Events at Physics |
Events During the Week of March 26th through April 2nd, 2017
Monday, March 27th, 2017
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Plasma Shocks
- Time: 12:00 pm - 12:55 pm
- Place: 2317 Engineering Hall
- Speaker: Dr. Paul Drake, University of Michigan, USA
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm - 1:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Amol Upadhye (aupadhye@wisc.edu). - Host: Amol Upadhye
- Faculty Candidate Seminar
- How to find dark matter
- Time: 2:30 pm - 3:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Dr. Bjoern Penning, University of Bristol
- Abstract: Dark Matter (DM) is a long standing puzzle in fundamental physics and the goal of a diverse research program. I will review the evidence for DM and how to search for it. Underground and astrophysical searches attempt to detect DM particles in the cosmos directly or by searching for their decay products while particle colliders attempt to produce DM in the laboratory. Each of these detection methods probe different parts of the parameter space with complementary sensitivity in mass, interaction type, and uncertainties. I will show the connection between these searches, theoretical developments that connect their search strategies and how an interdisciplinary effort can probe the entire natural phase space in the near term future.
Tuesday, March 28th, 2017
- Chaos & Complex Systems Seminar
- 2016 Polling in Nation and State: A scorecard
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Charles Franklin, Law and Public Policy and Director of the Marquette University Law School Poll
- Abstract: How did the pre-election polls of 2016, at both national and state levels, perform? What did we learn about the dynamics of the campaign and the issues affecting public polling? How accurate were the polls and were some methods better than others?
- Host: Clint Sprott
- Theory Seminar (High Energy/Cosmology)
- Cosmology from Non-Linear Weak Lensing
- Time: 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Zoltan Haiman, Columbia Univ
- Abstract: Several large astronomical surveys have either been proposed or are underway to measure weak lensing distortions of up to a billion galaxies. This will allow accurate measurement of the lensing shear field in the small-scale, non-linear regime, where non-Gaussian features can contain significant cosmological information. I will report on results from a large suite of ray-tracing N-body simulations in different cosmologies, and discuss constraints from the number counts of lensing peaks (i.e. from the number of maxima as a function of their height), and from other statistics probing the non-linear<br>
regime. These statistics can tighten cosmological constraints by a factor of two, compared to using two-point statistics alone. A recent application of this approach to the CFHTLenS survey has confirmed this for the parameters (Omega_m,sigma_8). I will comment on the theoretical and simulation challenges for larger lensing surveys in<br>
the future. - Host: Joshua Berger
Wednesday, March 29th, 2017
- No events scheduled
Thursday, March 30th, 2017
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Micro-X: A Sounding Rocket Dark Matter Search
- Time: 2:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Antonia Hubbard, Northwestern
- Abstract: The Micro-X sounding rocket uses a Transition Edge Sensor (TES) array to make X-ray observations. The improved energy resolution of TESs compared to traditional space-based X-ray detectors brings new precision to both supernova observations and the X-ray search for sterile neutrino dark matter. Current X-ray observations disagree over the potential presence of a 3.5 keV X-ray line consistent with a sterile neutrino interaction, and Micro-X is in a unique position to establish or refute the presence of this line. We present the construction status of the instrument and expectations for flight observations, with special emphasis given to the prospects of sterile neutrino studies.
- Host: Kim Palladino
- Astronomy Colloquium
- Towards understanding the inefficiency of star formation in galaxies
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Coffee and Cookies 3:30 pm, Talk begins 3:45 pm
- Speaker: Andrey Kravtsov, The University of Chicago
- Abstract: One of the long-standing puzzles of galaxy formation is the global inefficiency with which galaxies convert baryonic matter available to them into stars. This inefficiency is manifested in 1) the fact that ratio of baryon mass observed within galaxies to the total inferred mass of their host halos is much smaller than the universal baryon fraction and 2) the fact that galaxies convert their observed gas into stars on ~2-10 Gyr time scale (gas depletion time), which is much longer than any dynamical time scale within galaxies.
I will review recent progress in galaxy formation simulations due to improvements in treatment of stellar feedback and star formation, which sheds light into the 1st aspect of inefficiency. I will present a new model, in which local star formation efficiency is modelled "on the fly" using a turbulence-based subgrid model based on results of high-resolution simulations of molecular clouds. The model predicts a wide variation of star formation efficiency per free fall time at odds with the usual assumption of constant efficiency. At the same time, our model predicts distribution of star formation rates in broad agreement with observations of both local and resolved extragalactic GMCs. I will show that with realistic implementation of stellar feedback this modelling can reproduce the basic properties of star formation and the Kennicutt-Schmidt relation in galaxies, such as the Milky Way. Finally, using insights from such simulations I will present a simple model explaining why star formation in galaxies is inefficient and depletion times are long. - Host: Astronomy Department and Physics
Friday, March 31st, 2017
- Physics Department Colloquium
- The Dark Matter in the Universe
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall
- Speaker: Katherine Freese, University of Michigan
- Abstract: "What is the Universe made of?” This question is the longest outstanding problem in all of modern physics, and it is one of the most important research topics in cosmology and particle physics today. The bulk of the mass in the Universe consists of a new kind of dark matter particle, and the hunt for its discovery in on. I'll start by discussing the evidence for the existence of dark matter in galaxies, and then show how it fits into a big picture of the Universe containing 5% atoms, 25% dark matter, and 70% dark energy. Leading candidates for the dark matter are Weakly Interacting Massive Particles (WIMPs), a generic class of particles that are electrically neutral and do not participate in strong interactions, yet have weak-scale interactions with ordinary matter. There are three approaches to experimental searches for WIMPS: at the Large Hadron Collider at CERN in Geneva; in underground laboratory experiments; and with astrophysical searches for dark matter annihilation products such as with the IceCube detector at the South Pole. Currently there are claimed detections in multiple experiments --- but they cannot possibly all be right. The results are puzzling and the hints of detection will be tested soon. At the end of the talk I'll turn to dark energy and its effect on the fate of the Universe.
- Host: Susan Coppersmith