Events

Astronomy Seminar Series

Lindy Blackburn, Harvard-Smithsonian Center for Astrophysics

The Event Horizon Telescope (EHT) Collaboration released the first image of black hole in April of this year, opening the field of horizon-scale study of the spacetime and environments around black holes via direct imaging. The radio image, taken at a wavelength of 1.3 mm (230 GHz) and using the technique of very-long-baseline interferometry, matches that of lensed photons from relativistic magnetized plasma surrounding a 6.5 billion solar mass black hole at the center of M87.

Astronomy Seminar Series

James Wadsley, McMaster University

Different modes of stellar feedback play different roles within galaxies. We study the role of supernovae, an historically popular choice, on the evolution of galaxies and their stellar content. We argue that prior work  has modeled supernovae poorly by ignoring stellar clustering and also the key physics of conduction that governs hot gas evolution. Clustered supernovae create superbubbles, kpc-scale feedback events that can drive strong galactic winds.

Colloquium Series

Sami Mitra

Editor, Physical Review Letters (APS)

In a talk that I am hoping will quickly morph into a free-flowing Q and A session, I will discuss the role that PRL plays in disseminating your physics results. The process is a cascading sequence that entails interacting with journal editors, referees, conference chairs, journalists, department chairs, deans, funding agencies, and others. The tools, however, have changed in recent years; the arrival of social media, search engines, and electronic repositories have us in a state of flux. PRL published its first paper 60 (plus 1) years ago. Let's look back and forward.

Astronomy Seminar Series

Dragan Huterer, University of Michigan

I will give a theory-centered overview of the results from the Dark Energy Survey, an experiment mapping the large-scale structure in order to better understand the cause of the accelerated expansion of the universe. Year-1 DES analyses published in 2017/18 included the combination of galaxy clustering, cosmic shear, and their cross-correlation to impose constraints on key cosmological parameters, while the imminent Year-3 and, later, Year-6 analyses will dramatically improve those constraints.

Astronomy Seminar Series

Dominic Pesce, Event Horizon Telescope collaboration

Some accretion disks surrounding supermassive black holes in active galactic nuclei (AGN) are observed to host powerful water vapor maser emission.  These astrophysical masers -- dubbed "megamasers" because of their large luminosities relative to Galactic counterparts -- have proven to be unique tools for studying the geometry and dynamics of AGN accretion disks on sub-parsec scales, where the black hole dominates the gravitational potential.  The masing gas parcels act as test particles in thi

Astronomy Seminar Series

Doug Johnstone

We have undertaken a 4-year dedicated JCMT/SCUBA-2 monitoring program of eight nearby star-forming regions (Herczeg et al. 2017) to search for sub-mm brightness variations as a proxy of episodic accretion. In this talk I will discuss the novel methods used to reach a relative calibration of 2% (Mairs et al. 2017a) and present the first variable source found in the sub-mm with a quasi-periodic light curve, the Class I protostar EC 53 in Serpens Main (Yoo et al. 2017).

Astronomy Seminar Series

Adrienne Erickcek

As remnants of the earliest stages of structure formation, the smallest dark matter halos provide a unique probe of the density fluctuations generated during inflation and the evolution of the Universe shortly after inflation.  The absence of early-forming ultra-compact minihalos (UCMHs) establishes an upper bound on the amplitude of the primordial power spectrum on small scales and has been used to constrain inflationary models.  I will show how numerical simulations of UCMH formation reveal that these constraints need to be re

Quantum Information Seminar

Arash Ahmadi, Ph.D. Graduate Student

In this talk I will present our work on nanowire quantum dots (QDs), and discuss how proper excitation of the source can lead to an enhancement of the performance of our source. My talk will focus on generation of entangled photon-pairs in a QD embeded in a photonic nanowire. Our results indicate that, in spite of a large nuclear spin and fine-structure splitting, nanowire QDs are capable of generating dephasing-free entangled photons.

Astronomy Seminar Series

Go Ogiya

The coalescence of supermassive black holes (SMBHs) should generate the strongest sources of gravitational waves (GWs) in the Universe. However, the dynamics of their coalescence is the subject of much debate. In this study, we use a suite of N-body simulations to follow the merger of two nuclear star clusters (NSCs), each hosting a SMBH in their centre.

Astronomy Seminar Series

Matt Dobbs

Technology advances has opened a new era of radio observations. We are now monitoring the sky at millisecond cadence and discovering a vast catalog of new fast radio transients while simultaneously making deep maps of structure in the universe using hydrogen intensity mapping as a tracer.