KICP Seminars & Colloquia, Winter 2005

Seminar schedule for Winter 2005
January 7, 2005
Friday noon seminar
Brian Odom
Kavli Institute for Cosmological Physics
A search for physics beyond the Standard Model: measurements of the fine structure constant   [Abstract]
January 14, 2005
Friday noon seminar
Tarek Saab
From milliKelvin to MegaKelvin: How superconductivity can help elucidate cosmology   [Abstract]
January 21, 2005
Friday noon seminar
Lifan Wang
LBL
Supernova Studies and Supernova Cosmology   [Abstract]
January 26, 2005
Wednesday colloquium
Alex Szalay
John Hopkins University
Cosmology with Large Datasets
January 28, 2005
Friday noon seminar
Hiranya Peiris
Kavli Institute for Cosmological Physics
Observing Trans-Planckian Signatures in the Cosmic Microwave Background   [Abstract]
February 4, 2005
Friday noon seminar
Hsiao-Wen Chen
MIT
Unmasking Damped Lya Absorbing Galaxies   [Abstract]
February 9, 2005
Wednesday colloquium
George Dvali
New York University
Gravity at largest observable distances
February 10, 2005
Special seminar
Karl Van Bibber
Lawrence Livermore National Laboratory
A Large-Scale Search for Dark-Matter Axions   [Abstract]
February 17, 2005
Thursday lunch discussion
Jacob Bourjaily
University of Michigan
What is the Cosmological Significance of a Discovery of Wimps at Colliders or in Direct Experiments?   [Abstract]
February 18, 2005
Friday noon seminar
Yong-Seon Song
KICP
Looking for an extra dimension with two windows on acceleration and gravitation   [Abstract]
February 23, 2005
Wednesday colloquium
Rachel Somerville
On the Origin of the Red Sequence and Bimodality of Galaxy Properties   [Abstract]
February 25, 2005
Friday noon seminar
Tanmay Vachaspati
Case Western University
Islands in the Lambda-sea   [Abstract]
February 28, 2005
Special seminar
Roger Penrose
Oxford University
The Road to Reality   [Abstract]
March 2, 2005
Astronomy Special Seminar
Mike Gladders
Carnegie Observatories
Understanding High-Redshift Galaxy Clusters as Cosmological Probes: Recent Results and Instrumentation Developments
March 2, 2005
Astronomy Colloquium
Don Backer
University of California, Berkeley
Pulsar Timing Array: Probing the Nanohertz Gravitational Wave Background
March 4, 2005
Friday noon seminar
Artuu Rajantie
Cosmic strings and high energy physics   [Abstract]
March 9, 2005
Wednesday colloquium
Licia Verde
University of Pennsylvania
constraints on the redshift dependence of the dark energy potential   [Abstract]
March 10, 2005
Special seminar
Raul Jimenez
University of Pennsylvania
Watching galaxies assemble: cosmological star formation and mass assembly history form SDSS spectra
March 11, 2005
Friday noon seminar
Bill Jones
Measurements of the Temperature and Polarization anistropies with Boomerang
March 16, 2005
Astronomy Colloquium
Sarah Gallagher
University of California, Los Angeles
New Insights into Quasar Wind Structure
March 18, 2005
Friday noon seminar
Arthur Lue
Case Western University
Braneworlds and Beyond: Differentiating Modified Gravity from Dark Energy   [Abstract]
 
COLLOQUIA

  • January 26, 2005 | 3:30 PM | RI 480 | Wednesday colloquium
    Cosmology with Large Datasets
    Alex Szalay, John Hopkins University
  • February 9, 2005 | 3:30 PM | RI 480 | Wednesday colloquium
    Gravity at largest observable distances
    George Dvali, New York University
  • February 23, 2005 | 3:30 PM | RI 480 | Wednesday colloquium
    On the Origin of the Red Sequence and Bimodality of Galaxy Properties
    Rachel Somerville,

