The Cosmic X-Ray Background
Early on,
x-ray satellites revealed a surprising
cosmic background glow
of x-rays and astronomers have struggled
to understand its origin.
Now, peering through
a hole in the obscuring gas and dust of
our own Milky Way Galaxy, the powerful orbiting
XMM-Newton telescope
has recorded this deep image of
the x-ray sky, resolving some of the
mysterious background
into many faint individual sources.
The tantalizing image
is color-coded, with red representing
relatively low energy x-rays, photons with 500 or so times the
energy of visible light.
Green and blue colors correspond to increasingly energetic
x-rays with up to about 10,000 times visible light energies.
Notably, the faint sources tend to be green and blue,
showing x-ray characteristics of huge amounts of material
falling into massive black holes in very distant galaxies.
Do massive black holes reside in the
hearts of all large galaxies?
The XMM-Newton
results add
to the growing consensus that they
do and that, from across the
universe,
x-rays produced as matter
feeds these black holes
account for
the cosmic x-ray background.