LIGO - Fermi Sub-Threshold Search - PowerPoint Presentation

Slide1

LIGO - Fermi Sub-Threshold Search

for the 1

st

Advanced LIGO Science Run

Jordan Camp

NASA Goddard Space Flight Center

Moriond

Gravitation Meeting

March 25, 2015

Search Team

Lindy 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)Slide2

Advanced LIGO is now operating

Washington

Louisiana

Gravitational Wave causes differential arm displacement



photodetector

signalSlide3

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 LIGO

Initial LIGO BNS range

20

Mpc

Advanced LIGO BNS

range 200

Mpc

(Washington 28

Mpc

, Louisiana 68

Mpc

)Slide4

Recent LIGO Noise Spectrum

Initial LIGO, 20

Mpc

Advanced LIGO, 59

Mpc

Design Sensitivity, 138

Mpc

(Laser power = 25 W)

O1 run this summer

Slide5

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 earthSlide6

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

4

p

FoV

2

p

FoV

100 deg

2

25 deg

2Slide7

Coherent Analysis of GBM Detectors

(L. Blackburn and UAH)

signal

noise

data

Instrument response

source

Evaluate

L

by marginalizing over

source

amplitude, position

r

i

provided by GBM detector model (

Connaughton

, UAH)

Factor

2 gain in SNRSlide8

8

Test of Initial LIGO – GBM coincident analysis

L. Blackburn,

ApJ S 217 (2015)

ASM

GBM

LIGO BNS trigger

LIGO sky localizationSlide9

9

sGRB Precursors and NS EOS

E.

Troja et al, Ap J 723 (2010)

Slide10

NS Crust Resonant Shattering Process

Tsang et al, PRL 108 (2012)

10

Mode Energy

~ 10

47

erg Fracture

Seismic Energy~ 10

46 erg Shattering

Luminosity ~ 10

46-47

erg 0.1 sec

(can see 10

47

erg at ~ 150

Mpc

)

Isotropic (!)

Available Tidal Energy

~ 10

50

ergSlide11

11

Investigating NS Crust Equation of State

f

res

(from GW)

at time of Precursor 

NS EoSSlide12

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, O3Slide13

O1 LIGO – GBM Search

O1 run around fall 2015

3 months

Hanford and Livingston detector range > 60 MpcPipeline development

Further tests of GBM coherent analysisUse GBM continuous data from every downlink (CTTE)LIGO sky localization: low-latency to enable real-time alerts

Run pipelineAnalyze results and get ready for O2

run at > 100 MpcContinue development of GBM coherent analysis (UAH)