Astronomy 496: Xray Astronomy

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Astronomy 496 X-ray Astronomy

• 8/30/02, Fri
• History of X-ray Astronomy
• The early years - before 1962
• The early history of X-ray sky
• 40 years of good X-ray astronomy

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E- Spectrum
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Absorptin and fluorescence
Absorption
Fluorescence
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The Early Years 1946 - 1962

• After WWII, Naval Research Lab (NRL) used V2
• rockets and photographic plate ? detected the
  Sun
• Sun at 1 AU, the nearest star at 1.3 pc
  2.7?105 AU
• Flux ? (distance)-2 ? Nothing else
  to observe!
• American Science Engineering (ASE) led by
• Riccardo Giacconi to search for X-rays
  from the
• Moon in order to study the lunar surface.
• - interaction with solar wind particles
• - fluorescence caused by solar X-ray flux
• 1961 October - rocket launched successfully,
• but detector door
  failed to open!
• 1962 June - 2 of the 3 Geiger counters worked
• - didnt detect the Moon
• - detected Sco X-1 at 100 photons cm-2
  s-1
• - X-ray scanners at airports by
  Astrophysical Lab

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American Science Engineering
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The Early Years 1946 - 1962

• After WWII, Naval Research Lab (NRL) used V2
• rockets and photographic plate ? detected the
  Sun
• Sun at 1 AU, the nearest star at 1.3 pc
  2.7?105 AU
• Flux ? (distance)-2 ? Nothing else
  to observe!
• American Science Engineering (ASE) led by
• Riccardo Giacconi to search for X-rays
  from the
• Moon in order to study the lunar surface.
• - interaction with solar wind particles
• - fluorescence caused by solar X-ray flux
• 1961 October - rocket launched successfully,
• but detector door
  failed to open!
• 1962 June - 2 of the 3 Geiger counters worked
• - didnt detect the Moon
• - detected Sco X-1 at 100 photons cm-2
  s-1
• - X-ray scanners at airports by
  Astrophysical Lab

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First Detection of Sco X-1
Gursky Oh, no!
7.0 mg/cm2 mica more absorption, only hard
X-rays 1.4 mg/cm2 mica less absorption, both
soft and hard X-rays
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An Early History of the X-ray Sky

• Herbert Gursky (ASE) detected Cyg X-1, Tau
  X-1
• Stu Bowyer (NRL) confirmed Tau X-1 using a
  rocket-
• borne detector, and identified it as
  the Crab Nebula
• George Clark (MIT) detected high-energy
  X-rays
• from the Crab Nebula using a
  balloon-borne detector
• 1964-1970
• Many rockets and balloons were used
  to explore the
• X-ray sky, 50 X-ray sources known
• Orbiting geological observatories to
  image the Sun.

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Missions launched before 1976
Uhuru, launched on the Independence Day of Kenya
- Dec 12, 1970, means freedom. It made the
first all-sky survey in X-rays with 339 sources
detected.
Uhuru ?
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The Physical Nature of X-ray Sources

• The angular resolution of X-ray detectors in the
  60s was
• A few degrees ? difficult to identify optical
  counterparts

Lunar occultation of the Crab Nebula - by Bowyer
1964
1974 Nov 3 by Palmieri et al.
(1975, ApJ, 202, 494)
Lunar motion 1 arcmin per min
? Pulsar 5 of the flux
120 sec
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The Physical Nature of X-ray Sources
What is Sco X-1?
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The Physical Nature of X-ray Sources
What is Sco X-1?
- Improvement of error box - 13 mag star, blue
color, irregular variability
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The Physical Nature of X-ray Sources

• Precise locations ? identify optical or radio
  counterparts
• X-ray spectra and light curves ? emission
  mechanisms
• Survey the sky for more sources

• Sco X-1 was not understood, although its
  optical counterpart
• was identified.
• Uhuru discovered a similar source Cen X-3
  (4U1118-60).
• 1967-1978 two surveys of the southern sky
• - Swift, Ghodil, et al. (Lawrence Livermore
  Lab, LLL)
• observed it twice and determined a rough
  location
• - Pounds et al. (Leicester) observed it
  twice, but didnt see it
• Both groups were right because Cen X-3 was
  highly variable!
• Uhuru observations made by Ethan Schreier
  (ASE) in 1971
• periodicity of 4.84 sec in X-ray flux ?
  rotating neutron star
• period varies slightly with time ? orbital
  period of 2.09 days
• neutron star is in an eclipsing binary
  system, B0Ib companion.

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The Physical Nature of X-ray Sources

• HMXB - high mass X-ray binaries (Cen X-3)
• LMXB - low mass X-ray binaries (Sco
  X-1)
• Neutron star or black hole normal star
• X-ray luminosity can be up to 1038 ergs/s !
• (L? 3.9?1033 ergs/s, L?, X 1026 - 1028
  ergs/s)
• Cataclysmic variables, dwarf novae (SS Cygni)
  White dwarf low mass normal star
• Active stellar coronae (Capella)
• T Tauri stars, white dwarfs, OB stars, late-type
  stars

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HEAO-1 All-Sky Survey
1977 Aug - 1979 Jan 0.2 keV - 10 MeV
Detected 842 sources (many extragalactic sources)
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HEAO-1 All-Sky Survey
1977 Aug - 1979 Jan 0.2 keV - 10 MeV
Detected 842 sources (many extragalactic sources)
?Sco X-1
Crab ?
? Cas A
? Galactic Center
? LMC
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ROSAT All-Sky Survey
1990 Jun - 1991 Jan 0.1 keV - 2 KeV
Detected 150,000 sources!
?Sco X-1
? Cas A
? Galactic Center
? LMC
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ROSAT All-Sky Survey
1990 Jun - 1991 Jan 0.1 keV - 2 KeV
Detected 150,000 sources!
?Sco X-1
? Cas A
? Galactic Center
? LMC
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ROSAT All-Sky Survey
1990 Jun - 1991 Jan 0.1 keV - 2 KeV
Detected 150,000 sources!
?Sco X-1
? Cas A
? Galactic Center
? LMC
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ROSAT All-Sky Survey
1990 Jun - 1991 Jan 0.1 keV - 2 KeV
Detected 150,000 sources!
?Sco X-1
? Cas A
? Galactic Center
? LMC