Caused by a Stellar Explosion 26,000 Light Years Away?
Sound Crazy? Read Carefully Below.
(Originally posted February 20, 2005)
On December 26, 2004 a magnitude 9.3 earthquake occurred in the Indian Ocean off the coast of Sumatra in Malaysia. It caused a powerful tsunami which devastated coastal regions of many countries leaving over 240,000 people either dead or missing. It was the worst tsunami to affect this area since the 1883 explosion of Krakatao. The earthquake that produced it was so strong that it exceeded by a factor of 10 the next most powerful earthquake to occur anywhere in the past 25 years.
Indonesian 9.3 Richter earthquake:
It is then with some alarm that we learn that just 44.6 hours later gamma ray telescopes orbiting the Earth picked up the arrival of the brightest gamma ray burst ever recorded!
Gamma ray burst arrival:
This gamma ray blast was 100 times more intense than any burst that had been previously recorded, equaling the brightness of the full Moon, but radiating most of its energy at gamma ray wavelengths. Gamma ray counts spiked to a maximum in 1.5 seconds and then declined over a 5 minute period with 7.57 second pulsations. The blast temporarily changed the shape the Earth's ionosphere, distorting the transmission of long-wavelength radio signals. See stories on Space.com, BBC News, NY TImes.
Artists conception, courtesy of NASA
It was determined that the burst originated from the soft gamma ray repeater star, SGR 1806-20, a neutron star 20 kilometers in diameter which rotates once every 7.5 seconds, matching the GRB pulsation period. SGR 1806-20 is located about 10 degrees northeast of the Galactic center and about 20,000 to 32,000 light years from us, or about as far away as the Galactic center. (Originally, it had been thought to be 45,000 light years from us. but new results place it closer.) The outburst released more energy in a tenth of a second than the Sun emits in 100,000 years. Other gamma ray bursts have been detected whose explosions were intrinsically more powerful than this one at the source of the explosion, but since those explosions originated in other galaxies tens of thousands of times more distant, the bursts were not nearly as bright when they reached our solar system. What makes the December 27th gamma ray burst unique is that it is the first time that a burst this bright has been observed, one that also happens to originate from within our own Galaxy.
Astronomers have theorized that gamma ray bursts might travel in association with gravity wave bursts. In the course of their flight through space, gamma rays would be deflected by gravitational fields and would be scattered by dust and cosmic ray particles they encountered, so they would be expected to travel slightly slower than their associated gravity wave burst which would pass through space unimpeded. After a 45,000 year light-speed journey, a gamma ray burst arrival delay of 44.6 hours would not be unexpected. It amounts to a delay of just one part in 9 million. So if the gravity wave traveled at the speed of light (c), the gamma ray burst would have averaged a speed of 0.99999989 c, just 0.11 millionths slower. There is also the possibility that at the beginning of its journey the gravity wave may have had a superluminal speed; see textbox below.
Artist's conception, courtesy of NASA
The 9.3 Richter earthquake was ten times stronger than any other earthquake during the past 25 years, and was followed just 44.6 hours later on December 27th by a very intense gamma ray burst, which was 100 fold brighter than any other in the past 25 year history of gamma ray observation. It seems difficult to pass off the temporal proximity of these two Class I events as being just a matter of coincidence. A time period of 25 years compared to a time separation of 44.6 hours amounts to a time ratio of about 5000:1. For two such unique events to have such a close time proximity is highly improbable if they are not somehow related. But, as mentioned above, gravity waves would very likely be associated with gamma ray bursts, and they would be expected to precede them.
Many have inquired if there might be a connection between these two events (e.g., see the Space.com article). Not thinking of the gravity wave connection, astronomers have been reluctant to admit there might be a connection since they know of no mechanism by which gamma rays by themselves could trigger earthquakes. They admit that the December 27th gamma ray burst had slightly affected the ionization state of the Earth's atmosphere, but this by itself should not have caused earthquakes. However, if a longitudinal gravity potential wave pulse were to accompany a gamma ray burst, the mystery becomes resolved. The connection between earthquakes and gamma ray bursts now becomes plausible.
