KICP Seminars & Colloquia, Winter 2006

Seminar schedule for Winter 2006
January 4, 2006
Wednesday colloquium
Felix Aharonian
MPI Heidelberg
Astrophysics and Cosmology with HESS   [Abstract]
January 11, 2006
Wednesday colloquium
David Tytler
UCSD
The tension in Standard Big Bang Nucleosynthesis:the baryon density, D, He and Li.   [Abstract]
January 13, 2006
Friday noon seminar
Kathryn Miknaitis
University of Chicago
SNO and Solar Neutrinos: Beyond the Solar Neutrino Problem   [Abstract]
January 18, 2006
Wednesday colloquium
Vasileios Paschalidis
University of Chicago
Well-posedness of the Cauchy problem of General Relativity   [Abstract]
January 20, 2006
Friday noon seminar
Mark G. Jackson
Fermilab
Detecting Cosmic Superstrings   [Abstract]
January 25, 2006
Wednesday colloquium
Timothy Beers
Michigan State University
Carbon Enhancement in the Galaxy -- A New Probe of the First Stars   [Abstract]
January 27, 2006
Friday noon seminar
Jonathan Feng
University of California, Irvine
Identifying Dark Matter   [Abstract]
February 1, 2006
Wednesday colloquium
Jeff Peterson
CMU
Searching for Enlightenment   [Abstract]
February 3, 2006
Friday noon seminar
Alexia Schulz
University of California , Berkeley
Baryon Accoustic Oscillations   [Abstract]
February 8, 2006
Wednesday colloquium
Christine Jones
Harvard-Smithsonian Center for Astrophysics
Reflections of AGN Outbursts In the Hot Gas in Galaxies and Clusters   [Abstract]
February 10, 2006
Friday noon seminar
Carlos Wagner
Argonne National Laboratory and University of Chicago
Dark Matter and New Physics Searches at hadron and lepton colliders   [Abstract]
February 14, 2006
Astronomy Special Seminar
Todd Thompson
Princeton University
Radiation Pressure Supported Starburst Disks and the Fueling of Active Galactic Nuclei   [Abstract]
February 15, 2006
Wednesday colloquium
Joseph Fowler
Princeton University
Probing fundamental physics with the Atacama Cosmology Telescope   [Abstract]
February 17, 2006
Friday noon seminar
Peder Norberg
University of Edinburgh
On the luminosity dependence of quasar clustering   [Abstract]
February 21, 2006
Astronomy Special Seminar
Masao Sako
KIPAC/Stanford
The Search for Cosmic Supernova Explosions with SDSS-II   [Abstract]
February 22, 2006
Wednesday colloquium
Roland Diehl
Max-Planck-Institute for Extraterrestrial Physics
High-Energy Astrophysics with Gamma-Ray Telescopes   [Abstract]
February 24, 2006
Friday noon seminar
Jose Blanco-Pillado
New York University
Racetrack Inflation   [Abstract]
February 28, 2006
Astronomy Special Seminar
Sebastian Heinz
Massachusetts Institute of Technology
Harassing the Neighbors: The Impact of Relativistic Jets on the Universe at Large   [Abstract]
March 1, 2006
Wednesday colloquium
Andrew Blain
CalTech
Probing high-redshift luminous galaxies into the ALMA epoch   [Abstract]
March 2, 2006
Astronomy Colloquium
Maxim Lyutikov
University of British Columbia
Radiation transfer in neutron star magnetospheres: the binary pulsar and magnetars   [Abstract]
March 3, 2006
Friday noon seminar
Gary Hill
University of Wisconsin, Madison
Neutrino astronomy with IceCube and AMANDA   [Abstract]
March 8, 2006
Wednesday colloquium
John Martin Laming
Naval Research Laboratory
How Did Cassiopeia A Explode? A Chandra Very Large Project   [Abstract]
March 10, 2006
Friday noon seminar
Tom Crawford
University of Chicago
Constraining Cosmology with the South Pole Telescope   [Abstract]
March 17, 2006
Friday noon seminar
Nemanja Kaloper
University of California, Davis
How I Learned to Like w<-1 Dark Energy   [Abstract]
 
