1. Gravitational wave sources
Tomek Bulik
University of Warsaw

2. Gravitational waves have been detected!
The source – and its properties
Astrophysical significance
Outlook for the future
Possible mechanisms of gamma ray production

3. The detection on Sep 14th, 2015

4. How does the merger look?

5. What is it?
A binary black hole!
How do we know it?

7. Where does it come from?
Binary evolution
Cluster origin

8. Evolutionary scenario
Credit: Wojtek Gładysz

9. Globular clusters Paths to BHS Escaping binaries (dominating)
Induced mergers inside GC
Mass distribution
BH production efficiency

10. BH production efficiency
Number of merging BBH binaries per 10^6 solar masses of stars.

11. Dependence on the cluster mass
Z=0.001 (5% Zsun)

12. The dominant contribution – escaping BHBH

13. A list of breakthroughs
Detection of gravitational waves
Detection of a black hole
Detection of black hole binary
Evidence for BHs with masses of 30 and and up to 60 solar masses
Possibility to test General Relativity
Possibility to test Quantum Gravity(?)
The brightest source ever seen in the sky:

14. What next
The detectors are being improved, and new detectors will be added to the network

15. Observing plans

16. Upcoming sensitivity

17. Expected event rates Rate estimate: In the final configuration:
Range increased 3x
Observations all year
Efficiency will increase with KAGRA, and LIGO- India
Rates can be as high as one per day

18. Can we have gamma rays from BHBH merger?
Fermi: a weak gamma ray burst 0.4 seconds after the GW detection
INTEGRAL – an upper limit, lower than the Fermi detection flux
A hint, but not significant enough to claim detection
Nevertheless it sparked a lot of ideas

19. Two BHs merging inside a star
Rapidly rotating star, core fragments, makes two BHs. Subsequent merger inside a star followed by a standard GRB. (Loeb, 2016)

20. A remnant disk.. The first BH carries a dormant disk
Before the merger the disk wakes up by tidal forces
A disk is ready to accrete onto a newly formed BH after merger

21. BH formation triggered by the 2nd BH
At the onset of a common envelope phase the tidal squeezing triggers formation of a BH inside a star.
BHs inspiral inside the star, and cause a GRB after merger

22. Two charged BHs Charged BH moving at relativistic speeds
Currents → magnetic fields → magnetopshere → particle acceleration → high energy radiation
Magnetic fields → reconnection → gama - rays

23. Exotica Charged BHs Megers of BHs with firewalls
Mergers of gravastars, boson stars, Q-stars...
Release of a large amount of energy, close to the GW luminosity

24. Do not forget about neutron stars
A fraction of the sources will contain neutron stars: NSNS and BHNS
These phenomena will be rare, but will certainly be sources of gamma rays
Triggers should be distributed very fast, less tan minute

25. Conclusions In the coming years GW sources will be plentiful
Locations of the most promising sources will be manageable – down to a few square degrees.
Search for EM counterparts of GW sources is a high risk - high reward activity.
Quantum gravity
Exotic models
Speed of gravity
Origin of GRBs
and many more I suppose