BLACK HOLE BLAZARS AND THE RELEASE OF NEARLY LIGHT SPEED JETS

FROM:  NASA
WASHINGTON -- Astronomers are actively hunting a class of supermassive
black holes throughout the universe called blazars thanks to data
collected by NASA's Wide-field Infrared Survey Explorer (WISE). The
mission has revealed more than 200 blazars and has the potential to
find thousands more.

Blazars are among the most energetic objects in the universe. They
consist of supermassive black holes actively "feeding," or pulling
matter onto them, at the cores of giant galaxies. As the matter is
dragged toward the supermassive hole, some of the energy is released
in the form of jets traveling at nearly the speed of light. Blazars
are unique because their jets are pointed directly at us.

"Blazars are extremely rare because it's not too often that a
supermassive black hole's jet happens to point towards Earth," said
Franceso Massaro of the Kavli Institute for Particle Astrophysics and
Cosmology near Palo Alto, Calif., and principal investigator of the
research, published in a series of papers in the Astrophysical
Journal. "We came up with a crazy idea to use WISE's infrared
observations, which are typically associated with lower-energy
phenomena, to spot high-energy blazars, and it worked better than we
hoped."

The findings ultimately will help researchers understand the extreme
physics behind super-fast jets and the evolution of supermassive
black holes in the early universe.

WISE surveyed the entire celestial sky in infrared light in 2010,
creating a catalog of hundreds of millions of objects of all types.
Its first batch of data was released to the larger astronomy
community in April 2011 and the full-sky data were released last
month.

Massaro and his team used the first batch of data, covering more than
one-half the sky, to test their idea that WISE could identify
blazars. Astronomers often use infrared data to look for the weak
heat signatures of cooler objects. Blazars are not cool; they are
scorching hot and glow with the highest-energy type of light, called
gamma rays. However, they also give off a specific infrared signature
when particles in their jets are accelerated to almost the speed of
light.

One of the reasons the team wants to find new blazars is to help
identify mysterious spots in the sky sizzling with high-energy gamma
rays, many of which are suspected to be blazars. NASA's Fermi mission
has identified hundreds of these spots, but other telescopes are
needed to narrow in on the source of the gamma rays.

Sifting through the early WISE catalog, the astronomers looked for the
infrared signatures of blazars at the locations of more than 300
gamma-ray sources that remain mysterious. The researchers were able
to show that a little more than half of the sources are most likely
blazars.

"This is a significant step toward unveiling the mystery of the many
bright gamma-ray sources that are still of unknown origin," said
Raffaele D'Abrusco, a co-author of the papers from Harvard
Smithsonian Center for Astrophysics in Cambridge, Mass. "WISE's
infrared vision is actually helping us understand what's happening in
the gamma-ray sky."

The team also used WISE images to identify more than 50 additional
blazar candidates and observed more than 1,000 previously discovered
blazars. According to Massaro, the new technique, when applied
directly to WISE's full-sky catalog, has the potential to uncover
thousands more.

"We had no idea when we were building WISE that it would turn out to
yield a blazar gold mine," said Peter Eisenhardt, WISE project
scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
Calif., who is not associated with the new studies. "That's the
beauty of an all-sky survey. You can explore the nature of just about
any phenomenon in the universe."  
                                                

                                                 Image of a Black Hole. Credit NASA 

JPL manages and operates WISE for NASA's Science Mission Directorate
in Washington. The principal investigator for WISE, Edward Wright, is
at UCLA. The mission was competitively selected under NASA's
Explorers Program, managed by the Goddard Space Flight Center in
Greenbelt, Md. The science instrument was built by the Space Dynamics
Laboratory in Logan, Utah, and the spacecraft was built by Ball

Aerospace & Technologies Corp. in Boulder, Colo. Science operations
and data processing and archiving take place at the Infrared
Processing and Analysis Center at the California Institute of
Technology (Caltech) in Pasadena. Caltech manages JPL for NASA.

