Scientists trace cosmic rays to massive black holes

Black hole

Above: (artist conception) Astronomers have discovered the biggest black hole orbiting a star 1.8 million light-years from Earth in the constellation Cassiopeia, with a record-setting mass of 24 to 33 times that of our Sun.

Henrik Svensmark is probably pleased to know where there source of cosmic rays is. Knowing that may help him hone his theory of cosmic rays and earths cloudiness being modulated by solar magnetic and solar wind activity. Here is the link to NASA’s press release. Maybe they’ll throw a party for this one too 😉 see post below.

From the LA Times:

By John Johnson Jr., Los Angeles Times Staff Writer

November 9, 2007

An international team of scientists said Thursday that they have tracked down the origin of the mysterious “Oh-My-God” particle — a cosmic ray bearing energies millions of times larger than the most powerful particle accelerator can produce on Earth.

Researchers at the Pierre Auger Observatory, a complex of detectors spread over a Rhode Island-sized slice of the South American prairie, said the most likely source for these ultra-high-energy particles is a type of black hole found at the center of some galaxies.

These violent phenomena are called active galactic nuclei because they both gobble up energy from the surrounding space and spit some out with tremendous force.

“This is a fundamental discovery. We have taken a big step forward in solving the mystery of the nature and origin of the highest-energy cosmic rays,” said Nobel laureate James Cronin, a professor emeritus at the University of Chicago and coauthor of the paper published in the current issue of the journal Science.

Cosmic rays are charged particles that can strike with the force of a thrown baseball. Fortunately for humans, Earth’s atmosphere serves as a shield, preventing the particles from reaching the surface.

The origin of cosmic rays, particularly the high-energy ones, has been a mystery since their discovery in 1938 by French scientist Pierre Auger. Scientists have only been able to speculate over what tumultuous processes could accelerate particles to energy levels 100 million times more powerful than anything produced at Fermi National Accelerator Laboratory in Illinois, Earth’s most powerful accelerator.

One of the chief candidates was black holes at the center of many galaxies, mainly because these are some of the most energetic objects in the universe.

But tracking the source of the particles has been difficult, in part because of their rarity. Each century, only one of the highest-energy particles — sometimes called Oh-My-God particles — strikes the atmosphere over any particular spot on Earth.

To research them, “You either need very long-lived scientists or an instrument covering a very large area,” said Henry Glass, a Fermilab particle physicist and a coauthor of the paper.

Besides being large, the detector had to be sophisticated enough to spot the cascade of billions of secondary particles that rain down when a high-energy cosmic ray hits the upper atmosphere.

That was the thinking behind the $54-million Auger Observatory, a collaboration of 17 nations and 370 scientists. The facility covers 1,200 square miles of Argentina’s Pampa Amarilla, or yellow prairie.

To trace the course of the secondary particles, known as extensive air showers, the observatory employs two types of detectors. One is made up of scores of ultra-pure-water tanks that register the energy and path of arriving secondary particles. The second is a set of telescopes spread around the observatory to spot the ultraviolet fluorescence that occurs when a high-energy particle hits the nitrogen in the upper atmosphere.

“What we’re doing is using the atmosphere as an amplifier,” Glass said.

The Auger detectors went to work nearly four years ago, even before construction was complete.

So far, Glass said, the detectors have tracked 27 high-energy cosmic ray events. At least 20 led back to previously known active galactic nuclei.

Two of the high-energy events were traced to a single galaxy, Centaurus A — also known as the Hamburger Galaxy — about 13.7 million light-years away.

Active galactic nuclei make up only about 1% of all galactic black holes. New ones are made when galaxies collide. The black holes spring to life, gobbling up pieces of the other galaxy.

Tracking the high-energy rays is just the first stage in the new field of cosmic ray astronomy, said Cronin, who conceived the Auger Observatory.

“In the next few years, our data will permit us to identify the exact sources of these cosmic rays and how they accelerate these particles,” he said.

Scientists also hope to open a similar observatory in the Northern Hemisphere. A site in Colorado has already been selected, Glass said.

“We are opening a new window in astronomy,” said Joao de Mello Neto, an astronomer at the University of Rio de Janeiro in Brazil and a coauthor of the paper.

Advertisements

4 thoughts on “Scientists trace cosmic rays to massive black holes

  1. Anthony,
    Awesome graphic. I will be posting a link from Dalton Minimum Returns. I wonder if some of our ice ages are from some excess cosmic rays when we get burst of cosmic rays when a black hole swallows a solar system, or another galaxy and we get sprayed with the cosmic splash.

  2. There was another recent article on large variations of high-energy cosmic rays (TeV) with a period of 62 Million years that may explain large swings in biodiversity. A (free) summary was published in the October, 2007 issue of Physics Today. The link is at-
    http://ptonline.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTOAD000060000010000018000001&idtype=cvips
    “Varying Cosmic-Ray Flux may explain cycles of biodiversity,” by Medvedev and Melott.
    Some excerpts:
    “The upshot of the nonlinear diffusion simulation is that the extragalactic cosmic-ray flux increases by almost a factor of five- not just 5%- as the solar system migrates from its southern to its northern extreme.”
    “The authors also point out that ionization of the atmosphere by cosmic rays can affect climate, electrical storm activity and atmospheric chemistry: There’s good evidence that ionization facilitates cloud formation, which in turn increases the planet’s albedo.”

  3. I forget exactly who it was that published on it (Nir Shaviv perhaps?) but somebody had used BE10 isotope analysis to suggest that trips through the spiral arms of the galaxy greatly increased the cosmic ray flux to Earth and corresponded very well with large episodes of glaciation.

  4. This post is just for clarification Anthony. The particles observed by the Auger detector are of the Extremely High Energy (EHE) type and are very rare with the rate of around one of these particles hitting an area of one square kilometer about once a year. Most garden variety cosmic rays that are posited to affect the Earth’s climate are partially solar and partially galactic in origin and not not extragalactic.
    The Sun is known to emit so-called low energy cosmic rays, and they are carried off in the solar wind. In addition, while the solar magnetic field varies in strength, other cosmic rays in our galaxy leak into our solar system. The amount that does depends on the varying strength of the solar field. This solar modulation is well measured and well-understood. The Auger-detected cosmic rays are of high enough energy that the sun’s and the galaxy’s magnetic field do not bend the path of these (charged) particles, and so they point back to whence they came.
    The Auger result, if it stands with more statistics, is a remarkable one. The origin of these EHE cosmic rays has been an ongoing research project for over 40 years now and is clouded by the fact that they come from all directions. That the very highest (and rarest) ones come from a preferred direction is a great discovery.

Comments are closed.