    The color-magnitude relation and the related dichotomy in the morphological, structural, and spectro-photometric properties of galaxies are well-known and fundamental observed properties of galaxies. These relations seem to be largely in place as early as redshift one. However, standard models of galaxy formation set within the Cold Dark Matter paradigm fail to reproduce either the color-magnitude relation or the observed strong bimodality in galaxy properties. I will show that including the feedback from Active Galactic Nuclei in such models may hold the key to understanding these fundamental observations.
  • March 2, 2005 | 3:30 PM | RI 480 | Astronomy Colloquium
    Pulsar Timing Array: Probing the Nanohertz Gravitational Wave Background
    Don Backer, University of California, Berkeley
  • March 9, 2005 | 3:30 PM | RI 480 | Wednesday colloquium
    constraints on the redshift dependence of the dark energy potential
    Licia Verde, University of Pennsylvania

    Cosmology has now a standard model. This model is described by a handful of cosmological parameters, now determined with unprecedented precision, many of them are measured in multiple independent ways. The standard cosmological model is simple, yet puzzling. The big challenge is to shed some light on the dark energy component, which reveals itself only through the acceleration of the universe. Under the assumtion that dark energy is a slowly rolling scalar field, We develop a formalism to characterize the redshift evolution of the dark energy potential. We show that in principle the shape of this potential can be recovered non-parametrically. Since presently available data do not allow a non-parametric reconstruction, we consider a generic parametric description and use observations of passively evolving galaxies derive constraints on the shape of the dark energy potential in the range 0.1
  • March 16, 2005 | 3:30 PM | RI 480 | Astronomy Colloquium
    New Insights into Quasar Wind Structure
    Sarah Gallagher, University of California, Los Angeles

  •  
    FRIDAY NOON SEMINARS

    • January 7, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      A search for physics beyond the Standard Model: measurements of the fine structure constant
      Brian Odom, Kavli Institute for Cosmological Physics

      I will give an overview of recent measurements of the fine structure constant and of its possible time dependence. The significance of these measurements in terms of searches for physics beyond the standard model will be discussed. I will also present preliminary results for the newest and most precise measurement of the fine structure constant, based on the first fully quantum measurement of the electron magnetic moment, performed at Harvard University.
    • January 14, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      From milliKelvin to MegaKelvin: How superconductivity can help elucidate cosmology
      Tarek Saab,

      Recent great steps taken in the fields of cosmology and astrophysics have lead, inevitably, to new and more detailed sets of questions. X-rays hold the clue to some of the answers by providing diagnostics of the hot inter-stellar gases and plasmas where temperatures reach MegaKelvin (or keV). Superconductors enter the picture by making it possible to satisfy the desire for large, high quality data. In the last few years, detectors based on superconducting technology, have reached maturity and are finding applications in various areas of astrophysics ranging from x-ray spectroscopy to Dark Matter detection. In addition, new concepts based on other low temperature phenomena are being developed and targeted at future experiments. This talk will describe how astrophysics’ desire for higher count rates, energy, timing, and position resolution can be satisfied with detectors operating at mK temperatures.
    • January 21, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Supernova Studies and Supernova Cosmology
      Lifan Wang, LBL

      In recent years, Type Ia supernovae (SNIa) have emerged as the most precise cosmological distance indicators. I will discuss recent observational progresses on the studies of the nature of SNIa, based largely on a multi-year effort of spectropolarimetry observations collected at the ESO-VLT. These observations reveal that SNIa ejecta are highly aspherical at the highest velocity, whereas the asphericity decreases at layer with decreasing expansion velocities. There are indications that the asphericity is dominated by chemical inhomogeneities of the size of the photosphere at the time of optical maximum (~11,000 km/sec). There are strong evidences of the existence of detached clumpy layers, likely enriched in calccium, moving at the highest velocities (~22,000 km/sec) in some SN Ia ejecta. These new findings are not expected in popular models of SN Ia explosions. They provide important clues to the physics of SN Ia explosions. For cosmological applications, I will present recent results using the Color-MAGnitude Intercept Calibration (CMAGIC) of SN Ia. I will discuss future projects of SN Ia observations that aim to obtain a significant sample of SNIa with spectropolarimetry data. I will also discuss the prospects of routine discovery of gravitationally lensed SNIa, and the use of them as cosmological probes.
    • January 28, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Observing Trans-Planckian Signatures in the Cosmic Microwave Background
      Hiranya Peiris, Kavli Institute for Cosmological Physics

