Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session E8: Gamma Ray Bursts, Gravitational Wave Bursts, Supernovae |
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Sponsoring Units: GGR DAP Chair: Erik Katsavounidis, Massachusetts Institute of Technology Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Promenade A |
Saturday, April 12, 2008 3:30PM - 3:42PM |
E8.00001: Relativistic Particle-In-Cell Simulation Studies of Prompt and Early Afterglows from GRBs Ken-Ichi Nishikawa, Philip Hardee, Yosuke Mizuno, Gerald Fishman Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The ``jitter'' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. [Preview Abstract] |
Saturday, April 12, 2008 3:42PM - 3:54PM |
E8.00002: A Blind Search for Transient Bursts of Very High Energy $\gamma$-rays using Milagro gamma-Rays Using Milagro Vlasios Vasileiou Milagro is a water-Cherenkov detector capable of observing air showers produced by $\gamma$ rays. The wide field of view ($\sim$2 sr) and high duty cycle ($>$90\%) of Milagro make it ideal for searching for transient very high energy emission. We will report on the results of a blind search of the Milagro data for very high energy $\gamma$-ray outbursts within the Milagro field of view for durations ranging from 1ms to 6 minutes. While this analysis is primarily aimed at detecting $\gamma$-ray bursts (GRBs), it could also be sensitive to other phenomena like primordial black-hole evaporation and soft $\gamma$-ray repeaters. No trigger from another instrument is required, instead the entire reconstructed data set is systematically searched in time, space and emission duration. Four years of Milagro data are searched, which corresponds to 2920~sr days of exposure. While the peak sensitivity of Milagro is above 1 TeV, the detector has substantial effective area at lower energies ($\sim$50 m$^2$ at 100 GeV, $\sim$2500 m$^2$ at 1 TeV). [Preview Abstract] |
Saturday, April 12, 2008 3:54PM - 4:06PM |
E8.00003: Acceleration and survival of ultrahigh-energy cosmic-ray nuclei in gamma-ray bursts and hypernovae Soebur Razzaque Recent results from the Pierre Auger Observatory hint that ultrahigh-energy cosmic-rays above an EeV energy may be composed of heavy nuclei rather than nucleons. This naturally leads to the questions of their origin and acceleration at the astrophysical objects. Gamma-ray bursts and hypernovae have been proposed to be the sources of ultrahigh-energy cosmic-rays. We explore different physical conditions under which heavy nuclei may be accelerated and survive in the environment of these sources, and report our findings. [Preview Abstract] |
Saturday, April 12, 2008 4:06PM - 4:18PM |
E8.00004: Searches for gravitational-wave inspirals from short GRBs Nickolas Fotopoulos Short Gamma Ray Bursts (GRBs) are widely believed to be produced in the merger of a double neutron star binary or a neutron star-black hole binary. Such systems produce strong gravitational waves, which could be detectable by the Laser Interferometer Gravitational-wave Observatory (LIGO). Because the time and the location of such an event is known, LIGO data can be searched in coincidence with a GRB with a lower threshold than previous untriggered searches. We present the results of a search for compact binary inspirals in LIGO data around GRB 070201 and plans for extending this search to other GRBs that occurred during LIGO's latest science run. [Preview Abstract] |
Saturday, April 12, 2008 4:18PM - 4:30PM |
E8.00005: Coherent Network Searches for Gravitational Waves associated with Gamma-Ray Bursts Gareth Jones Over 200 gamma-ray bursts (GRBs) were observed electromagnetically during the LIGO science run 5 / Virgo science run 1. Attempts to detect gravitational waves (GWs) associated with GRBs can take advantage of the known sky position and time of the GRB to increase the sensitivity of the search. Coherent analysis methods are particularly well-suited to such directional searches. They use the known sky position to construct linear combinations of the data that maximize or minimize the SNR of a GW signal with a given polarization. This allows for both high sensitivity to real GWs and powerful consistency tests for eliminating background noise, without a priori assumptions on the GW waveform. We discuss prospects for GRB-GW searches with data taken during the LIGO science run 5 / Virgo science run 1. [Preview Abstract] |
Saturday, April 12, 2008 4:30PM - 4:42PM |
E8.00006: Analysis Method to Search for Coincidence Events between the LIGO-Virgo Gravitational-wave Detector Network and the IceCube Neutrino Detector Yoichi Aso, Chad Finley, Zsuzsa Marka, John Dwyer, Kei Kotake, Szabolcs Marka Violent astrophysical phenomena such as gamma-ray bursts may produce gravitational wave emission along with high energy neutrinos. A network of gravitational wave detectors such as LIGO and Virgo can determine the direction of gravitational wave bursts while the IceCube neutrino detector can also provide accurate directional information for neutrino events above 100GeV. By combining timing and directional information of events from these two independent detectors, we can search for coincident events that may arrive from common astrophysical sources. The coincidence analysis reduces the false alarm rate, and this in turn allows the trigger threshold to be relaxed and improves the ability to detect a shared class of sources. While the method can be applied to various combinations of detectors, we will present our method specifically for the case of the LIGO-Virgo network and IceCube, using the results of Monte Carlo simulations to demonstrate its performance. [Preview Abstract] |
Saturday, April 12, 2008 4:42PM - 4:54PM |
E8.00007: Gravitational waves from core-collapse supernova using CHIMERA Konstantin Yakunin, Stephen Bruenn, Pedro Marronetti, Shin Yoshida We perform numerical simulations of core-collapse supernova using the multi-dimensional hydrodynamics code CHIMERA that includes realistic nuclear reactions as well as spectral neutrino transport. We present gravitational wave signals from progenitor stars with different rotational profiles, studying the effects of neutrino radiation in the emission of gravitational waves. These GW templates can be used to enhance the search for supernovae signals in current and future GW detectors. [Preview Abstract] |
Saturday, April 12, 2008 4:54PM - 5:06PM |
E8.00008: Search for transient gravitational waves associated with Soft Gamma Repeaters using the LIGO detectors Peter Kalmus During part of LIGO's fifth science run from November 2005 to May 2007, satellite-based gamma-ray detectors observed more than 200 bursts from the Soft Gamma Repeaters SGR 1806-20 and SGR 1900+14. These objects are located within our galaxy and their sky locations are known to high precision. Models predict gravitational wave emission via excitation of non-radial modes in the compact source, making them plausible targets for a gravitational wave search. The majority of the SGR events occurred while multiple LIGO detectors were collecting data with high sensitivity. We present the status of the search for transient gravitational waves associated with SGR events using coherent combination of data from multiple LIGO detectors. Coherent methods can be used to search for any transient gravitational wave signal in the band 100-3000 Hz, including neutron star ringdowns. Upper limits on gravitational wave emission energies can be estimated using simulated white noise burst and ringdown waveforms. [Preview Abstract] |
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