MASSIVE BLACK HOLE SUCKS IN GAS FROM ANOTHER STAR

The above picture and following excerpt is from the NASA website:

This artist's impression shows a binary system containing a stellar-mass black hole called IGR J17091-3624, or IGR J17091 for short. The strong gravity of the black hole, on the left, is pulling gas away from a companion star on the right. This gas forms a disk of hot gas around the black hole, and the wind is driven off this disk. New observations with NASA's Chandra X-ray Observatory clocked the fastest wind ever seen blowing off a disk around this stellar-mass black hole. Stellar-mass black holes are born when extremely massive stars collapse and typically weigh between five and 10 times the mass of the Sun. The record-breaking wind is moving about twenty million miles per hour, or about three percent the speed of light. This is nearly ten times faster than had ever been seen from a stellar-mass black hole, and matches some of the fastest winds generated by supermassive black holes, objects millions or billions of times more massive. Another unanticipated finding is that the wind, which comes from a disk of gas surrounding the black hole, may be carrying away much more material than the black hole is capturing. The high speed for the wind was estimated from a spectrum made by Chandra in 2011. A spectrum shows how intense the X-rays are at different energies. Ions emit and absorb distinct features in spectra, which allow scientists to monitor them and their behavior. A Chandra spectrum of iron ions made two months earlier showed no evidence of the high-speed wind, meaning the wind likely turns on and off over time. Image Credit: NASA/CXC/M.Weiss

COLLAPSE OF MASSIVE STAR CREATES A STELLAR-MASS BLACK HOLE

The following excerpt is from the NASA website:

"On the left, an optical image from the Digitized Sky Survey shows Cygnus X-1, outlined in a red box. Cygnus X-1 is located near large active regions of star formation in the Milky Way, as seen in this image that spans some 700 light years across. An artist's illustration on the right depicts what astronomers think is happening within the Cygnus X-1 system. Cygnus X-1 is a so-called stellar-mass black hole, a class of black holes that comes from the collapse of a massive star. The black hole pulls material from a massive, blue companion star toward it. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being redirected away from the black hole in the form of powerful jets.

A trio of papers with data from radio, optical and X-ray telescopes, including NASA's Chandra X-ray Observatory, has revealed new details about the birth of this famous black hole that took place millions of years ago. Using X-ray data from Chandra, the Rossi X-ray Timing Explorer, and the Advanced Satellite for Cosmology and Astrophysics, scientists were able to determine the spin of Cygnus X-1 with unprecedented accuracy, showing that the black hole is spinning at very close to its maximum rate. Its event horizon -- the point of no return for material falling towards a black hole -- is spinning around more than 800 times a second.

Using optical observations of the companion star and its motion around its unseen companion, the team also made the most precise determination ever for the mass of Cygnus X-1, of 14.8 times the mass of the Sun. It was likely to have been almost this massive at birth, because of lack of time for it to grow appreciably."

GALATIC ENCOUNTERS MAY CAUSE GROWTH OF HUGE BLACK HOLES

The following excerpt is from the NASA website:

"Astronomers have used a large survey to test a prediction that close encounters between galaxies can trigger the rapid growth of supermassive black holes. Key to this work was Chandra's unique ability to pinpoint actively growing black holes through the X-rays they generate.

The researchers looked at 562 pairs of galaxies ranging in distances from about 3 billion to 8 billion light years from Earth. They found that the galaxies in the early stages of an encounter with another were more likely than isolated, or "lonelier" galaxies to have actively growing black holes in their cores.

These two composite images show a sample of the pairs of galaxies that are undergoing close encounters in the survey. In these images, the data from NASA's Chandra X-ray Observatory are shown in purple and Hubble Space Telescope data are in gold. In both images, the point-like X-ray source near the center is generated by gas that has been heated to millions of degrees as it falls toward a supermassive black hole located in the middle of its host galaxy. The other faint X-ray emission may be caused by hot gas associated with the pair of galaxies.

The authors of the study estimate that nearly one-fifth of all moderately active black holes are found in galaxies undergoing the early stages of an interaction. This leaves open the question of what events are responsible for fueling the remaining 80% of growing black holes. Some of these may involve the late stages of mergers between two galaxies. Less violent events such as gas falling in from the halo of the galaxy, or the disruption of small satellite galaxies are also likely to play an important role.

The survey used in this research is called the Cosmic Evolution Survey (COSMOS), which covers two square degrees on the sky with observations from several major space-based observatories including Chandra and Hubble. Accurate distance information about the galaxies was also derived from optical observations with the European Southern Observatory's Very Large Telescope. The researchers compared a sample of 562 galaxies in pairs with 2726 solo galaxies to come to their conclusions.

A paper describing this work has been accepted for publication in The Astrophysical Journal. The study was led by John Silverman from the Institute for the Physics and Mathematics of the Universe (IPMU) at the University of Tokyo in Japan. There are 54 co-authors from various institutions around the world.

Credits: X-ray: NASA/CXC/IPMU/J.Silverman et al; Optical: NASA/STScI/Caltech/N.Scoville et al."