      I will examine the constraints cosmological observations can place on any trans-Planckian corrections to the primordial spectrum of perturbations underlying the anisotropies in the Cosmic Microwave Background. Using a specific "toy model", I will present a case study for the sort of constraints one could hope to apply on a well-motivated model of trans-Planckian physics from future high-precision CMB data. Our results show that the amplitude of the tensor perturbations is directly correlated with the detectability of any trans-Planckian modulation in the primordial power spectrum. This is likely to be true for any trans-Planckian modulation in the paradigm of slow-roll inflation.
    • February 4, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Unmasking Damped Lya Absorbing Galaxies
      Hsiao-Wen Chen, MIT

      I will present current results from searching for galaxies giving rise to damped DLA absorbers (DLAs) at z<1. Using 14 galaxies that are known to produce DLA features in the spectra of background QSOs, I will show that intermediate-redshift galaxies possess large HI envelope out to 24-30 h^{-1} kpc radius. In addition, the photometric and spectral properties of these galaxies confirm that DLA galaxies are drawn from the typical field population, and not from a separate population of low surface brightness or dwarf galaxies. Comparisons of the ISM abundances of the DLA galaxies and the metallicities of the absorbers at large galactic radii suggest that some DLAs originate in the relatively unevolved outskirts of galactic disks. An abundance profile characterized by a radial gradient of -0.041+/-0.012 dex per kiloparsec (or equivalently a scale length of 10.6 h^{-1} kpc) is found from galactic center to 30 h^{-1} kpc radius based on an ensemble of six galaxy-DLA pairs. Finally adopting this abundance gradient and known N(HI) profiles of nearby galaxies, I will show that the on-average low metal content of the DLA population can arise naturally as a combination of gas cross-section selection and metallicity gradients commonly observed in local disk galaxies.
    • February 18, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Looking for an extra dimension with two windows on acceleration and gravitation
      Yong-Seon Song, KICP

      The cosmic acceleration was discovered in one of the brane-based models as well as dark energy model. Growth factors are different in the two models when one adjusts parameters to get nearly identical H(z). The two models could be distinguished with independent determinations of both geometrical factors and the growth factors. Cosmic shear due to gravitational lensing, can be used to simultaneously determine the distance-redshift relation, D(z), and the rate of growth of density contrasts, g(z). Both of these functions are sensitive probes of the acceleration. Their simultaneous determination allows for a consistency test and provides sensitivity to physics beyond the standard dark energy paradigm.
    • February 25, 2005 | 12:00 PM | RI 480 | Friday noon seminar
      Islands in the Lambda-sea
      Tanmay Vachaspati, Case Western University

      We propose an alternate cosmological model in which our observable universe is an island in a cosmological constant sea. Initially the universe is filled with cosmological constant of the currently observed value but is otherwise empty. In this eternal or semi-eternal de Sitter spacetime, we show that local quantum fluctuations (upheavals) can violate the null energy condition and create islands of matter. The perturbation spectra of quantum fields other than that responsible for the upheaval, are shown to be scale invariant. With further cosmic evolution the island disappears and the local universe returns to its initial cosmological constant dominated state.
    • March 4, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Cosmic strings and high energy physics
      Artuu Rajantie,

      I will discuss the formation of topological defects such as cosmic strings in the early universe. Depending on physics at very high energies, defects may be formed by different mechanisms. I will review these mechanism, and show that they have certain distinct consequences in the properties and distribution of the produced defects. Astronomical observation of cosmic strings would therefore give us direct information about very high energy physics.
    • March 11, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Measurements of the Temperature and Polarization anistropies with Boomerang
      Bill Jones,
    • March 18, 2005 | 12:00 PM | LASR Conference Room | Friday noon seminar
      Braneworlds and Beyond: Differentiating Modified Gravity from Dark Energy
      Arthur Lue, Case Western University

