GCGM5 Schedule

338 Johnston Hall

 Friday, April 17, 2009:

12:30-13:00    Registration
13:00-13:30    Welcome + Practical information

Session 1:

13:30-13:50:    Konstantin Yakunin "Gravitational Waves from Core Collapse Supernova "
13:50-14:10:    Yan Wang (S) "Strong field effects on pulsar arrival times "
14:10-14:30:    Argenis Da Silva (S) "Evolution of Electrically Charged and Anisotropic Stars "

14:30-15:00:    Refreshments

Session 2:

15:00-15:20:    Tyler Landis (S) "General Relativistic Magnetohydrodynamics on Multiple Patches "
15:20-15:40:    Oleg Korobkin (S) "Dynamical Nonaxisymmetric Instabilities in Relativistic Self-Gravitating Disks "
15:40-16:00:    Miguel Megevand (S) "Effects of recoiling black holes on surrounding disks "
16:00-16:20:    Roland Haas "Black Hole - Neutron Star Binary Simulations at Georgia Tech "

16:20-16:40:    Break

Session 3:

16:40-17:00:    Usama al-Binni (S) "Particle emission from a black hole on a codimension-2 brane "
17:00-17:20:    Jeff Kissel (S) "The Present and Near Future of LIGO "
17:20-17:40:    Gabriela Gonzalez, for the LSC "Calibration of the LIGO detectors "


Saturday, April 18, 2009:

9:00-9:30:    Coffee

Session 4:

9:30-9:50:    David Brown "Probing the puncture for black hole simulations "
9:50-10:10:    Travis Garrett "Scalar Fields and Moving Punctures "
10:10-10:30:    Richard Price "New numerics for the helicallly symmetric standing wave approximation"

10:30-11:00:    Break

Session 5:

11:00-11:20:    Jacob Slutsky (S) "Data quality and vetoes in searches for compact binary coalescences in LIGO's fifth science run "
11:20-11:40:    Amber Stuver "LOOC-UP: A LIGO-Virgo Gravitational Wave Observation "
11:40-12:00:    Rupal Amin (S) "Thermal Compensation in LIGO "

12:00-13:30:    Lunch

Session 6:

13:30-13:50    Myungkee Sung "Search for Burst Type Gravitational Wave in the LIGO Experiment "
13:50-14:10    Cesar Costa "Adaptive Filters: Transients and System Change Detection on LIGO Auxiliary Channels "
14:10-14:30    Sarah Caudill (S) "Estimating the Accidental Coincidence Rates in Searches for Gravitational Waves from Compact Binary Coalescences with LIGO "

14:30-15:00:   Refreshments

Session 7:

ABSTRACTS

Usama al-Binni

Abstract:  Particle emission from a black hole on a codimension-2 brane    
I will present results for analytical calculations of grey-body factors of Schwarzschild black-holes localized on a 3-brane of finite tension and codimension 2. The results are obtained for various types of particles emitted in the bulk as well as on the brane in both the low and high frequency regimes. In the latter case, the expressions are valid for arbitrary number of extra dimensions if the brane tension vanishes.

Rupal Amin

Abstract:   Thermal Compensation in LIGO 
Initial LIGO and Enhanced LIGO possess optics that impose self-induced thermal aberrations on the main laser light and its radio frequncy sidebands.  These effects driven by mirror absorption lead to failures in interferometer power build-up and loss of control signal strength especially in the power recycling cavity. A thermal compensation system (TCS) comprised of auxillary heating lasers aided initial LIGO with optical stability at 8 W injected power. Enhanced LIGO faces larger thermal difficulties at above 8 W.  Additionally control signals available during initial LIGO will be removed.  Consequently a model comprised of a commercial FEM program and an in-house interferometer simulator is being constructed to predict interferometer response to the Enhanced LIGO TCS. Furthermore, we hope to discover new figures of merit to optimize TCS settings during high power operation.

Eloisa Bentivegna

Abstract: Quasi-local angular momentum estimates via constant-expansion surfaces    
Notions like energy and angular momentum and the associated conservation laws play an invaluable role in Newtonian dynamics. In General Relativity, however, the estimate of angular momentum and other physical observables is complicated by a number of factors, such as their non-localizability and the ambiguities in defining a reference frame in which to measure them. Most of these issues seriously affect numerical simulations, where only portions of a spacetime are usually accessible, and one has very little control over the coordinates used and their evolution. I will discuss how surfaces of constant expansion show the potential to alleviate these problems.

David Brown

Abstract: Probing the puncture for black hole simulations    
I will discuss some work in progress toward understanding the puncture recipe for black hole simulations.

