Talks & Events
KICP Colloquia: 2003
Millimeter Observations of the Early Universe from the High Atacama Plateau and the Not-So-High West Virginia Appalachians
Mark Devlin, University of Pennsylvania
I will discuss the proposed Atacama Cosmology Telescope (ACT). ACT is a low background 6 meter diameter telescope designed to study the early universe with three large arrays of millimeter-wave detectors. I will also discuss the Penn Array Receiver (PAR). The PAR consists of a small 64 element array of TES detectors operating at 90 GHZ. It will be mounted on the 100 meter diameter Green Bank Telescope in West Virginia. Finally, I will give a brief status report on the Balloon-born Large Aperture Submillimeter Telescope (BLAST).
What General Relativity really means
Sean Carroll, University of Chicago/CfCP
According to the cliche, you never understand a subject until you teach it. Not true it turns out to be necessary to write a textbook. I will give a pedagogical talk on aspects of GR which have become clear to me while writing such a book, focusing on: 1) the physical content of Einstein's equation, and 2) how GR could reasonably have been different, and consequently what alternatives are most worth of our attention. No prior knowledge of GR is assumed in fact it's discouraged.
A Boltzmann Approach to Modern Cosmology
Chung-Pei Ma, University of California, Berkeley
I will describe a few examples of how the Boltzmann equation can help us understand the evolution of cosmic structures in the universe. One application is the gravitational clustering of massive neutrinos and the implications for the nature of ultra high energy cosmic rays. I will also discuss the surprising finding that cold dark matter collapses into a cuspy universal form and how a kinetic Boltzmann approach may shed light on the origin of this behavior.
Is CP Violation universal, and what does it mean for the Universe?
LISA and the New Astronomy
Neil J. Cornish, U Montana
The Laser Interferometer Space Antenna (LISA) is one of the two Great Observatories to be built for NASA's Beyond Einstein program. Unlike the earlier Great Observatories, Hubble, Chandra, and Compton, LISA will be the first to explore the Universe from outside the electromagnetic spectrum. LISA will detect low frequency gravitational waves from a variety of sources, but LISA's primary mission is no more the detection of gravitons than Hubble's is the detection of photons. Rather, LISA will be a powerful astronomical observatory that will allow us to study how black holes form and how they evolve,perform a census of close binary systems in our galaxy and beyond, map the spacetime of a black hole, and place limits on the gravitational waves produced by the Bing Bang. The presentation will describe the LISA mission and explain how LISA can be used to do astronomy.
Frontiers in Neutrino Astrophysics
John Beacom, Fermilab
There has been great progress in neutrino physics recently, with the solar and atmospheric neutrino problems finally solved. Now what? I will argue that this is not the beginning of the end in neutrino physics, but only the end of the beginning. Knowledge of the neutrino mixing parameters makes neutrinos a unique and reliable probe of astrophysical objects and cosmology. It also allows much more sensitive tests of exotic neutrino properties that would indicate truly new physics. I will discuss the present picture of neutrino physics and some of the key steps to complete it, and then the promising future for opening new windows on the universe and the mysterious neutrino sector.
Might Lorentz symmetry be violated?
Ted Jacobson, University of Maryland
Quantum gravity considerations suggest that Lorentz symmetry may hold only approximately. This talk will discuss a phenomenological framework for incorporating Lorentz violation into particle physics and general relativity, some of the possible consequences, and the observational constraints. High energy astrophysics observations impose such strong constraints as to render Lorentz violation at order E/E_Planck highly unlikely.
Neutrino Mixing, Oscillations and Neutrinoless Double-Decay:Majorna and Cuore Next Generation Experiments
Frank Avignone, USC
Analyses of the latest solar neutrino oscillation data from both Super-Kamiokande and from SNO have significantly changed the structure of the neutrino-mising matrix. The very recent reported results from the KAMLAND experiment strongly support the Large Mixing Angle (LMA) solution to the solar neutrino problem. The new values of the mixing angles differ significantly from those that favored the bi-maximal mixing scenario. The new experimental values strongly suggest that the probability that planned next generation double-beta decay experiments have a significant probability of being able to discover this exotic decay mode and measure the effective Majorana mass of the electron-neutrino. This is the only pratical method of determining that neutrinos are Majorana particles. The measurement of the effective mass would determine the mass scale of the three families of neutrinos in the three family scenario. The phenomenology of neutrino-mixing, neutrino oscillations, and the connection to the neutrinoless double beta decay will be reviewed. A propsed next generation experiments, MAJORANA, and CUORE will be described in some detail and their projected sensitivities and discovery potential be discussed. Neutrino oscillation experiments have clearly demonstrated that neutrinos have mass and they have established the minimum mass of the heaviest neutrino, but even in principle they can not determine the mass scale but only the differences between the squares of the neutrino mass-eigenvalues. Neutrinoless double beta decay is the next important step in gaining a more complete understanding of neutrino physi. Their time has come. The status of the MAJORANA proposal and the CUORICINO experiment will also be discussed.
