CYGNUS X-3 CONFIRMED AS GALACTIC SOURCE OF HIGH ENERGY GAMMA RAYS - THIS STAR'S GREATER
SIGNIFICANCE TO US DOWN HERE

 

Picture of Cygnus X-3 taken from the Chandra X-ray
observatory(Pic credit: NASA-MSFC/SRON/MPE)

 

Andrew Collins reports on why the recent announcement that a deep space object is the source of high energy gamma rays is so important to our understanding human evolution, and the origins of the world's first sky-religions

 

Recently the prestigious journals Nature and Science announced that Cygnus X-3, either a black hole or neutron star located 30,000 light years away in the constellation of Cygnus, the celestial swan, has now been shown to produce periodic bursts of high energy gamma rays, the first confirmed source in the Milky Way galaxy (Tavani et al, Nature, 2009 & Fermi LAT Collaboration et al, Science, 2009. See also Reddy, 2009). This is a revelation, for extreme cosmic radiation of this type is normally only associated with extra-galactic objects such as quasars, powered by suspected super-massive black holes at the heart of distant galaxies (also known as AGNs, "active galactic nuclei"). Scientists now believe that monitoring Cygnus X-3, in its role as a microquasar, i.e. a smaller quasar inside our galaxy, might well lead to a better understanding of the production of gamma rays in quasars.

This announcement is, presumably, wonderful news for astrophysics, but why is it so important to the person in the street? Well, the answer lies in the fact that Cygnus X-3's production of high energy gamma rays is merely one facet of its extraordinary influence on the solar system, for it is known to spew out electromagnetic radiation across a broad spectrum of frequencies, from radio waves and infrared radiation to higher frequency X-rays and cosmic radiation. This is because Cygnus X-3 has additionally been proposed as the galaxy's first "microblazar", a galactic form of a so-called "blazar".

Cosmic Gun Barrel
So what exactly is a blazar? Electromagnetic radiation and cosmic particles across a whole range of frequencies are produced by black holes and neutron stars as they "accrete" gaseous matter, generally from close proximity stars, which they then use to create a highly energized ring of ionized gas that encircles the star around its equator, and is thought to be the source of the high energy gamma rays now being monitored from earth. This so-called accretion disk feeds the star, which every so often "powers up" by emitting unimaginable jets of plasma (ionized gas) that extend in opposite directions along the star's axis of rotation. These advance into the stellar medium for tens if not hundreds of light years in distance, accelerating cosmic particles close to the speed of light, and at the same time causing so many collisions inside the jets that the effects can be monitored down here on earth, usually as X-rays (bearing in mind that it takes 30,000 earth years for even light to reach us from Cygnus X-3, and thus any other slower waves or particles will take even longer to get here).

Incredible shot from the Hubble Space Telescope of a relativistic jet
produced by deep space object M87, a giant AGN (active galactic nucleus
powered by a super-massive black hole, in the Virgo constellation.
(Pic credit: NASA/Hubble with false coloring)


What makes a quasar into a blazar is the sheer fact that one of those twin jets is aligned near perfectly with our line of sight. Imagine looking down the end of a twelve-bore shot gun as one of its barrel is discharged. Having been expelled, the buckshot emerges as a tight cone that gradually expands and loses energy and momentum the further away it gets from the gun. Now consider that a blazar is like looking down the end of a vast cosmic gun barrel, which although many light years away, still sprays you with cosmic buckshot in the form of electromagnetic radiation and highly energy cosmic particles. Not enough to cause you or the planet any noticeable harm, but enough for this cosmic bombardment to be detected by scientific instrumentation. Blazers are likely to be super-massive black holes at the heart of distant galaxies. However, we now have one in our own neighbourhood, and this is Cygnus X-3, which although 30,000 light years away is actually quite close in astronomical terms (just to give you some idea of distance - from here to the centre of the Milky Way galaxy is 26,000 light years. Here astrophysicists suspect there is a super-massive black hole - labelled Sagittarius A - which has been in a dormant state for at least the last 20,000 years).

Cygnus X-3's role as a producer of high energy gamma rays, as well as its more controversial role as the galaxy's first microblazar (i.e. a local blazar), makes sense of something else we know about this strange star. It is one of the only known sources of cosmic rays, i.e. extremely high energy cosmic particles. These were first detected in the early 1980s by particle detectors in different parts of the world. At the time these facilities had just been switched on in the hope of detecting the decay of a sub-atomic particle known as the proton (see Cramer, 1985). Each was located underground, either in mountains (like the NUSEX facility in Mont Blanc, France) or deep inside mines (like the Soudan facility in Minnesota, USA). This was so that they shielded out any unwanted incoming cosmic radiation, which for the most part is unable to penetrate rock. Yet despite their best efforts, these proton detectors began detecting not the decay of the proton, but incoming cosmic particles from a single point source. They came in waves of precisely 4.8 hours (thus exactly five cycles a day), something that quickly revealed these particles' point of origin, for this was the time signature of Cygnus X-3, caused by the orbital motion of its suspected black hole or neutron star around its binary companion, a massive so-called Wolf-Rayet star, from which it steals gases, such as hydrogen and helium, in order to provide energy for its accretion disk.