WEDNESDAY COLLOQUIA

  • January 4, 2006 | 3:30 PM | RI 480
    Astrophysics and Cosmology with HESS
    Felix Aharonian, MPI Heidelberg

    The High Energy Stereoscopic System (HESS) of imaging atmospheric Cherenkov telescopes is a powerful multi-functional tool for spectrometric, morphological and temporal studies of nonthermal phenomena and objects representing different Galactic and Extragalactic source populations. I will overview the recent discoveries by HESS with an emphasis on the detection of TeV emission from relatively distant blazars, and discuss some cosmological implications of these results for the Extragalactic Background Light (EBL) at optical and near-infrared wavelengths.
  • January 11, 2006 | 3:30 PM | RI 480
    The tension in Standard Big Bang Nucleosynthesis:the baryon density, D, He and Li.
    David Tytler, UCSD

    Three methods of measuring the cosmological baryons density now agree within about 10%: the CMB, the D/H ratio using Standard Big Bang Nucleosynthesis, and the Lyman-alpha absorption from the IGM at z=2 to 3. We recently measured the mean amount of absorption in the IGM with an error of 1%, and we use these measurements, and a large set of hydrodynamic simulations to determine the cosmological and astrophysical parameters of the IGM, including the temperature and the baryon density. Using this baryon density, SBBN predicts a factor 3 more 7Li than is seen in halo stars, and systematically more 4He that most measurements. We review the systematic errors and new measurements, and we discuss modifications to BBN that might explain the tension between D, He and Li.
  • January 18, 2006 | 3:30 PM | RI 480
    Well-posedness of the Cauchy problem of General Relativity
    Vasileios Paschalidis, University of Chicago

    The most common approach to solving the Cauchy problem of General Relativity (GR) is by implementing free evolution schemes of the 3+1 decomposition of Einstein's equations. A long-standing problem in numerical relativity is achieving long-term and stable numerical integration of the GR equations. At present, this is possible for rather short times or for special symmetric cases. In this talk, we will present a general theory for the study of well-posedness of constrained evolution of 3+1 formulations of GR. This new approach incorporates the constraint equations directly and therefore is principally different from standard analyses of well-posedness of free evolution schemes. We will demonstrate that well-posedness of constrained evolution of 3+1 formulations of GR depends entirely on the properties of the gauge and comment on consequences of this result.
  • January 25, 2006 | 3:30 PM | RI 480
    Carbon Enhancement in the Galaxy -- A New Probe of the First Stars
    Timothy Beers, Michigan State University

    Recent large surveys of metal-poor stars in the Galaxy have revealed that a surprising fraction of them are enhanced in their carbon-to-iron ratios by factors of from 10-10,000 relative to the solar ratio. Although most of the stars in the metallicity interval -2.7 < [Fe/H] < -2.0 are likely to have arisen from Asymptotic Giant Branch processing (and subsequent dumping via mass transfer to a surviving companion), there exist many stars with [Fe/H[ < -3.0 (including the two lowest [Fe/H] stars known, with [Fe/H] < -5.0) that cannot be accounted for by this process. Rather, primordial (or nearly primordial) progenitors are implicated. I report on the existing information from present surveys, and describe the results that will come from the recently-funded extension of the SDSS, which includes the program SEGUE = Sloan Extension for Galactic Understanding and Exploration. SEGUE will identify some 20,000 stars with [Fe/H] < -2.0, several thousand of which are expected to be carbon enhanced.
  • February 1, 2006 | 3:30 PM | RI 480
    Searching for Enlightenment
    Jeff Peterson, CMU

