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Martin Elvis, Chandra X-ray Center
Chandra: Revolution through Resolution
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The Chandra X-ray Observatory
Launched 5 years ago 23 July 1999
revolutionized X-ray astronomy, and all of astronomy.
What is X-ray Astronomy?What is Chandra?
Why has Chandra done its job so well? And what exactly has Chandra done?
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When we look up at the night skywe see it filled with stars
But,
Outside the narrow range of colors
our eyes are sensitive to,
something quite different dominates
the night sky…
What is X-ray Astronomy?
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Powerful sources of X-raysPowerful sources of X-rays
A power source entirely different from
the nuclear fusion that drives the Sun and stars
…and much more efficient
Rosat All Sky Survey (MPE)X-ray map of the whole sky:
100,000 `sources’
X-ray Astronomy tries to find out what could cause such extraordinary power
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Compton gamma-ray Observatory
Chandra
Hubble
MMT
Sub-millimeter array
VLA
1015
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Whipple 10 meter
X-rays
Visible
X-ray Astronomy studies the short wavelength light from the Universe
1/1000
1/1000
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Compare Visible light and X-rays: “1000 times”
X-rays have: Wavelengths: 1/1000 visible light
0.1-6 nm (1-60A) vs. 500 nm (5000A)
Energies: 1000 x visible light “keV” instead of “eV” (electron volts) About 0.02 Joules/photon
Temperatures: 1000 times hotter 10 million degrees vs. 10 thousand
degrees for stars E=kT (k= Boltzman’s constant, 1.398e-9 J/K)
SNR G292.0+1.8 (Hughes et al.)
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What gets so hot? Surely not much can get so hot as a million degrees? Oh yes it can…
Sounds obscure but …
gravity power is the most common source of X-rays in the sky
Explosions: Supernovae and their remnants
Particles moving near the speed of light in magnetic fields
Matter falling into deep gravitational wells
Supernova 1987a Crab Nebula Abell 2029
Cluster of galaxies
Andromeda nearest galaxy¼ sun – centauri sun centauri
sun
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40 Years of X-ray Astronomy:1 billion times more sensitive
1962
1978
Good for 1 (one) Nobel Prize
good enough for my thesis
1999
Sco X-1: the brightest source of X-rays in the sky
NGC3783: a quasar appearing 10,000 times fainter than Sco X-1
2001Chandra
Distant galaxy 100,000 times fainter than NGC3783
Moon to scale
Resolution is the key
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X-ray astronomy took just 40 years to match 400 years of optical astronomy
1600 200018001700 1900
0.1”
1”
10”
100”
Galileo
Hubble Space Telescope
Dawn of History
Optical Astronomy
X-r
ay A
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Chandra
Year
Sha
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etai
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ecta
ble
Chandra takes X-ray Astronomy from its ‘Galileo’ era to its ‘Hubble’ era in a single leap
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What is Chandra?
Chandra is the greatest X-ray Observatory ever builtOrbits the Earth to be above the atmosphere (which absorbs X-rays, luckily!)
Goes 1/3 of the way to the Moon
every 64 hours (22/3 days)
Chandra takes superbly sharp images:
‘high resolution imaging’
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X-ray Telescopes are different
Chandra’s mirrors are almost cylinders
X-rays don’t reflect off a normal mirror – they get absorbed.
Only by striking a mirror at a glancing angle, about 1o,
do X-rays reflect.
Then they act like visible light
and can be focused
This makes for looooooooong telescopes
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Chandra is as big as a moving truck10 meters (32 ft) from mirror to detector, 1.2 meters (4ft) across mirror
…but focuses X-rays onto a spot only 0.025mm (1/1000 inch) across
That’s why Chandra is powerful
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Chandra detects individual photonsUses Wave-Particle Duality of Light
…but can disperse the incoming X-ray light: Light as Waves
CCD detectors count each X-ray individually
Delicate gold gratings diffract the light
each X-ray knocks free enough electrons to detect as a pulse of electricity
Light as particles
Chandra provides a great example of how
Quantum wave/particle duality
works in a real machine
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Chandra’s sharp focus revolutionizes our understanding
Best X-ray image of whole sky (ROSAT)
Best X-ray images before Chandra (ROSAT)
Chandra images
Earth observing satellite equivalents of …
SP
AC
E I
MA
GIN
G
Any sign of life? What’s this odd thing?
I get it!
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Like looking up the answers at the back of the book
Chandra has solved 20 year old mysteries in just one shot:
Yes – the background X-ray light is made up of contributions from millions of quasars
No – gas is not pouring down onto the galaxy at the center of a cluster of galaxies. Something stops it, but what?
Yes -- Our Milky Way sits in a bath of hot gas stretching to the Andromeda galaxy and beyond
Yes – quasars have hot winds blowing from their cores, at 2 million miles per hour
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…but also being given a whole new SAT test, without taking the class
Antennae – colliding galaxies
Nest of super-bright black holes in binaries – bigger than any star?
Centaurus A – nearest quasar
X-ray ‘smoke ring’ from explosion in core?
2 examples: What are we looking at?
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Chandra’s Revolution through Resolution continues…
Antennae: Deep Exposure
Chandra set to run for 5 more years
& may last much longer
Deeper looks show
•more and more detail,
•more and more surprises