NASA: Swift Finds 'Smoking Gun' of Black Hole Activation

[bystander]

Swift Finds 'Smoking Gun' of Black Hole Activation
NASA GSFC Swift 10-119 - 26 May 2010

Data from an ongoing survey by NASA's Swift satellite have helped astronomers solve a decades-long mystery about why a small percentage of black holes emit vast amounts of energy.

Only about one percent of supermassive black holes exhibit this behavior. The new findings confirm that black holes "light up" when galaxies collide, and the data may offer insight into the future behavior of the black hole in our own Milky Way galaxy. The study will appear in the June 20 issue of The Astrophysical Journal Letters.

The intense emission from galaxy centers, or nuclei, arises near a supermassive black hole containing between a million and a billion times the sun's mass. Giving off as much as 10 billion times the sun's energy, some of these active galactic nuclei (AGN) are the most luminous objects in the universe. They include quasars and blazars.
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Until Swift's hard X-ray survey, astronomers never could be sure they had counted the majority of the AGN. Thick clouds of dust and gas surround the black hole in an active galaxy, which can block ultraviolet, optical and low-energy, or soft X-ray, light. Infrared radiation from warm dust near the black hole can pass through the material, but it can be confused with emissions from the galaxy's star-forming regions. Hard X-rays can help scientists directly detect the energetic black hole.

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The optical counterparts of many active galactic nuclei (circled) detected by the Swift BAT Hard X-ray Survey clearly show galaxies in the process of merging. These images, taken with the 2.1-meter telescope at Kitt Peak National Observatory in Arizona, show galaxy shapes that are either physically intertwined or distorted by the gravity of nearby neighbors. These AGN were known prior to the Swift survey, but Swift has found dozens of new ones in more distant galaxies. Credit: NASA/Swift/NOAO/Michael Koss and Richard Mushotzky (Univ. of Maryland)

Swift Black Hole Survey Media Telecon Visuals
Goddard Multimedia Page

[Beyond]

It would seem as though contacting Galaxies are much similar to the weather systems here on Earth.
Here on the East Coast we have a lot of merging storms that gain strenght by two low pressure systems coming together just off the coast and heading Northeast up the coast. These storms are then fondly called "Nor'easters", They can be real "gullywhumpers" in warmer weather and Nasty Blizzards when its wintertime.
I've always wondered just how two low pressure areas combined. How does one low pressure area (usually the weakest one over land) just disappear and then re-appear in another low pressure area (you can tell because the second low pressure area is suddenly stronger).
So it looks like black holes do the same thing when Galaxies come in contact with one another. So how then is it possible for one Black Hole to just disappear and then reappear in the other Black Hole?? Perhaps the people who study Black Holes should also study low pressure areas here on Earth.

And speaking of Black holes; If truely there is an equal and opposite reaction for everything, then somewhere, there should be a lot of "White Holes" that for some reason have not been discovered yet. But then maybe thats a topic for another day?

All this heavy thinking !! Time for a root , or two.

[ta152h0]

wonder if black holes, being a singularity, are similar to lagrange points, the center of gravitational pulls, on a massive scale.

[bystander]

Massive Black holes "switch on" due to galaxy collision
Max Plank Institute for Extraterrestrial Physics | 14 June 2010

Researchers find reason for active galactic nuclei


The centre of most galaxies harbours a massive Black Hole. So does our Milky Way - the exotic object there however is pretty calm, unlike some supermassive gravity monsters in other galaxies. Scientists at the Max Planck Institute for Extraterrestrial Physics and other institutions around the world have now analysed 199 of these galaxies and discovered what makes the black holes at the galaxy centre become active: The black holes switched on some 700 million years ago after major galaxy merger events. (The Astrophysical Journal, in press)

Galaxy mergers - here shown is the system NGC 2207 in the constellation Canis Major - are the most likely reason why active galactic nuclei occur. Credit: ESO

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While in our own galaxy, the Milky Way, the central black hole was measured to have about 4 million solar masses, the 199 galaxies analysed now host black holes with a typical mass of about 300 million solar masses. These galaxies are much larger than our Milky Way and they are "active", which means that the inner region of the galaxy has a much higher luminosity than normal.

Astronomers believe that this radiation is powered by the accretion of matter on the super-massive black hole. Previous studies suggest that the formation and evolution of the host galaxies and their black holes are closely connected. However, there are various possibilities how the interstellar gas can be funnelled towards the black hole, and it is unclear which of these mechanisms is dominant at what stage in the evolution of a galaxy.