    In a remote valley in western China stand 10,000 television antennas spread across ten square kilometers. Tied together by an array of hundreds of PC computers this system, the Primeval Structure Telescope (PaST), will soon be used to search for evidence of the early ionization of the Universe. Today most hydrogen gas in the cosmos is ionized. But, before the first stars formed, neutral hydrogen was ubiquitous. By imaging 21 cm hydrogen hyperfine emission from this gas at redshifts from 6 to 25 the ionization state of the early universe can be explored. As the first stars began to light up, the 21 cm emission was extinguished, leaving a patchy radio sky. This patchy structure will be imaged with the PaST array, allowing the era of the first stars to be dated and studied.
  • February 8, 2006 | 3:30 PM | RI 480
    Reflections of AGN Outbursts In the Hot Gas in Galaxies and Clusters
    Christine Jones, Harvard-Smithsonian Center for Astrophysics

    Chandra X-ray images show the presense of shocks, jets, cavities and buoyant bubbles in the hot gas in galaxies, groups and clusters. These features all owe their origin to outbursts from the supermassive black hole (SMBH) at the nucleus of the system. In this talk I will review recent results on AGN outbursts in the rich clusters MS0735.6+7421, Perseus, Hercules A, Hydra A and Virgo as well as the effects of outbursts and the X-ray luminosities of low luminosity AGN in a sample of 160 early-type galaxies.
  • February 15, 2006 | 3:30 PM | RI 480
    Probing fundamental physics with the Atacama Cosmology Telescope
    Joseph Fowler, Princeton University

    The Atacama Cosmology Telescope (ACT) is a millimeter-wave telescope designed to map the CMB temperature at arcminute angular scales. ACT will image a few hundred square degrees of the CMB in the southern sky from a site in the Atacama desert. In addition to measuring the primary CMB power spectrum, ACT will survey for massive galaxy clusters through their Sunyaev-Zel'dovich (SZ) signal. Three frequency bands around the SZ null--145, 215, and 265 GHz--will help to separate cluster signals from primordial anisotropy and from point sources. The maps will offer data on a wide variety of questions in fundamental physics and cosmology, including the growth of structure, and the spectrum of primordial perturbations.
  • February 22, 2006 | 3:30 PM | RI 480
    High-Energy Astrophysics with Gamma-Ray Telescopes
    Roland Diehl, Max-Planck-Institute for Extraterrestrial Physics

    Gamma-rays are messengers of high-energy processes throughout the Universe: Nuclear reactions create radioactive isotopes, and particles which have been accelerated into the relativistic regime create non-thermal radiation. The penetrating nature of these gamma-rays implies that even sources which are invisible or optically thick in other wavelengths can be studied through their gamma-ray emission. The Compton Observatory had surveyed the gamma-ray sky, and had found a few surprises, beyond the images that have been obtained from cosmic-ray interactions with interstellar gas and from diffuse radioactivities originating from cosmic nucleosynthesis. ESA's INTEGRAL observatory recently made possible to probe the low-energy gamma-ray regime at better sensitivity, and, most importantly, add spectroscopy power to resolve characteristics gamma-ray lines. We will discuss the interpretations and findings from recent observations at high energies and the corresponding source models, specifically addressing sources of nucleosynthesis and of particle acceleration in our Galaxy.
  • March 1, 2006 | 3:30 PM | RI 480
    Probing high-redshift luminous galaxies into the ALMA epoch
    Andrew Blain, CalTech

    I will discuss the observational progress made in understanding the nature and evolution of luminous far-IR galaxies, and highlight the most promising future investigations that lead towards exquisite imaging quality of their optically thick emission from ALMA in about 2012.
  • March 8, 2006 | 3:30 PM | RI 480
    How Did Cassiopeia A Explode? A Chandra Very Large Project
    John Martin Laming, Naval Research Laboratory

    In April/May 2004 the Chandra X-ray Observatory observed the Cassiopeia A supernova remnant for 1 million seconds as one of the first of the newly instituted 'Very Large Projects'. This is the deepest ever x-ray observation of a supernova remnant, and allows observers to exploit the angular resolution of the Chandra mirrors to the fullest extent, in that spectra of adequate signal/noise can be extracted from very small spatial regions in most locations within the remnant. I will describe progress to date, and future plans, for the analysis of this unique dataset, paying specific attention to quantifying the nature and degree of asymmetry in the explosion, and the abundances and locations of chemical elements synthesized therein.

