ligo - fermi sub-threshold search for the 1 st advanced ligo science run jordan camp nasa goddard...
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LIGO - Fermi Sub-Threshold Searchfor the 1st Advanced LIGO Science Run
Jordan CampNASA Goddard Space Flight Center
Moriond Gravitation MeetingMarch 25, 2015
Search TeamLindy Blackburn (CfA)
Nelson Christensen (Carleton College)Valerie Connaughton, Michael Briggs, Binbin Zhang (UAH)
Peter Shawhan (U Md) Leo Singer (Goddard NPP)
John Veitch (U Birmingham)
Advanced LIGO is now operating
Washington Louisiana
Gravitational Wave causes differential arm displacement photodetector signal
Advanced LIGO Sensitivity Goal
• Factor 10 lower noise at high frequency• Higher power laser
• Factor 10 lower noise at low frequency• Active seismic isolation
• Factor 6 lower cutoff frequency • Multiple suspensions in series Advanced LIG
O
Initial LIGO BNS range 20 Mpc
Advanced LIGO BNS range 200 Mpc
(Washington 28 Mpc, Louisiana 68 Mpc)
Recent LIGO Noise Spectrum
Initial LIGO, 20 Mpc
Advanced LIGO, 59 Mpc
Design Sensitivity, 138 Mpc(Laser power = 25 W)
O1 run this summer
Short Gamma-Ray Burst
sGRB
Fermi
• sGRB is most likely due to merging of Neutron Stars• Inspiral of NS – NS produces GW, merger produces burst of Gamma-rays• Excellent candidate for coincident detection of GW and Gamma-ray• Overlap of GW/Gamma-ray in time and location subthreshold detection
• > 100 sGRBs observed by Fermi Gamma-Ray Burst Monitor (GBM)• 12 Na I detectors in varying orientations, 5 degree position resolution• GW is roughly isotropic, but Gamma-ray is beamed (10 degree opening)• Need sGRB within LIGO horizon (400 Mpc), and beamed at earth
LIGO – GBM Coincident Search
• GBM coincidence in time and space will help verify the GW event• Followup of GBM with eg Palomar Transient Facility localization• host galaxy, redshift, accurate BNS parameter extraction
• Relative timing of Gamma-ray and GW mass of Graviton• Energetics, beaming, and nature of sGRB• Information on NS Equation of State ?
NS-NS merger: Short Gamma-Ray Burst (sGRB)
LIGO Fermi GBM GWs Gamma-rays
4p FoV 2p FoV100 deg225 deg2
Coherent Analysis of GBM Detectors(L. Blackburn and UAH)
signal
noise
data
Instrument response
source
Evaluate L by marginalizing over source amplitude, position
ri provided by GBM detector model (Connaughton, UAH)
Factor 2 gain in SNR
8
Test of Initial LIGO – GBM coincident analysisL. Blackburn, ApJ S 217 (2015)
ASM GBM
LIGO BNS triggerLIGO sky localization
NS Crust Resonant Shattering Process Tsang et al, PRL 108 (2012)
10
Mode Energy ~ 1047 erg Fracture
Seismic Energy~ 1046 erg Shattering
Luminosity ~ 1046-47 erg 0.1 sec(can see 1047 erg at ~ 150 Mpc)
Isotropic (!)
Available Tidal Energy~ 1050 erg
Optimistic O1 LIGO and sGRB Rates
aLIGO BNS Detections
sGRB Detections
Typical jet angle ~ 10 degree beaming factor ~ 100
Thus 3 LIGO BNS detections ~ 0.03 coincident sGRB detection ~ 0.3 (subthreshold/GW on jet axis)
Realistic rates likely to be factor 10 lower… look to O2, O3
O1 LIGO – GBM Search
• O1 run around fall 2015– 3 months– Hanford and Livingston detector range > 60 Mpc
• Pipeline development– Further tests of GBM coherent analysis– Use GBM continuous data from every downlink (CTTE)– LIGO sky localization: low-latency to enable real-time alerts
• Run pipeline– Analyze results and get ready for O2 run at > 100 Mpc– Continue development of GBM coherent analysis (UAH)
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