Sarah Caudill

Abstract:   Estimating the Accidental Coincidence Rates in Searches for Gravitational Waves from Compact Binary Coalescences with LIGO  
In order to estimate accidental coincidence rates for the gravitational wave candidates found at the end of LIGO's inspiral search pipelines, the method of time-shifted data is used, where a number of time-shifted data streams are analyzed to provide accidental coincidence rates for candidates with a given signal-to-noise ratio. This method unfortunately provides poor estimation of rates for high signal-to-noise ratio candidates. We will present a proposal for improving the estimation of accidental coincidence rates, using the rate of triggers found in each detector before coincidence is used.

Cesar Costa

Abstract:    Adaptive Filters: Transients and System Change Detection on LIGO Auxiliary Channels 
Adaptive filters are known for being able to adjust themselves to unknown environments, and even track signal or system proprieties varying along time. This talk presents a method to detect sudden changes in dynamic systems by using adaptive filters and cumulative log-likelihood sum. The main idea in this work is determine how the coefficients behave when sudden changes (glitches) occur in the system, how the criteria would be for determining a detection of such events, and how those tools can be applied to LIGO auxiliary channels.

Argenis Da Silva

Abstract:  Evolution of Ellectrically Charged and Anisotropic Stars   
I use the method of the effective variables to study the evolution of spherical, electrically charged, anisotropic stars. I present some numerical results.

Peter Diener

Abstract:   Self force calculations using a 3D finite differencing code  
I will show results for the calculation of the self force on a scalar point charge in circular orbit around a Schwarzschild black hole
using a 3D multi-block finite differencing code. The code uses the field regularization technique of Vega and Detweiler and thus
avoids direct calculations of the singular part of the field. The scalar field is regular and the self force can be calculated at the location of
the particle.

Travis Garrett

Abstract:    Scalar Fields and Moving Punctures 
We describe our current research on adding scalar fields to black hole simulations in the BSSN framework.

Gabriela Gonzalez

Abstract:    Calibration of the LIGO detectors 
I will present the basics of how the LIGO detectors have calibrated their data in the last science data-taking run S5 (Nov 2005-October 2007), which achieved the detectors' initial design sensitivity. I will also discuss the estimated error in such calibration

Roland Haas 

Abstract:    Black Hole - Neutron Star Binary Simulations at Georgia Tech  
Mixed compact object binaries consisting of a black hole and a neutron star are expected to be not only one of the primary
sources of gravitational radiation to be observed by interferometric detectors but also the central engine of short gamma-ray bursts.  We report on the status of our effort at Georgia Tech to model these mixed binary systems using the moving puncture method. The results are obtained with an enhanced version our vacuum MayaKranc code coupled to the hydrodynamics Whisky code. We present preliminary results of gravitational waveforms and the disruption of the neutron star for simple polytropic equations of state.

Jeffrey Kissel

Abstract:    The Present and Near Future of LIGO
The two 4 km arm laser interferometric gravitational wave observatories (LIGO) are virtually finished with their first set of upgrades called "Enhanced LIGO." Much of the design for Advanced LIGO, the next much more impressive set of upgrades is finished as well. In this presentation, I'll describe the upgrades completed for Enhanced and planned for Advanced LIGO, present recent accomplishments and goals for the detectors' displacement sensitivity, and include projected time tables for completion.

Oleg Korobkin

Abstract:  Dynamical Nonaxisymmetric Instabilities in Relativistic Self-Gravitating Disks
Massive relativistic self-gravitating disks appear as transient structures in several astrophysical scenarios, such as a
merger involving a neutron star, or a supernova core collapse. Although these objects are short-lived, they might play an important
role in understanding the mechanism of gamma-ray bursts.  The viability of some models of gamma-ray burst engines depend on the
stability of massive self-gravitating disks around black holes.  We present results from numerical evolutions of perturbed
self-gravitating equilibrium tori and discuss the nature of observed non-axisymmetric instabilities.  The numerical simulations feature
fully dynamical 3-dimensional background.

Tyler Landis

Abstract:    General Relativistic Magnetohydrodynamics on Multiple Patches
We have been developing a code to simulate compact astrophysical systems such as black hole accretion disk systems believed to power many astrophysical jets. I will discuss the current status of the code including tests on fixed backgrounds and our treatment of the magnetic field.

Miguel Megevand

Abstract:   Effects of recoiling black holes on surrounding disks  
The dynamics of a binary black hole can give rise to a final black hole with a recoil velocity.  When a circumbinary disk is present, it will be disturbed by the recoiling black hole, possibly producing shocks and heating the gas. The hot gas can produce electromagnetic radiation through a variety of processes.  In this work we study the effects of a recoiling black hole on a thick gaseous disk.

Richard Price

Abstract:  New numerics for the helicallly symmetric standing wave approximation   
The periodic standing wave project uses information from a helically symmetric standing wave solution of Einstein's equations as an
approximation to the physical problem of a slowly decaying orbi with outgoing waves. The work has now been completed on computations of solutions using specialized coordinates, and is underway on a much more accurate spectral approach.