      The nature of the fuel that drives today's cosmic acceleration is an open and tantalizing mystery. I entertain the suggestion that the acceleration is not the manifestation of yet another new ingredient in the cosmic gas tank, but rather our first real lack of understanding of gravitational physics. I discuss first an intriguing braneworld model (Dvali-Gabadadze-Porrati) and extend the discussion to a more general context, addressing questions about modified-gravity cosmologies and dark energy at astrophysically interesting, and even solar sytem, scales, with these distinctions being subject to imminent observational discrimination.

     
    SPECIAL SEMINARS

    • February 10, 2005 | 1:00 PM | LASR Conference Room | Special seminar
      A Large-Scale Search for Dark-Matter Axions
      Karl Van Bibber, Lawrence Livermore National Laboratory

      Recent progress in experimental cosmology has provided a reasonably precise understanding of the overall energy density budget of the Universe. Matter accounts for about a quarter, only a small fractionof which can be baryonic. What constitutes the predominant dark matter is unknown, although particle relics from the Big Bang are implied, a sufficiently light axion being a leading candidate. Halo axions may be detected by their coherent conversion to microwave photons in a high-Q cavity permeated by a strong magnetic field. A collaboration from LLNL, Florida and Berkeley has developed the world's quietest radio receiver for this search and has achieved sensitivity well into the range of axion models. The experiment is now being upgraded with near-quantum-limited SQUID amplifiers, a breakthrough technology which will reduce the noise temperature of the experiment by a factor of 30, thus enabling a truly definitive search.
    • February 28, 2005 | 7:00 PM | The Oriental Institute, 1155 E. 58th Street | Special seminar
      The Road to Reality
      Roger Penrose, Oxford University

      Oxford University Professor Roger Penrose will discuss his new book, “The Road to Reality” In his remarkable, readable, and massive new book, (over 1100 pages) physicist and mathematician Roger Penrose offers readers the most comprehensive and sophisticated account yet of the physical Universe and the essentials of its underlying mathematical description. Penrose neither simplifies the science nor dodges the difficult questions, but instead tackles all the issues and controversies, including: the role of numbers in physics, ideas of calculus and modern geometry, visions of infinity, the Big Bang, black holes, the profound challenge of the second law of thermodynamics, String Theory and more. The exposition also highlights the awesome beauty of contemporary Physics and Mathematics.
    • March 10, 2005 | 1:00 PM | LASR 213 | Special seminar
      Watching galaxies assemble: cosmological star formation and mass assembly history form SDSS spectra
      Raul Jimenez, University of Pennsylvania

     
    THURSDAY LUNCH DISCUSSIONS

    • February 17, 2005 | 1:00 PM | LASR Conference Room | Thursday lunch discussion
      What is the Cosmological Significance of a Discovery of Wimps at Colliders or in Direct Experiments?
      Jacob Bourjaily, University of Michigan

      Although a discovery of wimps either at colliders or in direct experiments would have enormous implications for our understanding of particle physics, it would imply less than one would like about our understanding of the dark matter in the universe or in the galactic halo: it surely is possible that discovered particles account for only a little of the total dark matter. To establish the cosmological significance of a wimp discovery, their density must be determined. I will show that data from neither hadron colliders nor direct detection experiments alone can be sufficient to determine the local or relic density of discovered wimps, even allowing all needed assumptions about cosmology and astrophysics. However, it may be possible to determine the density of wimps by combining data from both experiments. I present a general method to do this in the case of supersymmetric dark matter, and describe how similar studies could be made for other wimp candidates.

     
    ASTRONOMY SPECIAL SEMINARS

    • March 2, 2005 | 12:00 PM | RI 480 | Special Seminar
      Understanding High-Redshift Galaxy Clusters as Cosmological Probes: Recent Results and Instrumentation Developments
      Mike Gladders, Carnegie Observatories