FEBRUARY 4 - 8, 2008

TUESDAY, FEBRUARY 5

2:30 pm: Joint MIT/CfA/Tufts Cosmology Seminar. "The Origin of the Highest Energy Particles," Prof. Angela Olinto, University of Chicago. Phillips Auditorium.

Abstract: After almost a century of observations, the ultra-high energy sky has finally displayed an anisotropic distribution. A significant correlation between the arrival directions of ultra-high cosmic rays measured by the Pierre Auger Observatory and the distribution of nearby active galactic nuclei signals the dawn of particle astronomy. These historic results have important implications to both astrophysics and particle physics.

WEDNESDAY, FEBRUARY 6

12:30 pm: High Energy Astrophysics Division Lunch Talk. "X-ray Spectral Evolution of Very High Energy Emission from TeV BL Lacs," Dr. Francesco Massaro, CfA. Pratt Conference Room.

Abstract: Many of the extragalactic sources detected in gamma rays at TeV energies are BL Lac objects. In particular, they belong to the subclass of "high frequency peaked BL Lacs" (HBLs), as their spectral energy distributions exhibit the synchrotron peak in the X-ray band. At a closer look, their X-ray spectra appear to be generally curved into a log-parabolic shape, in terms of three parameters: the SED energy peak, the height of the SED at this energy and the curvature. In a previous investigation of Mrk 421, based on a sample of observation spanned over eleven years, two correlations were found between these spectral parameters and they have been interpreted in terms of synchrotron emission from relativistic electrons, accelerated in statistic/ stochastic processes. Subsequently, the whole sample of X-ray observations of all TeV HBLs, obtained with the BeppoSAX, XMM-Newton and Swift satellites have been considered for a similar analysis of their behaviour. I focus on five sources whose X-ray observations warrant detailed searching of correlations or trends. I found that four out of five sources, namely PKS 0548-322, 1H 1426+418, Mrk 501 and 1ES 1959+650, follow similar trends as Mrk 421 while PKS 2155-304 differs. The trends can be useful to warrant discussing predictions from the X- ray spectral evolution to that of TeV emissions.

4:00 pm: Initiative in Innovative Computing (IIC) Seminar. "De-constructing Cyberinfrastructure," Dr. Fran Berman, Director, San Diego Supercomputer Center and Professor, High Performance Computing Endowed Chair, UC San Diego. Preceded by refreshments at 3:45 pm. Room 330, 60 Oxford Street, Cambridge. Event parking is available at the 52 Oxford Street Garage [map]. Please inform the parking attendant you are attending the IIC seminar. (The IIC seminar series schedule is updated often with additional information and seminars.)

Abstract: Cyberinfrastructure, the integrated framework of enabling information and computational technologies, experts, and tools, has emerged as a foundation for applications in the Information Age. The vision of Cyberinfrastructure is powerful and important, yet designing, building, deploying, evaluating, and funding capable, useful, and usable Cyberinfrastructure is a an immense challenge. In this talk, San Diego Supercomputer Center Director Fran Berman discusses the challenges and opportunities of building and deploying Cyberinfrastructure as a continuous bootstrapping process that furthers both scientific progress and technology capability.

THURSDAY, FEBRUARY 7

11:00 am: Institute for Theory and Computation (ITC) Colloquium. "Evolution of Galaxies: Emerging Insights and Future Challenges," Shardha Jogee, University of Texas, Austin. Pratt Conference Room.

Abstract: Hierarchical LCDM models provide one of the most successful paradigms for the growth of dark matter on large scales, but important challenges remain in understanding how the baryonic components of galaxies evolve. I will outline several areas of discord. I will discuss complementary insights, which are being gleaned from large and deep surveys that we and other teams are conducting (e.g. GEMS, GOODS, AEGIS, COSMOS, STAGES Abell 901/902 supercluster, ACS Treasury Survey of the Coma cluster) in order to explore galaxies at different epochs and in different environments. I will present results on the merger history of galaxies since z < 3 and the impact of galaxy interactions/mergers on the cosmic star formation rate density. Comparisons with LCDM models will be presented. I will also discuss the ever-increasing importance of secular processes at z < 1, the structural assembly of galaxy components (bulges, bars, and disks), and the problem of bulgeless galaxies. In conclusion, we will discuss challenges that can be resolved by future facilities such as WFPC3 on HST, the Atacama Large Millimeter Array (ALMA), the James Webb Space Telescope (JWST), and large ground-based telescopes.

4:00 pm: Colloquium. "High-Energy Neutrino Astronomy: Towards a Kilometer-Scale Neutrino Observatory," Prof. Francis Halzen, University of Wisconsin. (Anyone wishing to meet with the speaker should contact the host, Dr. Andrew Szentgyorgyi, ext. 5-5-7397.) Preceded by tea at 3:30 pm. Phillips Auditorium.

Abstract: Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10²⁰ and 10¹³ electronvolts, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. The problem has been to develop a robust and affordable technology to build the kilometer-scale neutrino detectors required to do the science. The AMANDA telescope using clear deep Antarctic ice as a Cherenkov detector of muons and showers initiated by neutrinos of all 3 flavors, has met this challenge. Having collected more than 5000 well-reconstructed muon neutrinos in the 50 GeV ~ 500 TeV energy, AMANDA represents a proof of concept for the ultimate kilometer-scale neutrino observatory, IceCube, now almost half complete and taking data.

SAO HUMAN RESOURCES NOTES

Leave Donations Requested

Due to a medical emergency, Joyce Janjigian of the Solar, Stellar and Planetary Science Division has been approved as a leave donor recipient in the Leave Transfer Program. Any SAO Trust Fund employee who wishes to donate annual leave to Joyce should complete a Leave Donor Form and send it to MS 17.

Under the Leave Transfer Program, Trust Fund employees may only donate annual leave to other Trust Fund employees and Federal employees may donate annual leave only to other Federal employees. If you should have any questions or are not able to access the form, please contact Anne LeBlanc, ext. 5-7371.

Job Vacancies

An online listing of all current SAO job openings is available. For more information, please call Human Resources, ext. 5-7371, or view your nearest bulletin board.