1. Search for signature of the LIGO gravitational wave events in SPI-ACS and GBM/Fermi
Alexei Pozanenko, Pavel Minaev,
Maxim Barkov, Maxim Toropov, Vladimir Loznikov
Space Research Institute (IKI), Moscow
HEPRO-6

2. "Elephant in the room"

3. Outline Observations: comparison of sensitivity for short GRBs
No evident GRB-like event is found for published LIGO BH-BH GW150914, GW151226, LVT151012, GW170104
Most sensitive omnidirectional GRB experiments = GBM/Fermi and SPI-ACS/INTEGRAL
Searching for quasi-periodic transient events
Special case of GW150914
comparison of sensitivity for short GRBs
How to reconcile GBM/Fermi and SPI-ACS observations?
Speculations:
BH-BH/BH-NS merging: what could be a model EM-emission?

4. Searching for quasi-periodic transient events
As a part of time series investigation we developed a code for continuous search QPO-like events localized in time.
We apply the code to SPI-ACS/INTEGRAL …

5. SPI-ACS/INTEGRAL GW 150914 wavelet (Morlet) intermittency scalogram

6. Power Density Spectrum P = 7.1 s

7. SPI-ACS time profile P=7.1 s
GW150914

8. SPI-ACS/INTEGRAL GW 150914-QPO wavelet (Morlet) intermittency scalogram

9. Chance probability?
1x10-5 – 2x10-4, depending on the estimating procedure

10. GBM/Fermi scalogram?
No significant feature analogous to GW QPO is detected in GRB/Fermi data at the time of GW GBM

11. GRB/Fermi GW 150914-GBM (Connaughton+, 2016)

12. GW 150914-GBM A typical short GRB? Should be detected by SPI-ACS?
GW GBM may be detected by SPI-ACS at ~5σ based on our statistical comparison (cf. 15σ deduced by Savchenko+, 2016)

13. Statistical SPI-ACS and GBM/Fermi sensitivity comparison
SPI-ACS short GRBs sample
Short GRBs of GBM catalog
LogN – LogS normalization assuming parent population is the same for both experiment

14. Statistical SPI-ACS and GBM/Fermi sensitivity comparison

15. Statistical SPI-ACS and GBM/Fermi sensitivity comparison
5 sigma

16. SPI-ACS/INTEGRAL sky map
Localization of GW GBM (Connaughton+, 2016)

17. How to evenly reconcile GBM/Fermi and SPI-ACS observations? (0)
Let us suggest that GW GBM and GW ACS/QPO are real astrophysical events

18. How to evenly reconcile GBM/Fermi and SPI-ACS observations? (I)
GW GBM and GW ACS/QPO have a different nature
GW GBM is a usual short GRB occulted by the Earth for SPI-ACS FOV and not related to GW150914
Actual position of GW EM counterpart (which registered as ACS/QPO) is occulted by the Earth for GBM/Fermi
Complicated? But not impossible

19. BH-NS merging: what could be a model of EM-emission?
BH-NS merging => short gamma-ray burst
prompt gamma-ray emission (i.e. GRB)
extended gamma-ray emission
afterglow
kilonova (AKA macronova)

20. BH-BH merging
There is not sufficient matter after BH-BH merging for both disk accretion/jet launch and emission
A lot of models are proposed
Charged BHs
Magnetic reconnection
Third body (AGN disk, cool “dead” disk, triple system, …)

21. What might be the nature of SPI-ACS event? Possible scenario
Virtual triple compact system = collision of single BH with close BH-WD binary, formation of BH binary and prompt tidal disruption of WD can form massive and compact accretion disc around close BH binary

22. Possible scenario(virtual triple system)

23. Possible scenario
Virtual triple compact system = collision of single BH with close BH-WD binary, formation of BH binary and prompt tidal disruption of WD formed massive and compact accretion disc around close BH binary
BH-BH merging
Accretion onto resulting BH
No prompt emission (usually attributed to neutrino annihilation)
Extended Emission of short GRB due to BZ-jet launched

24. Summary
We detect in SPI-ACS data QPO-like gamma-ray emission coincident with BH-BH merging of GW150914
This emission has different signature (duration, QPO-type) than event GW GBM detected by Fermi
We do not claim that this event is certainly associated with GW (however, chance probability of cf for GW GBM)
If associated we could propose one of possible scenario of such emission as virtual triple system

25. Thank you
Questions are welcome!

26. Additional slides

27. What counterpart we could expect?
BH/NS, NS/NS
Short GRB (gamma) ~ 2 s
Extended emission of short GRB (gamma+X-ray) ~100 s
Afterglow (X-ray, optic, radio) ~ days
Kilonova (IR, optic) ~ 1-2 days

28. How to evenly reconcile GBM/Fermi and SPI-ACS observations? (II)
GW GBM and GW ACS/QPO have the same nature
GW GBM is a short GRB related to GW150914
GW ACS/QPO is an extended emission sometime observed after short GRBs
For some reasons GBM/Fermi not detected GW ACS/QPO and SPI-ACS not detected GW GBM
Actual position of GW EM counterpart is significantly restricted by small region of the LIGO localization error box

29. Morlet wavelet
The wavelet is defined as plane wave and then localised by a Gaussian window with proper normalization

30. SPI-ACS and GBM/Fermi sensitivity comparison
5 sigma

31. LIGO GW150914, GW151226, LVT151012
Abbott+, 2016