Neutron stars are the compact cores of collapsed massive stars. They contain as much mass as our Sun but with radii of the size of the capital beltway. Pulsars are rapidly rotating neutron stars with magnetic fields on the order of 10^11 times that of our Sun. There exists a small population of pulsars with magnetic fields three orders of magnitude greater than canonical pulsars -- the aptly named magnetars. These fields are so high that exotic effects due to quantum electrodynamics cannot be neglected when modeling their emission. The enormous magnetic fields of magnetars power bright X-ray pulsations, clusters of bright X-ray bursts, as well as gamma-ray flares that are energetic enough to disturb the Earth's Ionosphere. I will review how our X-ray observations have cemented the magnetar model for a an enigmatic group of pulsars, for which the magnetar interpretation was controversial for several decades. I will also present recent results on a missing-link between canonical pulsars and magnetars.

Physics Bldg., room 401

The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for almost ten years. Among the retrieved quantities are amount and type of wildfire smoke, desert dust, volcanic effluent, urban and industrial pollution particles, and other aerosols. However, the broad scientific challenges of understanding aerosol impacts on climate and health place different, and very exacting demands on our measurement capabilities. And these data sets, though much more advanced in many respects than previous aerosol data records, are imperfect. In this presentation, I will summarize current understanding of MISR and MODIS aerosol product strengths and limitations, discuss how they relate to the bigger aerosol science questions we must address, and give my view of what we will need to do to progress further.

Purdue University, North Carolina State University and the Georgia Institute of Technology are now using the new Matter & Interactions [1] curriculum in their calculus-based introductory physics courses for science and engineering majors. In this presentation I will discuss our reasons for concluding that this curriculum was right for our students, how we manage its use in courses taken by several thousand students each year and what our assessment data reveal about our students’ learning.

In part, the answer to the first of these questions is the way in which the M&I curriculum helps students to structure and to use the physics they learn. It lays a foundation of learning more advanced material by engaging students in physics’ central enterprise of systematically using a small number of fundamental principles to explain or predict a broad range of phenomena by constructing models of realistic physical systems. Such models must often address matter’s atomic structure, which brings accessible 20th century physics into our introductory courses and makes the courses more coherent by unifying topics like mechanics and thermal physics, like electrostatics and DC circuits and others.

Physics Bldg., room 401

Galaxies in the most underdense regions of the universe, the voids, must have different evolutionary histories than those in denser regions, the walls. This is mainly because of the expected huge difference in their rate of interactions, which is believed to affect the nuclear activity, and thus the growth process of galaxies and their central black holes. It is therefore important to determine the degree to which the void galactic nuclear activity compares to its counterpart in denser environments. I will present the results of a comparison of void and wall systems based on a variety of physical properties and near neighbor statistics, together with spatial clustering calculations, which provide empirical evidence that both small and large scale environment influence the interplay between nuclear supermassive black hole accretion and surrounding stellar activity, and thus the optically dominant power source. I will present these ideas in the context of a potential sequence in the lives of galaxies that suggests a transformation from star-forming via supermassive black hole accretion to quiescence, and show support for this scenario with new Chandra X-ray measurements.

Physics Bldg., room 401