In his 1983 Ph.D. dissertation, Paul LaViolette called attention to terrestrial dangers of Galactic core explosions, pointing out that the arrival of the cosmic ray superwave they produced would be signaled by a high intensity gamma ray burst which would also generate EMP effects (e.g., see Page 3). He also noted that a strong gravity wave might be expected to travel forward at the forefront of this superwave and might be the first indication of a superwave's arrival. He pointed out that such gravity waves could induce substantial tidal forces on the Earth during their passage which could induce earthquakes and cause polar axis torquing effects.
In his book Earth Under Fire (as well as in his dissertation), LaViolette presents evidence showing that the superwave that passed through the solar system around 14,200 years ago had triggered supernova explosions as it swept through the Galaxy. Among these were the Vela and Crab supernova explosions whose explosion dates align with this superwave event horizon. He points out that these explosions could be explained if a gravity wave accompanied this superwave, it could have produced tidal forces which could have triggered unstable stars to explode as it passed through.
He wrote at a time when gamma ray bursts had just begun to be discovered, and when no one was concerned with them as potential terrestrial hazards. In recent years scientific opinion has come around to adopt LaViolette's concern, as can be seen in news articles discussing the SGR 1806-20 gamma ray outburst, e.g., see Space.com news story. They note that if this gamma ray burst had been as close as 10 light years it would have completely destroyed the ozone layer. By comparison, the Galactic superwaves LaViolette has postulated to have been generated as a result of an outburst of our Galaxy's core and to have impacted the Solar system during the last ice age would have impacted the solar system with a cosmic ray electron volley having an energy intensity 100 times greater than this hypothetical 10 light year distant stellar gamma ray burst. In comparision, SGR 1806-20 has been estimated to have a stellar progenitor mass of 150 solar masses, whereas our Galactic core has a mass of 2.6 million solar masses. In its present active phase, SGR 1806-20 is estimated to have a luminosity 40 million times that of the Sun, whereas during its active phase the Galactic center could reach luminosities of 400 trillion times that of the Sun. So it is understandable that if the Galactic center were to erupt, it would produce a gamma ray burst and a gravity wave far more intense than the outburst from this star.
the December 27, 2004 gamma ray burst shows us that we do not
live in a peaceful celestial environment. And if the December
26th earthquake was in fact part of this same celestial event,
we see that this stellar eruption has claimed many lives. For
this reason, it is important that we prepare for the possibility
of even stronger events in the future, the arrival of superwaves
issuing from the core of our Galaxy. Like the December
26th earthquake and the December 27th gamma ray burst, the next
superwave will arrive unexpectedly. It will take us by
It would have been possible to determine whether a Galactic gravity wave had indeed immediately preceded the December 26th earthquake by examining data from gravity wave telescopes. Since seismic waves from the Indonesian earthquake would have taken some time to propagate through the Earth to these gravity wave antenna, their signature could be distinguished from the gravity wave coming from SGR 1806-20. However, the major gravity wave telescopes were unfortunately not on line at that time. LIGO (Laser Interferometer Gravity Wave Observatory), which consists of two correlated telescopes, one in Washington state and one in Louisiana, each having a four kilometer long laser interferometer beam path, was in the process of being made operational and unfortunately was not collecting data at that time. We sent an email to the staff of the TAMA gravity wave antenna in Japan. Dr. Takahashi, who is responsible for the detector, replied that their telescope was unfortunately not operating during that week since they were making modifications at that time. So at present the gravity wave hypothesis remains neither confirmed nor disproven.
The December 27th GRB was not accompanied by any rise in the cosmic ray background, indicating that if it was accompanied by cosmic rays their intensity was unable to exceed the relatively constant extragalactic background flux arriving from distant galaxies. A Galactic superwave, on the other hand, would most likely produce a substantial rise in these levels.
Note that almost two months passed before the December 27th gamma ray burst found its way into news media stories. If unusually intense activity were to occur in the near future as the beginning stages of a superwave arrival, it is hoped that scientists will not keep this knowledge to themselves but rather allow the global news media to disseminate the story quickly to inform the world.