Erik Schnetter

Abstract:    Community Infrastructure for General Relativistic MHD (CIGR) 
The "Community Infrastructure for General Relativistic MHD" (CIGR) project plans to create a modern, scalable, open community toolkit for general relativistic magnetohydrodynamics (GRMHD).  This toolkit will be able to integrate new science modules for the treatment of general relativistic hydrodynamics, microphysical equations of state, magnetohydrodynamics, and radiation transport.  The effort will build on accumulated experience with the Cactus framework, the Carpet adaptive mesh refinement driver, and the Whisky code.  This continues the development of the Einstein Toolkit, which already provides interoperability for initial data and analysis methods such as horizon finding, and is used very successfully by various research groups.

Jacob Slutsky

Abstract: Data quality and vetoes in searches for compact binary coalescences in  LIGO's fifth science run    
Searches for gravitational waves from compact binary coalescences (CBCs), are hindered by the presence of transient detector noise, which can produce false alarms. Using auxiliary channels and the gravitational wave channel itself, the LIGO Scientific Collaboration has identified a variety of instrumental and environmental artifacts that lead to false signals. We find time intervals affected by these artifacts, and use them as vetoes for CBC and Burst searches in LIGO's fifth science run.

Amber Stuver

Abstract:     LOOC-UP: A LIGO-Virgo Gravitational Wave Observation Initiated Multi-messenger Astronomy Project  
Within the LIGO and Virgo Collaborations, the LOOC-UP project is being developed to implement the rapid electromagnetic (EM) follow-up of candidate gravitational wave events starting during the S6/VSR2 science run.  The application of such follow-ups will provide support for any detection of gravitational waves during this science run and provide valuable experience for mature EM follow-up applications during Advanced LIGO.  Collaborations with EM observatories are being established to open a communication channel with the gravitational wave (GW) observatories and to define target of opportunity observing allowances.  The LOOC-UP control and monitoring software, LUMIN, is also under development.  This software begins by taking in parameters, such as source location estimates, from near real-time coincident events between detectors and determining which of the participating EM observatories will be able to image the source area and when.  Once a human vets the candidate GW event, this information is then communicated to the EM observatories.  The source area will then be imaged and analyzed to search for EM transients that may be the counterpart to the GW source.  Once the LUMIN infrastructure is mature, it will be fully automated eliminating the need for human interaction.  This multi-messenger astronomy approach to the search for gravitational waves is an important step in the development of GW astronomy and is essential for Advanced LIGO and Virgo when many gravitational wave detections are expected.  (LIGO-G0900328)

Myungkee Sung

Abstract:  Search for Burst Type Gravitational Wave in the LIGO Experiment
The LIGO detectors have collected data with design sensitivity for about two calender year (November 2005 - October 2007). Transient gravitational-wave signals are expected from astrophysical bursts, such as core-collapse supernovae, the merger phase of coalescing binary compact stars and gamma-ray bursts. Searches for these burst type signals are performed with various methods, which have been developed to look for short duration and unknown waveforms. All-sky searches for burst signals have been done using the recent LIGO data with multiple methods. In addition, using information from other astrophysical observations, search analyses focusing on the gravitational wave signals related to observed astrophysical events are also being performed. In this presentation, I will describe the various analyses of burst searchs in the LIGO experiment and the techniques used.

Cristina Torres

Abstract:  Detection confidence tests for Inspiral Candidate Events     
In order to detect gravitational-wave signals from compact binary inspiral systems in the data from the LIGO detectors the LSC-Virgo
Compact Binary Coalescence(CBC) group has developed  an analysis method based on optimal matched filtering. In order to confirm the
possible discovery of gravitational waves, the CBC group has developed a detection checklist intended to validate the statistically
significant candidate events produced by the CBC analysis. The detection checklist is a series of additional tests geared to
corroborating a detection or to identifying a false alarm. We practice this checklist with the loudest candidates found (even if not
statistically significant) and with simulated signals. In this talk we will present the methodology used for candidate validation.

Yan Wang

Abstract:  Strong field effects on pulsar arrival times   
The strong gravitational field near a supermassive black hole affects paths and intensities of EM signals passing through it. Thus if a pulsar orbits a supermassive black hole, the timing and the intensity detected by a far field observer will exhibit a set of variances. We developed a formalism based on two "universal functions," one for the bending of photon trajectories and the other for the photon travel time on these trajectories. Though these can be, and are being applied to any non-rotating supermassive black hole case, we have initially used them to understand equatorial beams in circular orbits. This simple case exhibits many of the features expected more generally.

Konstantin Yakunin

Abstract:  Gravitational Waves from Core Collapse Supernova   
We perform numerical simulations of Core Collapse Supernova using the multi-dimensional hydrodynamics code CHIMERA The code can handle realistic nuclear reactions as well as spectral neutrino transport coupled with fluid motions. We present gravitational wave templates generated by both barionic matter and neutrino emission for progenitor stars with different masses.