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

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Test of Initial LIGO – GBM coincident analysisL. Blackburn, ApJ S 217 (2015)

ASM GBM

LIGO BNS triggerLIGO sky localization

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sGRB Precursors and NS EOSE. Troja et al, Ap J 723 (2010)

NS Crust Resonant Shattering Process Tsang et al, PRL 108 (2012)

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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

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Investigating NS Crust Equation of State

fres (from GW) at time of Precursor NS EoS

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)