Transcript Rossi X-Ray Timing Explorer

Rossi X-Ray Timing
Explorer
Michael Vu
ASTR 403
There is more
to the
Universe than
meets the
eye!
X-Ray Science
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For medical use, doctors tune their X-ray machines so that your
bones absorb more X-rays than your skin.
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Stars emit the X-rays and are collected with satellite detectors
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An X-ray photon has an energy around 1000 times greater than
an optical photon, so the temperatures needed to produce X-rays
are up in the millions of degrees
Objects RXTE Observes
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binary star systems
accretion disk
black hole
neutron star
X-ray pulsar
RXTE
● The Rossi X-ray Timing Explorer (RXTE) is named after
Bruno Rossi, discoverer of the first non-solar source of
X-rays (Scorpius X-1).
● Launched on December 30, 1995
● Low-Earth orbit - 570 km
● It takes RXTE about 90 minutes to orbit the Earth once
● Its instruments generate spectra and light curves, but
not images
Light Curves
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A light curve is a graph of light intensity as a function of time. The
light is usually in a particular frequency interval or band.
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Counting the number of X-rays being emitted by a star every second
for an hour, you could generate a light curve from your observations.
Your light curve would tell you how bright your source is and the
amount of time it remained at that brightness.
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Light curves can be periodic
Light Curves
The sudden accretion of gas
from a low-mass star onto a
companion object leads to a
huge outpouring of relatively
soft X-ray emission
RXTE Spacecraft
Satellite Parts
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Solar Panels- Electricity is needed for the instruments and to enable
the spacecraft directional control
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High Gain Antenna- Commands sent as radio waves to rotate
satellite to position instruments in the direction we want them to see
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Star Trackers - help satellites align themselves in the right direction
to acquire sources
Satellite Parts
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RXTE has three different
scientific instruments on it
that observe slightly
different energy ranges
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Proportional Counter Array
(PCA) - five xenon gas
detectors that measure
X-rays in the 2-60 keV range
and can measure short-term
resolution
Satellite Parts
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High Energy X-ray Timing
Experiment (HEXTE) - eight
sodium-iodide crystal
detectors that are gathered
into two clusters, each
containing 4 scintillation
detectors that measure X-rays
in the 10-200 keV range and
the time resolution is in
microseconds.
Satellite Parts
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All-Sky Monitor (ASM) - three
cameras that are mounted on
a boom off the end of the
spacecraft. Inside each
camera is a proportional
camera sensitive to energies
in the 2-10 keV range.
Satellite Parts
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All-Sky Monitor (ASM) –
The shadow cameras uses slit
masks to produce shadow
patterns on a detector that is
filled with Xenon.
The patterns of different sources
are superposed to determine
intensity and direction of an
individual source.
ASM scans 80% of the sky every
90 minutes and is used to
measure long-term variability
of bright x-ray sources.
X-rays Light the Way to
Black Holes
X-rays Light the Way to
Black Holes
Black hole Light Curve
RXTE Discoveries
 Black Hole Sheds Accretion Disk
The system behaves like the celestial version of Old Faithful," notes Dr.
Craig Markwardt, a researcher working at Goddard Space Flight
Center. "At fairly regular intervals, the accretion disk is disrupted and
a fast moving jet is produced."
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Quasi-Periodic Oscillations (QPOs)
http://heasarc.gsfc.nasa.gov/docs/
xte/learning_center/discovery_arc
hive.html
Bibliography
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http://heasarc.gsfc.nasa.gov/docs/xte/learnin
g_center/
http://www.astrocappella.com/background/he
g_background.shtml
http://imagine.gsfc.nasa.gov/
SCIENTIST PARTY INVITATIONS
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Top scientists were invited to a party, and this is
how they replied:
Ampere was worried he wasn't current.
Audobon said he'd have to wing it.
Boyle said he was under too much pressure.
Mendel said he'd put some things together and see what
came out.
Darwin waited to see what evolved.
Newton planned to drop in.
Edison thought it would be illuminating.
Ohm resisted the idea.
Einstein thought it would be relatively easy to
attend.
Pavlov was drooling at the thought.
Gauss was asked to attend because of his
magnetic personality.
Pierre and Marie Curie were radiating enthusiasm.
Hawking tried to string enough time together to
make space in his
schedule.
Volta was electrified, and Archimedes buoyant at the
thought.
Heisenberg was uncertain that he could make it.
Watt reckoned it would be a good way to let off steam.
Hertz said in the future he planned to attend with
greater frequency.