Search For Unmodeled Gravitational Waves From Sco X-1

People

• Kazuhiro Hayama, Chris Messenger (Albert Einstein Institut at Hannover)
• in collaboration with Ed Morgan (MIT), Soumya Mohanty (Univ. of Texas, Brownsville), Sergey Klimenko (Univ. of Florida), and

Hot Topic

• LIGO-RXTE coincidence search for GWs from Sco X-1: at Amaldi8
• Report at RXTE telecon (9 July, 2009)

Project Description

Scientific goals

• To constrain gravitational wave flux from Sco X-1
• To infer spin frequency of Sco X-1
• ...

Data sets

• RXTE-H1(H2),L1 S5 coincident data (~ 1 day)
  
  • RXTE-H1-H2-L1 coincident data GPS list (Rough version, NOT for analysis)
    
  • Durations of RXTE science segments Plot
    
  • Accumulation of RXTE science segments Plot
    

Analysis approach

• Coincidence analysis between RXTE triggers and gravitational wave(GW) triggers.
  • GW triggers : Source tracking approach based on cohelent WaveBurst will be used. The sky location of Sco X-1 is moving 0.25 degrees/minute along with the longitude. Data is divided into one minute long segments and analyze likelihood sky-maps around the location of Sco X-1.
  • RXTE triggers : Excess power approach on the time-frequency space.
• Output1 (Upper limit on GW flux):
  • GW flux for each GW trigger is calculated with some assumptions by analyzing 0-lag data. Repeat the same analysis using 1,2,3,.. lag data. Significance of 0-lag events are obtained. Upper limit on GW flux can be calculated.
  • Taking coincidence between RXTE triggers and GW triggers of 0-lag event, Upper limit on GW flux can be improved.
• Output2 (Infer the spin frequency of Sco X-1)
  • Let us assume the theory by Wagoner (1984), Bildsten (1998) that in LMXBs torque is balanced by gravitational waves according to Fgw=fspin/fkepler*Fx. Since emitting gravitational wave is not necessary continuous, we consider of un-modeled gravitational waves for balancing torque. fspin can be constrained from observational estimation of Fgw and Fx.

Analysis

Software

• wat 4.7.3

Task

Presentations

• LIGO-RXTE coincidence search for GWs from Sco X-1: at Amaldi8
• Report at Burst telecon (10 June, 2009)
• Report at Exttrig telecon (31 March, 2009)
• Source tracking for Sco X-1: at GWDAW12
• A method for searching for gravitational waves triggered by astronomical observations: at TAUP2007

Published Papers

• Source Tracking for Sco X-1(pdf)
• Monitoring Sco X-1 for the detection of gravitational waves with networks of gravitational wave detectors ( pdf)
• A coherent method for detection of gravitational wave bursts (pdf)
• Constraint likelihood analysis for a network of gravitational wave detectors (pdf)
• Coherent network analysis for triggered gravitational wave burst searches (pdf)

Technical Papers

• WaveBurst: S5 version (pdf)
• Coherent WaveBurst - WAT version 4.7.0 (pdf)

Related Documents

• The Rossi X-ray Timing Explorer Mission in NASA
• Upper limit map of a background of gravitational waves (LSC, 2007)
• Searches for periodic gravitational waves from unknown isolated sources and Scorpius X-1: Results from the second LIGO science run (LSC, 2007)
• Gravitational radiation from accreting neutron stars (R.V. Wagoner, 1984)
• Gravitational Radiation and Rotation of Accreting Neutron Stars (L. Bildsten, 1998)
• Gravitational wave bursts induced by r-mode spin-down of hybrid stars
• Possible sources of gravitational wave bursts detectable today
• A Timing Signature of Gravitational Radiation from LMXB Neutron Stars