MessageToEagle.com - Hiding behind clouds of dust, quasars are among the most energetic objects in the
universe, with some of them as luminous as ten thousand Milky Way galaxies.
Quasars are thought to have massive black holes at their cores, and astronomers also think that the regions
around the black holes actively accrete matter, a process that releases vast amounts of energy and
often ejects a powerful, narrow jet of material.
Quasars are so bright, that can be seen even when they are very far away.
This combination of being both highly energetic and located at cosmological distances makes them appealing
to astronomers trying to figure out the nature of galactic center black holes (our own Milky Way has one) and the conditions
in the early universe that prompt these monsters to form.
Quasars, and other galaxies with less dramatic but still active nuclei, come in a variety of subgroups.
Some, for example, contain hot gas moving at huge velocities, while others do not; some are seen with strong dust
absorption features, but others are not.
One problem in unraveling the mystery of quasars is that many (perhaps most)
quasar nuclei seem to be surrounded by a torus of obscuring dust that makes them difficult to study.
In fact, the standard model of these objects proposes that the various subgroups result from viewing the active
nuclei at different angles with respect to its dusty torus.
If the nucleus happens to be seen face-on, and
if there is a jet present, the gas velocities are large and the dust is not apparent; if seen edge-on through
the torus, the observed velocities are much smaller and the dust absorption features are dominant.
But so far no one knows for sure how quasars form, how they develop in time, or how (or what) physical
processes generate their stupendous energies.
The situation may be about to change. The violent activity around a black hole is very difficult to
analyze with just pen and paper, and so for years researchers have tried to use computer simulations
to identify what happens.
The data reveal a jet of high-energy particles that extends more than 100,000 light years from
the supermassive black hole powering the quasar. A new study shows for the first time that a
torus of gas and dust will naturally form around the nuclear black hole as material falls in
toward the nucleus. Credit: NASA/Chandra
But these simulations have faced a major challenge: tracing the detailed
flow of material from galaxy-wide scales of hundreds of thousands of light-years down into the central
tenth of a light-year around the black hole.
It has just been too hard to keep track of everything at such a fine scale across such a large one.
CfA astronomers Chris Hayward and Lars Hernquist, together with ex-CfA member Phil Hopkins and a
fourth colleague, have figured out a way to deal with the computational dilemma.
They use a clever scheme of multi-scale "zoom-ins" which allows them to track and model, in a physically
consistent way, selected parcels of gas as they move inward towards the torus.
Their simulations lead them to reach two very significant conclusions. First, they show that a dusty torus
is likely to be produced around the black hole - in the past it had been postulated in order to explain
the various morphologies but had never been demonstrated, even in a simulation.
Secondly, the scientists show that the torus is not just a passive screen: it plays an active role in
feeding gas and dust into the accretion disk around the black hole itself.
Abnormal Star Discovered In The 'Forbidden Zone'
A team of astrophysicists from Germany, France and Italy have discovered in the constellation Leo is an old star.
The star's existence raised at once many questions for scientists.
The object is definitely not as its "contemporaries" that appeared immediately after the Big Bang event.
Alcubierre Warp Drive - A Doomsday Weapon?
Is the Alcubierre warp drive a doomsday weapon or our passport to the Universe?
The Alcubierre warp drive is a theoretical tool that would allow for spacecraft to travel long distances in space rapidly,
by deforming the space-time continuum in a bubble around the spaceship...
Astronomical Mystery - Tremendous Explosion And Appearance Of Odd Rings
Twenty five years ago, on 1987 February 23, the brightest supernova of modern times was observed in the Large Magellanic Cloud.
The collision occurred at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow.
Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material...
Doesn't Secret Dark Matter Exist?
The more scientists study dark matter they know lesser and are not particularly optimistic about their results.
After completing this study, we know less about dark matter than we did before," said Matt Walker, of the Harvard-Smithsonian Center for Astrophysics.
A mysterious and still unknown substance is totally invisible in the Universe and reveals its presence only through its gravitational pull...
Dwarf Irregular Galaxy That Forces Scientists To Re-Evaluate Old Theory
Astronomers from Center for Astrophysics of the University of Porto, Portugal and Oskar Klein Centre, Stockholm University, Sweden come up
with new findings regarding one of the most studied objects - the dwarf galaxy I Zw 18.
The results led the scientists to the conclusion that this enigmatic blue compact dwarf might force
astronomers to review current galaxy formation models and much of what is known about galaxy formation and evolution might need substantial revision.
Violent Dragon Clash Billions Of Years Ago
NGC 5907 is sometimes called the "Splinter" or Knife Edge Galaxy because of its unusual appearance.
It is a spiral galaxy lying in the Dragon constellation,
about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.