TELECONNECTIVITY

 

Last month the climatologist Justin Maxwell from Indiana University gave an interesting talk at our department about drought-busting tropical cyclones. In his talk, and in conversations before and after with our physical geography crew, he had some interesting things to say about climate teleconnections involving mainly sea surface temperature and pressure patterns such as ENSO, NAO, etc. If teleconnections and the various acronyms are unfamiliar, check out the National Climatic Data Center’s teleconnections page: http://www.ncdc.noaa.gov/teleconnections/

SOUTH PARK & GEOMORPHOLOGY

 

I got a few e-mails last week about fluvial geomorphology—not because of anything I have done, or any current issues or unresolved questions in that field. No, it was because a character in the irreverent Comedy Central show South Park was identified on the show as a fluvial geomorphologist. Apparently that gives us a measure of popular culture street cred.

South Park character Randy Marsh, in his pop singer Lorde disguise.

An actual geomorphologist named Randy (R. Schaetzl, Department of Geography, Michigan State University).

 

Astro Seminar: Surprising New Insights into Quasars from the WISE Satellite

Abstract:
We now believe that every large galaxy hosts a supermassive black
hole at its core, with masses ranging from millions to billions of
times that of our Sun. At times, these black holes are actively
accreting, causing the nuclei of the galaxies to shine brightly
across the electromagnetic spectrum. However, in many, perhaps
most quasars, obscuring material along the line of sight shields
us from directly viewing the inner nucleus. This obscuring material
is heated, and emits strongly in the mid-infrared. The Wide-field
Infrared Survey Explorer, or WISE, has recently mapped the entire
sky in mid-infrared light with exquisite depth and clarity. WISE
has allowed us to find luminous quasars across the whole sky due
to this heated material, more than tripling the number of quasars
known. I will discuss several surprising new insights into quasars
that have come out of this work. In brief, the dominant paradigms
do not match our observations, with potentially important implications
for the role of quasars in the growth of galaxies. I will conclude
by discussing how these studies will be further enabled by the
Euclid and WFIRST satellites.

Date:
-
Location:
CP179
Event Series:

Condensed Matter Seminar: Constraints on topological order in Mott insulators

The hunt for anyonic excitations in quantum magnets is frustrated by the absence of any order parameter that could be used to detect such phases. Consequently a very important ally is the Hastings-Oshikawa-Lieb-Schultz-Mattis theorem for 2D quantum magnets, which guarantees that a fully symmetric gapped Mott insulator must be topologically ordered, though is silent on which topological order is permitted. After introducing the HOLSM theorem,  I will explain a new line of argument that constrains which topological order is permitted in a symmetric gapped Mott insulator. For example, I'll show that a fully symmetric magnet with S = 1/2 per unit cell cannot be in the double-semion topological phase. An application of our result is to the Kagome lattice quantum antiferromagnet where recent numerical calculations of entanglement entropy indicate a ground state compatible with either toric code or double semion topological order. Our result rules out the latter possibility.
 
Date:
-
Location:
CP179
Event Series:
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