Artists impression of Cygnus X-3, showing its compact star, either a black hole or neutron star, and its companion Wolf-Rayet star, from which it draws gas to feed its accretion disk and relativistic jets (Pic credit: Walter Feimer, NASA's Goddard Space Flight Center)

Cosmic Particles
What was so amazing about these incoming cosmic particles from Cygnus X-3 is that they were able to penetrate solid rock for a depth of hundreds of meters, before finally colliding with localized atoms to create secondary particles known as muons. No other type of cosmic ray was known to do this, causing scientists to assume, perhaps rightly, that these particles were unique to science, and perhaps even exotic in nature (i.e. they contradicted the standard model of physics).

These mysterious cosmic particles quickly gained the appellation "cygnons", although this was soon changed to the less potent, but equally revealing "cygnets", conjuring the vision of them being what Professor John G. Cramer of Washington University saw in 1985 in terms of "children of the swan" (Cramer, 1985), the swan being the Cygnus constellation's most popular identification in European star lore. Scientists will tell you that the existence of cygnets was never confirmed, so the evidence of their discovery at particle detectors such as NUSEX beneath Mont Blanc and Soudan in Minnesota has to be ignored; indeed, scientists who wrote papers on this subject were often ridiculed by their contemporaries. However, I can assure you that the cygnets from Cygnus never stopped coming, and that their detection has continued at facilities around the world, including the Soudan Mine in Minnesota (Allison et al, 1999).

Ancient Astronomies
Again, none of this should be of even the slightest interest to the person in the street. Even at a distance of 30,000 light years, Cygnus X-3 is so far away that why should we care? Well, perhaps you should care, for the attraction of the Cygnus constellation goes back to the earliest cave art. For instance, in 2000 German archaeoastronomer Dr Michael Rappenglück of Munich University identified the presence of the Cygnus constellation among abstract rock art in the deepest chamber of the famous Lascaux cave in southern France (Rappenglück, 2004). This was the setting for strange rites conducted by our Palaeolithic ancestors as much as 17,000 years ago.

It is also toward Cygnus, known more popularly as the Northern Cross, that religious buildings and structures have been aligned ever since the very first great stone complexes were erected in southeast Turkey around 12,000 years ago. On top of this, the Giza Pyramids, the Neolithic passage grave of Newgrange in Ireland, Hindu temples in India, Olmec centers in Mexico, native American mound sites in Ohio, and even a great stone circle in the shape of a boat in Sweden, all seem to reflect a strong interest in the Cygnus constellation (see Collins, 2006 & Collins, 2009).

Why is this? Why so much interest in this one constellation? The answer lies initially in the fact that some 17,000 years ago the stars of Cygnus occupied the position of the northern celestial pole. This is the pivot point of the heavens around which the heavens are seen to turn as viewed from anywhere in the northern hemisphere. Secondly, Cygnus is located on the Milky Way in the region of the so-called Cygnus Rift, where the starry stream divides into two separate rivers of stars due to a long dark area of stellar debris, once seen as the entrance to a primordial sky-world, or heaven, where life began, souls are created and the dead enter an afterlife among the stars (see Collins, The Cygnus Mystery, 2006).

Beyond all this was the obvious cruciform appearance of the star cluster, or asterism, invoking the image not just of a bird in flight, but also a celestial cross - one that in Christian times quickly became identified with the Cross of Calvary, the One True Cross, rediscovered on Golgotha Mount by the Empress Helena in the fourth century AD.

I See Cosmic Rays
Yet there might be another reason why Cygnus became so important to the ancient mindset, and this is the influence of cosmic rays on both the body and mind. As early as 1973 science writer and astronomer Carl Sagan proposed that cosmic rays reaching earth from some far off neutron star might well have been responsible for unexpected and quite sudden leaps in human evolution (Sagan, 1973). Normally, such changes are attributed to more mundane causes, such as diets, environmental factors, and even simple human necessity. However, a growing number of scientists are beginning to consider that cosmic rays might have played a role in human evolution, causing either mutations in DNA, or even the deletion of DNA sequences, which are then carried through to subsequent generations.