 
FRIDAY NOON SEMINARS

  • January 13, 2006 | 12:00 PM | LASR Conference Room
    SNO and Solar Neutrinos: Beyond the Solar Neutrino Problem
    Kathryn Miknaitis, University of Chicago

    In 2001 (and more definitively in 2002), the Sudbury Neutrino Observatory (SNO) experiment demonstrated that electron neutrinos produced in the solar interior were changing flavor prior to reaching the earth. SNO's measurements of solar neutrino flavor change conclusively solved the long-standing "Solar Neutrino Problem" and provided evidence for the existence of neutrino mass. Far from being the end of the story, these and other recent neutrino physics results have opened up a rich field of fundamental questions to be probed by current and future experiments. I will give an overview of several of the major open questions in neutrino physics and discuss how SNO's recent and ongoing measurements fit into the bigger project of unraveling the neutrino's mysteries.
  • January 20, 2006 | 12:00 PM | LASR Conference Room
    Detecting Cosmic Superstrings
    Mark G. Jackson, Fermilab

    I will discuss the recent developments suggesting that cosmic superstrings are theoretically possible, and observationally distinct from conventional cosmic strings. First reviewing the appearance of cosmic strings in string theory and some models of inflation therein, I show how their formation can still be consistent with existing CMB/pulsar bounds. I then profile methods by which cosmic strings can be detected. Finally I will explain how to differentiate cosmic superstrings from conventional vortex cosmic strings, and how this can be used to extract information about string parameters and extra dimensions.
  • January 27, 2006 | 12:00 PM | LASR Conference Room
    Identifying Dark Matter
    Jonathan Feng, University of California, Irvine

    Recent breakthroughs in cosmology indicate that a quarter of the Universe is composed of dark matter, but the microscopic identity of dark matter remains a deep mystery. I will review recent progress in resolving this puzzle, focusing on two well- motivated classes of dark matter candidates: WIMPs and superWIMPs. In each of these classes, stable particles are naturally produced in the early Universe with the right relic density to contribute to dark matter, and dark matter particles have mass around 100 GeV, the energy scale soon to be probed in detail at particle colliders. I will discuss the theoretical motivations for these possibilities, their diverse implications at the interface of particle physics, astroparticle physics, and cosmology, and the prospects for identifying dark matter in the coming years.
  • February 3, 2006 | 12:00 PM | LASR Conference Room
    Baryon Accoustic Oscillations
    Alexia Schulz, University of California , Berkeley

    Baryon oscillations in the matter power spectrum, used as a standard ruler, have the potential to strongly constrain the expansion history of the universe and the nature of the dark energy. Localizing the features in the galaxy power spectrum and relating them to features predicted in the dark matter spectrum necessitates a theoretical understanding of such complex issues as galaxy bias, non-linear evolution, and redshift space distortions. Using the halo model to analytically investigate these effects, we have identified trends that relate the scale dependance of the galaxy bias to the halo occupation distribution (HOD). These trends reveal a natural parametrization of the galaxy power spectrum. Combining this parametrization with the results of N-body simulations, we have quantified the impact of the HOD parameters on the scale dependance of the galaxy bias. We show that the bias in real space is less profoundly affected by shifts in the HOD parameters, which suggests that baryon oscillation measurments in the correlation function may prove to be more robust to the theoretical uncertainties that are baryon oscillation measurments in the galaxy power spectrum.
  • February 10, 2006 | 12:00 PM | LASR Conference Room
    Dark Matter and New Physics Searches at hadron and lepton colliders
    Carlos Wagner, Argonne National Laboratory and University of Chicago

    Dark Matter candidates abound in models of new physics. The best motivated candidates are associated with extensions of the Standard Model (SM) that provide a natural mechanism for electroweak symmetry breaking. Production of a weakly interacting, neutral, dark matter candidate at hadron and lepton colliders will lead to events with missing energy. In this talk I will discuss the prospects of detecting such dark matter candidates at the Tevatron, the LHC and the ILC.
  • February 17, 2006 | 12:00 PM | LASR Conference Room
    On the luminosity dependence of quasar clustering
    Peder Norberg, University of Edinburgh

