cost of a more complicated EMRI waveform model.
Moritz Munchmeyer, Senior Postdoctoral Researcher, Perimeter Institute
Machine Learning in cosmology
Machine learning in cosmology is a rapidly developing field that could allow us to deal with the non-linear physics and large amounts of data of upcoming precision experiments. I will give a brief overview of recent work in this domain, and then discuss in particular how machine learning can be used for a basic but important task in the analysis of statistical fields, Wiener Filtering. We show how a neural network can be trained to perform extremely fast approximate Wiener filtering of CMB maps. We propose an innovative neural network architecture, which guarantees linearity in the data map but is non-linear in the mask. Our method does not require Wiener filtered training data, but rather learns Wiener filtering from tailored loss functions, and we discuss how the choice of the loss function affects training performance. Wiener filtering is the computational bottleneck in many optimal CMB analyses, and I discuss how neural networks could be used to improve them.
Mike Hudson, Professor, Waterloo Centre for Astrophysics
Galaxies and Dark Matter Seen Through a Gravitational Lens
The evolution of galaxies is linked to the growth and accretion histories of their host dark matter haloes. Weak gravitational lensing allows us to measure the evolution of their dark matter haloes, as well as the larger cosmic web that these haloes inhabit. I will review recent results from weak gravitational lensing and other methods that allow us to probe the dark matter content of the Universe on the scale of galaxies and so provide new insight into the processes that shape the evolution of galaxies. I will also discuss our recent detection of dark matter in the filaments of the cosmic web between galaxies. I will conclude by highlighting prospects from upcoming ground-surveys, and satellite missions.