Black Hole mergers and electromagnetic signals

binary black hole mergers electromagnetic signals counterparts systemsIt seems that black hole theory suggests binary black hole mergers have no electromagnetic counterpart.

That is when you have 2 black holes spinning round each other very rapidly, getting closer together, colliding, merging, loss/conversion of energy, then forming a larger but less mass in total single black hole, then a 'ringdown' period, all in a fraction of a second - they do not produce a unique EM signal of itself.
binary black hole system mergers electromagnetic signals counterparts
This is perhaps due to the theory fact that no information can escape the event horizon of a black hole? Also, that 2 large black holes spinning rapidly around and closer to each other will clear all the material in their BBH system.

Living up to their name, black holes don't radiate any kind of light. However, many black holes can be "seen" because they are surrounded by material that is accelerated and heated by the black hole's gravity, causing the matter to emit light.

But two black holes with masses a few tens of times that of the sun are not expected to be surrounded by material as they circle around one another and eventually collide.
Gravitational Waves: Did Merging Black Holes Form from Single Star? | Space

Obviously any other space object going through that sort of energy event would produce a startling electromagnetic image.

Secondary EMF signals are associated with and linked to the events surrounding the binary black hole mergers. And of course the now famous LIGO Gravitational Wave.

Astrophysics and science suggest that the mergers of black holes do produce identifying electromagnetic (EM) emissions from surrounding materials and processes such as mechanics on gases in the black hole system etc.
bbh black holes mergers electromagnetic signals EMF
So any space event that astrophysics and science deems to be a double black hole merger will have all the associated EMF and other EM stuff (whatever you call it - electromagnetic waves, signals, frequencies, energies) linked to secondary sources and events.

The source of their creation may be the merging black holes but they are secondary signals and effects.
black holes
The above information is all new to me, so if anything has been described or understood incorrectly please let me know by commenting below or contacting the site.


  • Black hole mergers have no electromagnetic counterpart - no observable/detectable signal from inside the BHM
  • Any electromagnetic signals of a BBH are secondary processes but can but can be used to identify a binary black hole merger

Black hole mergers - no electromagnetic counterparts

black holes electromagnetic EM counterparts

Mergers of stellar-mass black holes (BHs), such as GW150914 observed by LIGO, are not expected to have electromagnetic counterparts.
Electromagnetic Counterparts to Black Hole Mergers Detected by LIGO

We shouldn’t have a prejudice that black hole binaries are always silent in terms of their electromagnetic signature.
LIGO’s black holes may have lived and died inside a huge star | New Scientist

The analysis of the gravitational wave signal indicates that it was produced by the coalescence of two black holes (Abbott et al. 2016). If at least one of the merging black holes was charged, following the Reissner-Nordstrom formula tion, up to 25% of the gravitational energy could have been converted into electromagnetic radiation (Zilh ̃ao et al.2012). However, it is expected that the charge of the black hole is spontaneously dissipated and is not significant for astrophysical applications. There is no theoretical work to date predicting electromagnetic emission from the coalescence of two non-charged back holes in vacuum. Indeed, it is not possible to create photons in a system with no matter outside of the gravitational horizon and only gravitational interaction involved, without invoking effects of quantum gravity, a theory which has not been developed, yet.
INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914 (direct link to PDF)

Binary black hole mergers - electromagnetic signatures

binary black holes electromagnetic signals detection

The inspiraling BH system will interact strongly - on a purely Newtonian level - with any surrounding material in the host galaxy

During the final moments of a binary black hole (BH) merger, the gravitational wave (GW) luminosity of the system is greater than the combined electromagnetic output of the entire observable universe. However, the extremely weak coupling between GWs and ordinary matter makes these waves very difficult to detect directly. Fortunately, the inspiraling BH system will interact strongly--on a purely Newtonian level--with any surrounding material in the host galaxy, and this matter can in turn produce unique electromagnetic (EM) signals detectable at Earth.
Electromagnetic Counterparts to Black Hole Mergers