    We present detailed clustering measurements for a flux limited sample of ~14,000 quasars extracted from the 2dF QSO Redshift Survey(2QZ) in the redshift range 0.810^12 M_sun and that the mean mass of their host haloes is of the order of 10^13 M_sun. We then split each redshift interval into several luminosity intervals, for which we estimate the quasar projected auto and cross-correlation functions. Fitting the data with a biased CDM model and using several statistical tests, we find that models with luminosity dependent clustering tend to be statistically favoured. However, the quality of the data is not good enough to accurately quantify how quasar biasing depends on luminosity. We critically discuss the limitations of our dataset, as well as the method, and show that a much larger sample is needed to rule out current models for luminosity segregation.
  • February 24, 2006 | 12:00 PM | LASR Conference Room
    Racetrack Inflation
    Jose Blanco-Pillado, New York University

    Four dimensional effective actions of many of the currently studied extra-dimensional theories seem to contain massless scalar fields called moduli. Giving these fields a potential is crucial to make these theories compatible with observations. It is therefore natural to explore the possibility that before they settle down to the true minimum of their potentials these fields could be relevant for cosmology, in particular they could be the source of an inflationary expansion period of the universe. In this talk, I will review ealier attempts to follow these ideas and present a new model of topological modular inflation in the context of the recently develop flux compactifications within string theory.
  • March 3, 2006 | 12:00 PM | RI 480
    Neutrino astronomy with IceCube and AMANDA
    Gary Hill, University of Wisconsin, Madison

    Since the early 1990's, the South Pole station in Antarctica has been the site of the development and operation of the world's first ice-Cherenkov neutrino telescopes, AMANDA and IceCube. The AMANDA telescope was completed in 2000 and has been used to search for the first high-energy neutrinos from beyond the earth. The successor to AMANDA, IceCube, will be a kilometre-scale neutrino and air shower detector with unprecedented sensitivity to astrophysical sources of neutrinos. In this talk, a summary of the results from AMANDA and report on the first two construction seasons of the IceCube telescope will be given. The prospects for extraterrestrial neutrino observation with the full IceCube array, slated for completion in 2010, will be discussed.
  • March 10, 2006 | 12:00 PM | LASR Conference Room
    Constraining Cosmology with the South Pole Telescope
    Tom Crawford, University of Chicago

    A new millimeter/submillimeter-wave telescope is being constructed for deployment at the NSF South Pole research station. This telescope, with a 10-meter clear aperture, is designed for conducting large area surveys with unprecedented sensitivity to low surface brightness emission such as primary and secondary CMB anisotropy. The first camera for the new South Pole Telescope (SPT) will be a 1000-element bolometer array designed to conduct a blind survey over a few thousand square degrees, searching for galaxy clusters through their Sunyaev-Zel'dovich Effect. The survey should find many thousands of clusters with a selection criterion that is remarkably uniform with redshift. Armed with redshifts obtained from optical/IR follow-up, the survey yields should allow tight constraints to be placed on the equation of state of the dark energy. The cluster survey data will also be used to measure the small-scale primary and secondary CMB power spectra well beyond current limits of sensitivity and resolution, improving our knowledge of the spectrum of primordial fluctuations, the mass of the neutrino, and other cosmological measurables. Finally, a planned polarimeter for the SPT will have the statistical power to constrain the energy scale of inflation through measurement of the B-mode power spectrum of the polarized CMB.
  • March 17, 2006 | 12:00 PM | LASR Conference Room
    How I Learned to Like w<-1 Dark Energy
    Nemanja Kaloper, University of California, Davis

    We will discuss mechanisms which can simulate dark energy with w<-1, but do not use any ghosts, phantoms or other occult beasts.