This is possible, yet even if it were true, pinning down the exact source of any incoming cosmic rays responsible for such mutations is problematic, as nearly all cosmic particles are positively charged, which means that they are deflected left, right and centre by intense magnetic fields, both out in the galaxy and inside the solar system. Only those particles that possess a neutral charge avoid being affected in this way, and so reach us directly from source. However, tracing their source via their trajectory has proved a tricky process, with no confirmed candidates to date. In fact, other than the cygnets arriving directly from Cygnus X-3 there are only a few other possible sources of cosmic rays inside our galaxy, the most likely being an X-ray binary star called Hercules X-1, located around 20,000 light years away.

It is reasonable to conclude that if cosmic rays do affect human evolution, then the cygnets of Cygnus X-3 have played some role in this process, particularly as it is suspected that this star has been in its current state of spontaneous, periodic activity for an estimated 700,000 years (Marti, 2005). This is when mankind's direct forerunners are known to have reached Britain. Although these so-called hominids (or hominins as the scientists like us to refer to them today) preceded the Neanderthals by as much as 500,000 years, they would appear to have been not unlike modern humans. As has been determined from a number of breathtaking discoveries in a thick clay layer dating back 700,000 years, exposed along a stretch of beach at Pakefield in Suffolk, these hominids used quite sophisticated hand tools made of flint (Kinver, 2005). Was it around this time that cosmic rays from Cygnus X-3 first began affecting human evolution?

Did cosmic rays affect the evolution of our earliest ancestors, like those hominids who inhabited what is today East Anglian in England around 700,000 years ago?
If so, did they come from Cygnus X-3?
(Pic credit: American Museum of Natural History)

One of the sophisticated flint tools left behind
by Pakefield man some 700,00 years ago.

It is plausible. Yet more important is attempting to unravel Cygnus's overall impact on humanity. Learn this and you will perhaps answer why the constellation became so important to our Palaeolithic ancestors, when humanity was still creating fabulous art in the caves of Western Europe. The key, I feel, is the simple fact that we can see cosmic rays. This was first realized on the Apollo space missions during the 1960s. When astronauts attempted to go to sleep, they began seeing flashes of light before their eyes. This occurred either with their eyes open or closed; it didn't matter which. In-flight experiments on subsequent missions determined that what the astronauts were experiencing were cosmic rays producing a burst of light as they decayed en route through the vitreous part of the eye.

This effect had not really been noticed before, simply because down here on earth the upper atmosphere shelters us from the brunt of cosmic radiation hitting the planet. Moreover, we are rarely in a pitch black environment in which it might be possible to witness a cosmic ray pass through our eyes. Yet it probably does occur, and more frequently that is realized, just ask a caver who spends long periods underground. They will tell you that they frequently witness unaccountable flashes of light that seem objective, but are in fact probably only occurring inside the head. I even found that miners who used to work in the Soudan iron mine in Minnesota, before it became the site of an underground particle detector, would occasionally see weird flashes of light in the total darkness. Were these, in fact, cosmic rays inbound from Cygnus X-3, like those registered by the Soudan facility in the 1980s? I'd like to think it was possible.

Primary cosmic particles hit the atmosphere where they collide with atoms of oxygen and nitrogen, breaking up to create showers of secondary particles. These then enter the lower atmosphere, colliding with even more atoms to create even weaker secondary particles. By the time these cascades of particles reach the ground, they are basically harmless; if they weren't then humanity might never have evolved in the first place. Only the most powerful cosmic primaries cause bigger problems, and of these only a very small percentage reach the surface of the planet. Among the cosmic particles that are able to reach the earth - in fact they pass right through it - are neutrinos, neutrally charged particles with an extremely low mass. They are produced during radioactive decay by stars, including, of course, our own sun. Since neutrinos are unaffected by the same electromagnetic processes that govern charged particles, they pass through the earth, and us, without interacting at all. The only other cosmic particles that are known to penetrate the earth to any depth are the cygnets from Cygnus X-3. Like neutrinos, they are neutrally charged, yet unlike neutrinos, they do interact with matter, and that includes us humans.

What all this means is that if you were hundreds of meters below the surface of the planet, deep inside a cave, and you witnessed a blue-white flash before your eyes, the chances are that this was in fact a cosmic ray. Yet since only a tiny percentage of cosmic rays penetrate the earth, there has to be a small chance that what you experienced was a particle inbound from Cygnus X-3, and this is important, for it tells us something about why Cygnus might have attracted the attention of our distant ancestors. For I can imagine that when experiences like this first started occurring deep inside caves, the observer might have considered that a flash of light under such circumstances had to mean something. If the person was a shaman, perhaps, in some kind of trance or altered state of consciousness, then it is plausible that the flash will have been seen as connected in some way with their activities. Maybe they saw this seeing of the light as in some manner enlightening. Just maybe the occurrence helped trigger other more profound visionary experiences concerning the nature of life and our place in the universe.

