Bill Steigerwald					March 24, 2003

NASA Goddard Space Flight Center, Greenbelt, Md.

301 286 5017


Release 03-33


<bold>NEW CLASS OF HOT-TEMPERED BLACK HOLES BUCKS TRENDS  


</bold>NASA scientists have found two smoking-gun features of an
intermediate-mass black hole that suggest these newly identified
objects are fundamentally different from other types of black holes,
running hotter than expected.   


The observation further establishes these objects as a new class of
black hole, yet offers a perplexing twist: Intermediate-mass black
holes do not appear to suck in matter the same way as their larger and
smaller cousins do.  


Drs. Tod Strohmayer and Richard Mushotzky of NASA Goddard Space Flight
Center in Greenbelt, Md., present these findings today at a press
conference at the meeting of the High Energy Astrophysics Division of
the American Astronomical Society at Mt. Tremblant, Quebec. The
observation was made with the European Space Agency's XMM-Newton
satellite and NASA's Rossi X-ray Timing Explorer.  


"We have been neatly assembling pieces of the black-hole puzzle over
the years," said Strohmayer. "Now we have new pieces, some of which are
familiar and others which don't seem to fit. A picture may emerge in
which intermediate-mass black holes are a different beast altogether."


Black holes are objects so dense and have a gravitational potential so
heightened that nothing, not even light, can escape the pull if it
ventures too close. Although the black holes themselves are invisible,
the region surrounding them glow furiously as matter pours in.  


Stellar black holes are the remains of massive stars that have
imploded, left with the mass of up to about ten suns. Supermassive
black holes contain the mass of millions to billions of suns confined
to a region about the size of our Solar System. Scientists suspect that
intermediate black holes contain the mass of about 500 to 10,000 suns.
Stellar and supermassive black holes exhibit similar features, only
scaled accordingly. Intermediate-mass black holes might buck this
trend, Strohmayer said.  


Scientists call intermediate-mass black holes ultra-luminous X-ray
sources (ULXs). While they are clearly extremely bright sources of
X-ray radiation, these objects could be smaller black holes with all of
their energy (or, light) beamed in our direction, like a flashlight
shined directly into the eyes. This would make them appear
intrinsically brighter (and more massive) than they really are.  


Strohmayer and Mushotzky's observation strongly rules out the beaming
model for one of the brightest ULXs in galaxy M82. The scientists
uncovered, for the first time, a type of flickering in this ULX's X
rays called quasiperiodic oscillations (QPOs). The oscillations likely
arise from gas whipping around the black hole in a tight and frenzied
orbit  the collective, periodic motion of material in what is known as
a black hole accretion disk. It is unlikely that light from an entire
accretion disk would be beamed, Strohmayer said.  


The scientists also detected the first "broad iron line" from a ULX.
This refers to a pattern of X-ray light from iron atoms stretched by
extreme gravity, a telltale sign of black hole shenanigans afoot, as
Einstein predicted. The one-two punch of a QPO and broad iron line
suggests that this ULX in M82 is a non-beamed black hole at least 50
times more massive than a stellar black hole.  


What the scientists cannot explain, however, is why the M82 ULX
accretion disk is so hot. Theory predicts that smaller black holes have
hotter accretion disks, particularly in the inner ring closest to the
black hole. This is because material can swirl faster and more closely
around a stellar size black hole compared to a supermassive black hole.
Yet, according to XMM-Newton data, the intermediate-sized black hole in
M82 has an accretion disk hotter than those found around stellar black
holes.  


"Something new and exotic may be taking place in this object to heat
the accretion disk to such high temperatures," said Strohmayer. "The
nature of these objects is one of the most interesting conundrums in
high energy astrophysics."  


XMM-Newton was launched from French Guiana in December 1999 and carries
three advanced X-ray telescopes. NASA Goddard hosts the XMM U.S. guest
visitor support center. NASA Goddard operates the Rossi Explorer, which
was launched in 1995.  


For animation, refer to the directory at:

<bold><underline><color><param>0000,0000,00FF</param>http://universe.gsfc.nasa.gov/press/ulx/


</color></underline></bold>-end-  


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