Rossi X-Ray Timing Explorer

Rossi X-Ray Timing

Explorer

Michael VuASTR 403

There is more to

the Universe

than meets the

eye!

X-Ray Science

For medical use, doctors tune their X-ray machines so that your bones absorb more X-rays than your skin.

Stars emit the X-rays and are collected with satellite detectors

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

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 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.

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.

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

Solar Panels- Electricity is needed for the instruments and to enable the spacecraft directional control

High Gain Antenna- Commands sent as radio waves to rotate satellite to position instruments in the direction we want them to see

Star Trackers - help satellites align themselves in the right direction

to acquire sources

Satellite Parts RXTE has three different

scientific instruments on it that observe slightly different energy ranges

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 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 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 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."

Quasi-Periodic Oscillations (QPOs)

http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/discovery_archive.html

Bibliography 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

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.

Darwin waited to see what evolved.

Edison thought it would be illuminating.

Einstein thought it would be relatively easy to attend.

Gauss was asked to attend because of his magnetic personality.

Hawking tried to string enough time together to make space in hisschedule.

Heisenberg was uncertain that he could make it.

Hertz said in the future he planned to attend with greater frequency.

Mendel said he'd put some things together and see what came out.

Newton planned to drop in.

Ohm resisted the idea.

Pavlov was drooling at the thought.

Pierre and Marie Curie were radiating enthusiasm.

Volta was electrified, and Archimedes buoyant at the thought.

Watt reckoned it would be a good way to let off steam.