 
ASTRONOMY COLLOQUIA

  • March 2, 2006 | 1:30 PM | AAC 123
    Radiation transfer in neutron star magnetospheres: the binary pulsar and magnetars
    Maxim Lyutikov, University of British Columbia

    This talk will be separated into two parts. First, I will discuss eclipses in the binary pulsar system PSR J0737-3039, where the faster pulsar A is eclipsed once per orbit. A simple model of eclipses based on synchrotron absorption on closed field lines of slower pulsar B reproduces the complicated observed light curve down to intricate details and provides a direct proof of the long-standing assumption of dipolar magnetic fields of neutron stars. In a second part I will describe a model of non-thermal emission from magetars due to resonant cyclotron scattering of surface radiation in their magnetospheres. Applying the model to anomalous X-ray pulsar 1E 1048.1—5937 gives a fit just as good as less physically motivated “black body plus powerlaw” spectra and allows one to determine density and temperature of the magnetospheric plasma.

 
ASTRONOMY SPECIAL SEMINARS

  • February 14, 2006 | 12:00 PM | RI 480
    Radiation Pressure Supported Starburst Disks and the Fueling of Active Galactic Nuclei
    Todd Thompson, Princeton University

    The UV radiation produced by massive stars in the dense ISM of starburst galaxies is absorbed, scattered, and reprocessed into the infrared by dust grains. The radiation pressure associated with the diffusion of these photons out of the starburst disk can provide the dominant vertical support against gravity. This conclusion is particularly robust when the disk is optically thick to its own infrared radiation, as in the central regions of Ultra-luminous Infrared Galaxies (ULIRGs). I will discuss the implications of this important feedback process. In particular, because the disk radiates at its Eddington limit (for dust), the "Schmidt-law" for star formation changes qualitatively. I compare the model with observations of local and high-redshift ULRIGs. I extend the model from many-hundred parsec scales to sub-parsec scales and address the problem of AGN fueling. A strong bifurcation exists between models whose spectra are starburst dominated and those that are AGN dominated. Models that fuel AGN contain a compact starburst on parsec scales. A natural consequence of this starburst component is the generation of a radiation pressure supported photosphere with vertical extent of order the disk radius. This structure may be the "obscuring torus" required in unified models of AGN. I further speculate on the origin of the disk(s) of young stars at the Galactic Center. Lastly, I show that radiation pressure may be important in driving galactic winds and in setting the "M-sigma" relation between the velocity dispersion of spheroids and the masses of the black holes they harbor.
  • February 21, 2006 | 12:00 PM | LASR
    The Search for Cosmic Supernova Explosions with SDSS-II
    Masao Sako, KIPAC/Stanford

    The Sloan Digital Sky Survey II has started a massive supernova search, where 300 square degrees of the sky are scheduled for multi-band imaging on a cadence of two days during the fall seasons of 2005 - 2008. A unique large-format imaging camera array with a total of 120 million pixels is capable of recording 200 GB of data in a single night of observing, allowing efficient discoveries of supernova explosions out to z = 0.4, or about 1/3 of the way back to the Big Bang. The first-year campaign, which ended in December 2005, was a remarkable success and a total of 126 SN Ia in the redshift interval of 0.01 < z < 0.42 were spectroscopically confirmed in the 3-month period. Although our primary focus this year has been SN Ia cosmology, the survey has produced an enormous amount of data of other types of transient sources as well. I will present some early results from the first year of the survey and discuss future prospects.
  • February 28, 2006 | 12:00 PM | RI 480
    Harassing the Neighbors: The Impact of Relativistic Jets on the Universe at Large
    Sebastian Heinz, Massachusetts Institute of Technology

    Relativistic jets are powerful collimated flows emanating from the atmospheres of growing black holes. They are the prime mechanism by which black holes can interact with their large-scale environment, coupling black hole growth with the evolution of large-scale cosmic structure. X-ray evidence from galaxy clusters shows that this interaction is both violent and frequent. Computing resources and numerical methods have reached a level of fidelity where this interaction and its consequences for cosmology can be simulated directly. This provides us with a path towards a new, quantitative understanding of the detailed hydrodynamic processes around powerful jets and their impact on the universe.