2 two black holes merger electromagnetic signal counterpart

Time-variable EM signatures may be detectable

I will review several ideas that may be useful in identifying electromagnetic (EM) emission from supermassive black hole (SMBH) binaries, focusing on SMBHs expected to be detectable in gravitational waves by the future Laser Interferometric Space Antenna (LISA). In particular, any detectable EM emission is likely to be time-variable, which should aid in this identification. I will discuss four possibilities for such variable signals: (i) roughly periodic signatures due to the orbital motion prior to coalescence, (ii) a transient "precursor" caused by the gas trapped inside the binary's orbit, and a transient "afterglow" produced by (iii) post-merger gas accretion and (iv) by merger-induced shocks in the circumbinary disk. I will discuss whether these time-variable EM signatures may be detectable, and how they can help in identifying a unique counterpart, even with the relatively poor (fraction of a square degree) sky localization provided by LISA. I will also highlight the extra science that will be enabled if an EM counterpart is found, such as constraints on SMBH accretion physics, cosmology, and gravitational physics.
Electromagnetic Signatures of Supermassive Black Hole Mergers

black hole mergers electric universe theory

A consequence of shocks and accretion combined with the effect of relativistic beaming

Coincident detections of electromagnetic (EM) and gravitational wave (GW) signatures from coalescence events of supermassive black holes (SMBHs) are the next observational grand challenge ... We find that variable EM signatures correlated with GWs can arise in merging systems as a consequence of shocks and accretion combined with the effect of relativistic beaming. The most striking EM variability is observed for systems where spins are aligned with the orbital axis and where orbiting black holes form a stable set of density wakes, but all systems exhibit some characteristic signatures that can be utilized in searches for EM counterparts.
Relativistic Mergers of Supermassive Black Holes and their Electromagnetic Signatures

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Produces a powerful burst of gravitational radiation

The final merger of two massive black holes produces a powerful burst of gravitational radiation, emitting more energy than all the stars in the observable universe combined. The resulting gravitational waveforms will be easily detectable by the space-based LISA out to redshifts z > 10, revealing the masses and spins of the black holes to high precision. If the merging black holes have unequal masses, or asymmetric spins, the final black hole that forms can recoil with a velocity exceeding 1000 km/s. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced.
The Final Merger of Massive Black Holes: Recoils, Gravitational Waves, and Electromagnetic Signatures (direct link to PDF)

black hole electromagnetic waves frequencies amplitude

EM fields and Gravitomagnetic deformation of magnetic fields, anchored to the disc

A further intriguing possibility for such interaction is through EM fields and in particular through the gravitomagnetic deformation of magnetic fields, anchored to the disc, around the central region where the black holes inspiral and merge. As the black holes proceed in an ever shrinking orbit towards their ultimate coalescence, they will twist and stir the EM fields and thus affect their topology. Moreover, the spacetime dynamics might impact the fields in such a strong way as to generate EM energy fluxes which may reach and impact the disc and/or affect possible gas in the black holes’ vicinity. Last, but certainly not least, as the merger takes place the system could acquire (at least at much later times) a configuration where emissions through the Blandford-Znajek mechanism may take place.
Vacuum Electromagnetic Counterparts of Binary Black-Hole Mergers

black holes mergers electromagnetic counterpart signal binary

The kick will perturb the surrounding gas, and this can result in an electromagnetic signature

General Relativistic simulations show that the final coalescence of black hole binaries typically results in a kick or recoil of the merged black hole away from the center of mass of the pre-merger binary. The kick - which arises because gravitational waves carry away linear momentum - can have a magnitude of several thousands of km / s, although smaller values of the order of a few hundred km / s may be more typical. These kicks are of particular interest for supermassive black hole binaries that merge within gaseous disks. The kick will perturb the surrounding gas, and this can result in an electromagnetic signature of the merger process. Electromagnetic counterparts - if they exist - would be important for a variety of reasons, not least since they would allow localization of mergers that could otherwise be detected only via their gravitational wave emission.
Simulations of the effect of black hole recoil on surrounding gas disks | Joint Institute for Laboratory Astrophysics

black holes electromagnetic signals counterpart
Rapid changes in the accretion dynamics during binary coalescence may lead to bright observational signatures

The coalescing black holes may be surrounded by matter, in a form of spherically symmetric inflow or/and an accretion disk, which can form if the inflow possesses sufficient angular momentum. The accretion disk can have high density and large potential energy. Rapid changes in the accretion dynamics during binary coalescence may lead to bright observational signatures (Farris et al. 2012). Magnetic fields, anchored in the accretion disk, can cause bright radio emission simultaneous with the gravitational waves (M ̈osta et al.2010).

While supermassive black holes are often accompanied by substantial disks, black holes of stellar mass lose the disk created during the progenitor star collapse on a time scale of the order of
τdisk∼ 100 s (Woosley 1993). Sustainable accretion disks can be expected when a constant inflow of matter is provided by a companion star: in these cases, the black hole – star binary can be a bright and variable X-ray and gamma-ray source. However it remains to be established how likely it is to find a dynamically stable triple system composed of a binary black hole and an additional companion star.
INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914 (direct link to PDF)