Supermassive Black Holes in Galactic nuclei
Monica Valluri, University of Chicago
There is now irrefutable dynamical evidence for Supermassive Balckholes at the centers of several nearby galaxies and complelling evidence that compact mass concentrations-probably black holes exist in the nuclei of an handful of galaxiees with elliptical/bulge components. One of the most important developments in the study of the demographics of galactic nuclei was the simultaneous discovery (by two different groups) of a tight empirical correlation between the masses of SBHs and the velocities of stars in their host bulges. There has been considerable controversy regarding the precise parameters of this correlation, and this has spawned a plethora of theoretical models for the formation of supermassive black holes. Many of the SBHs contributing to this correlation have had their masses estimated from three-integral, axisymmetric, orbit-based modeling algorthms which aim to recover the parameters defining the gravitational potential in spheroidal stellar systems using stellar kinematical data from the Hubble Space Telescope's STIS Spectograph and other spectographs. I will review the demographic realtionships between supermassive black holes and their host galaxies and critically evaluate the ability of the most popular modelling algorithms to recover the masses of central blackholes. I will show that the black hole mass estimation problem is generically under-determined: a range of parameters can provide equally good fits to the data, making it impossible to assign best-fit values. I will show that the range of degeneracy in black hole mass depends strongly on the degree to which the data resolve the radius of influence of the black hole, implying that the modelling errors on existing black hole mass estimates have so far been significantly underestimated.
The mass composition of cosmic rays above 10^17eV
Alan Watson, Leeds
It is becoming clear that we will have excelent new data on the energy spectrum and mass composition of cosmic rays up to 10^20 eV within the next few years. However, it may be diffcult to make firm statements about the origin of the cosmic rays from these data alone and we also need new information on the mass composition above 10^17 eV. I will review the present situation, showing that, while there is currently much confusion, there is also some hope for the future.
Peculiar Velocities, Gas Temperatures and other Benefits of Multi-frequency Sunyaev-Zeldovich Observations of Galxy Clusters
Lloyd Knox, University of California, Davis
We will soon have SZ surveys conducted from four continents and from space as well. I will review the motivation for these surveys and then concentrate on the benefits of flux measurements at multiple frequencies. Such measurements of galaxy clusters in the 30 to 350 GHz range can be used to simultaneously determine a galaxy cluster's integrated pressure along the line of sight, its bulk velocity with respect to the cosmic microwave background (CMB), and its mass-weighted average gas temperature. I will show how the Sunyaev-Zeldovich effects make these determinations possible in principle and how contamination from the CMB itself, from high-redshift dusty galaxies and from synchrotron-emitting cluster galaxies can be controlled, making it possible in practice. I will highlight the benefits of multi--frequency measurements to a broad range of cosmological applications.
Physics to Do with Cosmic Neutrinos
Tom Weiler, Vanderbilt University
We begin with a brief overview of extreme-energy (EE) cosmic ray data, arguments for EE cosmic neutrinos, and the experiments which will perform neutrino astronomy. Next we discuss particle physics aspects of neutrinos which can best(or only) be probed using the large energy E or large distance L or cosmic sources. Potentially measurable neutrino physics includes the detection of the relic neutrino density liberated one second after the big-bang, finite neutrino lifetimes, and neutrino doubling ("pseudo-Dirac" neutrinos). The neutrino-nucleon cross-section at a CMS energy orders of magnitude beyond terrestrial accelerators is also accessible.Measurement of an anomalously large neutrino cross-section would indicate radically new physics(e.g. low string-scale, extra dimensions, precocious unification),while a smaller than expected cross-section would reveal an aspect of QCD evolution.
Quasar Microlensing -- Results From <10 milliMACHOS
Chris Kochanek, Ohio State
Quasar microlensing is the forgotten stepchild of microlensing experiments primarily because it seemed too difficult to convert the observational data into physical results. We have developed an analysis method that can be applied to quasar microlensing data of arbitrary complexity and apply it to the OGLE data for the four-image quasar lens Q2237+0305. The results are surprisingly good given that the data set is equivalent to 2 weeks of observations by a large Galactic microlensing project. We estimate the stellar mass fraction, the average stellar mass, the size of the quasar accretion disk and the mass of the quasar black hole.
The Red-Sequence Cluster Surveys
Mike Gladders, Carnegie Observatory
The Red-Sequence Cluster Survey is an ~100 square degree imaging survey in the R and z' filters designed to locate and characterise galaxy clusters to redshifts as high as 1.4. After a brief discussion of the survey motivation, execution and basic results, this talk will focus on recent science results arising from the RCS cluster catalogs. Topics will include strong lensing by clusters and the properties of a sub-sample of RCS clusters at z>1. Time permitting, I will also discuss recent work aimed at quantifying the evolution of the radio source population in clusters over the entire RCS redshift range, and the global correlations between large scale structure as traced by both AGN and clusters.