In time those who occupied the caves for religious purposes would, I sense, have realized, eventually, that the flashes were more frequent, or pronounced, when the Cygnus constellation was overhead, just as cygnets were found to be more easily detected when Cygnus was high in the sky. If so, then this might well have helped forge a spiritual link, not just with this particular cluster of stars, but also the area of the Milky Way to which they occupied, i.e. the Cygnus Rift. In time, a connection between the light triggering process underground and the Cygnus constellation would surely have led to cosmological myths featuring both the astronomical position of the asterism, and its abstract form as a bird (or indeed a cross), identified most usually as a swan or goose flying, wings outstretched, down the Milky Way. This avian form then became a symbol of divine knowledge and creative inspiration, explaining why perhaps the mythical song of the swan came to represent the divine source of inspiration for epic storytelling and poetry in Homeric tradition; Homer himself being referred to as the Maeonian Swan, or the Swan of Meander.

The first mortal poet in Greek Hellenic tradition was Orpheus, who was not only Homer's mythical ancestor, but also one of the identities of the swan of Cygnus in classical star lore. Orpheus was said to have been transformed into a swan and cast into the sky next to his beloved lyre - the constellation of Lyra - after his body was torn apart by the crazed female followers of the god Dionysius. In Pythagorean tradition the souls of great poets were said to have become swans. The soul of Apollo, the god of music and song, was thought to have been transformed in this manner.

The swan became a symbol of poetry and inspiration also in India, where in Hindu tradition it is the vehicle of the goddess Saraswati, the consort of the creator god Brahma. Indeed, it was Saraswati who is said to have alerted her husband to the sound of the cosmic swan-goose hamsa, enabling him to effect the creation of the physical universe. In Vedic star lore the stars of Cygnus were identified with the swan-goose hamsa (Collins, 2006).

Elsewhere in the world the bird of Cygnus was seen as the creator of the cosmic egg that subsequently broke or opened to become the physical universe, and everything within it. It is also likely that very similar cosmogonies, featuring birds that bring forth the physical world, were inspired by earlier traditions linking the stars of Cygnus with the idea of cosmic creation. Whether such conviction was either directly or indirectly influenced by visionary experiences, triggered by cosmic rays seen as flashes of light by Palaeolithic shamans deep inside caves, is debatable. However, at the root of many ancient cosmologies is, I believe, a profound connection with the Cygnus constellation, and confirmation that one of its stars, Cygnus X-3, produced bursts of high energy gamma rays has moved us closer to understanding its greater influence on both human evolution and the origins of the world's earliest sky-religions.

Further Reading
Allison et al, "Cygnus X-3 revisited: 10 years of muon and radio observations", Proceedings of the 26th International Cosmic Ray Conference (ICRC 99), Salt Lake City, Utah, 17-25 Aug 1999.
Collins, Andrew, Beneath the Pyramids, 4th Dimension Press, Virginia Beach, VA, 2009.
Collins, Andrew, The Cygnus Mystery, Watkins, London, 2006.
Cramer, John G., "Children of the Swan", Analog AV-12, 1985, at http://www.npl.washington.edu/AV/altvw12.html.
Fermi LAT Collaboration et al, "Modulated High-Energy Gamma-Ray Emission from the Microquasar Cygnus X-3" Science 326: 5959 (December 11, 2009), 1512-1516
Kinver, Mark, "Tools unlock secrets of early man" BBC News, December 14, 2005, at http://news.bbc.co.uk/1/hi/sci/tech/4526264.stm
Marti J., D Perez-Ramirez, J L Garrido, P Luque-Escamilla, J M Paredes, 'Possible Hot Spots Excited By The Relativistic Jets Of Cygnus X-3', Astronomy and Astrophysics 439 (August 2005), 279-285.
Rappenglück, Professor Michael, 'A Palaeolithic Planetarium Underground - The Cave of Lascaux Pt 1', Migration and Diffusion 5:18 (2004), 93-119.
Reddy, Francis, "Fermi Telescope Peers Deep into Microquasar", November 26, 2009, at NASAhttp://www.nasa.gov/mission_pages/GLAST/news/fermi-cygnus.html
Sagan, Carl, The Cosmic Connection, Anchor Press, New York, 1973.
Tavani, et al, "Extreme particle acceleration in the microquasar Cygnus X-3", Nature 462, 620-623 (3 December 2009). Available at http://arxiv.org/abs/0910.5344.