The two main mechanisms discussed are either internal disruptions, such as galaxy disk instabilities, or mergers and tidal interactions between close pairs of galaxies. Simulations of these scenarios lead to different predictions about the clustering of active galaxies and the masses of the host galaxies. Previous studies have analysed active galaxies selected by their optical or soft X-ray emission, which misses a major part of the radiation powered by the black hole accretion due to absorption and other effects.

"For our sample we used galaxies selected by their hard X-ray emission in the Swift-BAT all-sky survey, which provides an unprecedented depth and characterizations of source properties," says Nico Cappelluti from the Max Planck Institute for Extraterrestrial Physics, the lead author of the study. "With this survey we have a complete sample of local active galaxies - and so we can perform the measurement of black holes and the dark matter halos which host them in our 'cosmological backyard'," adds Marco Ajello, co-author from the Kavli Institute of Particle Astrophysics and Cosmology in Stanford, USA.

The clustering analysis of the 199 galaxies thus selected now for the first time gives an unbiased picture of the coexistence and evolution of galaxies and their active nuclei in the local universe. The scientists estimate that the black holes powering the active galaxies have a typical mass of about 300 million solar masses and are hosted by massive galaxies with about 200 billion solar masses residing in big bubbles of Dark Matter as massive as 100 Milky Ways. These properties scale with luminosity, i.e. the more luminous sources are hosted in more massive galaxies with bigger black holes.

By merging the observational evidence and theoretical model predictions, the scientists found that the most plausible scenario for the history of local active galaxies is a merger event: "The active galactic nuclei 'switch on' after a major merger event about 700 million years ago and shine brightly for the first part of their lives where they gain most of their mass," explains Cappelluti. "After about 200 to 500 million years they accrete with lower and lower efficiency as the gas reservoirs become depleted. Today, they have grown to super-massive black holes with 100 to 1000 million solar masses and shine with moderately low luminosity compared to other active galaxies." The black holes "starve" as their gas supply becomes less and less.

These results, which will be published in the renowned Astrophysical Journal, give an important contribution to our understanding of the origin of supermassive Black Holes shining in the centres of galaxies that have been puzzling astronomers for almost one century. In the coming years the new generation X-ray telescopes, such as eROSITA which is currently under construction at the Max Planck Institute for Extraterrestrial Physics, will perform further mappings of Black Holes and Dark Matter. These new studies will open up new perspectives on the history of the most exotic phenomena in the Universe.

AGN clustering in the local Universe: an unbiased picture from Swift-BAT

• lanl.arXiv.org > astro-ph > arXiv:1005.4968 > 27 May 2010
  The Astrophysical Journal, 2010, accepted for publication

[bystander]

Galaxy encounter fires up quasar
Royal Astronomical Society | RAS PN 10/47 | 24 June 2010

Using two of the world’s largest telescopes, an international team of astronomers have found evidence of a collision between galaxies driving intense activity in a highly luminous quasar. The scientists, led by Montserrat Villar Martin of the Instituto de Astrofisica de Andalucía-CSIC in Spain, used the Very Large Telescope (VLT) in Chile and the Gran Telescopio Canarias (GTC) on La Palma in the Canary Islands, to study activity from the quasar SDSS J0123+00. They publish their work in a paper in the journal Monthly Notices of the Royal Astronomical Society.

Several types of galaxies, known as active galaxies, emit enormous amounts of energy from their central region or nucleus, with the most luminous objects known as quasars. Most scientists argue that quasars contain a central black hole, with a mass of at least several million Suns.

The intense gravitational field created by the black hole drags material inexorably inwards. Before falling in, this material settles in an accretion disk where it becomes very hot and emits large amounts of energy responsible for most of the brightness of the quasar. Around the central quasar ‘engine’ is a torus (thick ring) opaque to the visible light emitted by the accretion disk. From a terrestrial perspective, if the torus is face-on then the radiation from the disk can be seen and the system is designated type 1, whereas in type 2 quasars the torus is edge-on and the radiation is concealed.

VLT and GTC observations of SDSS J0123+00: a type 2 quasar triggered in a galaxy encounter?

• es.arXiv.org > astro-ph > arXiv:1006.1517 > 08 Jun 2010