Events at Physics
Events on Thursday, January 30th, 2014
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Understanding Nature's Particle Accelerators Using Multi-wavelength Signatures
- Time: 2:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Udara Abeysekara, Michigan State
- Abstract: Nature's particle accelerators, such as Pulsars, Pulsar Wind Nebulae, Active Galactic Nuclei and Supernova Remnants accelerate charged particles to very high energies that then produce high energy photons. The particle acceleration mechanisms and the high energy photon emission mechanisms are poorly understood phenomena. These mechanisms can be understood either by studying individual sources in detail or, alternatively, using the collective properties of a sample of sources. Recent development of GeV survey instruments, such as Fermi-LAT, and TeV survey instruments, such as Milagro and HAWC, provides a large sample of high energy gamma-ray flux measurements from galactic and extra-galactic sources. In this talk, I will present a new multi-wavelength technique, developed to study the collective properties of a given GeV pulsar sample, using the GeV-TeV correlation between pulsars and their associated pulsar wind nebulae. This method is able to measure the beaming factor vs. pulsar spin-down luminosity distribution of a Fermi-LAT GeV pulsar sample. Interestingly, it appears that pulsar acceleration model simulations may be distinguishable by their beaming factor predictions. I will also compare the simulated beaming factor vs. pulsar spin-down luminosity distributions with the experimental results and present the future phase of this technique.
- Host: Vandenbroucke
- Astronomy Colloquium
- "Baryonic physics in galaxy evolution as seen by the CALIFA survey"
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Jakob Walcher, Astrophysical Institute Potsdam
- Abstract: Ironically, while the predictions on the dark side of the cosmological "concordance" model LambdaCDM are well understood theoretically, many open questions in cosmology and galaxy evolution revolve around the difficult physics of the luminous, baryonic matter. The Calar Alto Legacy Integral Field Area Survey (CALIFA) is designed to study the baryonic physics of nearby galaxies by providing integral field spectroscopic data cubes in the optical wavelength domain of 600 galaxies of all morphological types. I will present the survey, show the current status, describe the science potential and advertise recent science results. Science results to be shown address a number of topics, among them 1) the powering mechanism of so-called LINER galaxies, 2) the origin of the mas-metallicity relationship, 3) baryonic vs. total matter content, 4) mass build-up of stars over the history of the univers