The Future of Xray Astronomy

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The Future of X-ray Astronomy

• Keith Arnaud
• NASA Goddard
• University of Maryland

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Theme
In the first 40 years of X-ray astronomy we
increased sensitivity by a factor of 109, image
resolution by 2.5x105, spectral resolution by
104. How do we keep this progress up for the next
40 years ?

• High sensitivity, high resolution spectroscopy.
• Polarimetry
• Interferometry

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Calorimetry
About 150 years ago, James Joule and Julius von
Mayer independently determined that HEAT
ENERGY, and calorimetry was born. But, only
about 20 years ago, the power of performing
calorimetric measurements at very low
temperatures (lt 0.1 K) was realized,
independently, by Harvey Moseley and by Etorre
Fiorini and Tapio Niinikoski. This is called
MICROCALORIMETRY, or occasionally QUANTUM
CALORIMETRY, because of its ability to measure
the energy of individual photons or particles
with high sensitivity.
Stahle
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X-ray calorimetry
Stahle
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Microcalorimeters vs. Gratings

• Resolutions comparable with gratings.
  Microcalorimeters win at high energies, gratings
  at low energies.
• Non-dispersive so
• high efficiency
• low background
• no problems for extended sources
• wide bandpass
• However, microcalorimeters are cryogenic
  experiments requiring cooling to 60 mK.

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A Multiwavelength Note

• Microcalorimeters were first developed for IR
  and are being used on IR astronomy space
  missions.
• They are also being used on optical telescopes -
  where they provide filter type spectral
  resolution without using filters.
• They are also used in laboratory dark matter
  searches.

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X-rays on Ice
The XRS X-ray microcalorimeter built for Astro-E
(the fifth Japanese X-ray astronomy satellite)
Resolution 9 - 12 eV FWHM (0.5 - 10 keV)
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Inserting the He dewar in the Ne dewar
A solid Ne dewar outside a liquid He dewar
outside an adiabatic demagnetization refrigerator.
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Astro-E Launch - February 2000
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20 seconds and going well
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Uh - oh
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You really dont want to see this
Astro-E is being rebuilt as Astro-E2 and will be
launched in Jan/Feb 2005. Rebuilt calorimeter now
has resolution of 6 eV.
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Laboratory Astrophysics with a Microcalorimeter
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Constellation-X
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Constellation-X Overview

• Use X-ray spectroscopy to observe
• Black holes strong gravity evolution
• Large scale structure in the Universe trace the
  underlying dark matter
• Production and recycling of the elements

• Mission parameters
• Telescope area 3 m2 at 1 keV
• 100 times XMM/Chandra for high res. spectra
• Spectral resolving power 300-3,000
• 5 times improvement at 6 keV
• Band pass 0.25 to 40 keV
• 100 times more sensitive at 40 keV

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Calorimeter development
120
100
Instrument Resolution 2.0 ? 0.1 eV FWHM
Al Ka1,2
80
Counts per 0.25 eV bin
60
40
Al Ka3,4
450 counts/sec
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0
1480
1485
1490
1495
1500
1505
Bismuth absorber
Energy (eV)
TES Al/Ag bilayer
K. Irwin
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XEUS

• ESA proposed mission for low Earth orbit.
• 6 m2 of collecting area at 1 keV.
• Imaging resolution goal of 2" HEW (Half Energy
  Width) at 1 keV.
• Limiting sensitivity 100 times deeper than
  XMM-NEWTON.

• Spectral resolution of 1 to 10 eV between 0.05
  and 30 keV.

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XEUS II

• After completion of the initial 4-6 year mission
  phase, XEUS will rendezvous with the ISS for
  refurbishment and adding extra mirror area.
• New detector spacecraft with next generation of
  focal plane technologies.
• Grown mirror will have 30 m2 collecting area at
  1 keV 3 m2 at 8 keV.
• Sensitivity 250 times better than XMM-NEWTON.

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Con-x
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Generation X

• Scientific goal to probe the X-ray emission
  from the universe at z 5-10.
• An effective area of 150 m2 at 1 keV with an
  angular resolution of 0.1 arc second.
• Detect sources 1000 times fainter than Chandra
  (flux limit of 2 x 10-20 ergs/cm2/s).
• Obtain high resolution spectra from sources
  100-1000 x fainter than observable by
  Constellation-X.
• Six identical satellites with 40 to 150 m focal
  length to L2.

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Telescope Evolution
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Why X-ray Polarimetry ?

• Because its there ! Whenever we look at the
  Universe in a new way we make unexpected
  discoveries.
• We expect polarization from X-ray synchrotron
  sources such as SNR and jets. Also from X-ray
  reflection in binaries and AGN.
• There is one detection of X-ray polarization -
  that of the Crab Nebula SNR.
• No X-ray polarimeter has flown on a satellite
  since the 1970s.
• There is a new idea for a more efficient
  polarimeter

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Polarization
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Electron Tracks
Bellazzini et al.
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Microwell detector
Bellazzini et al.
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Bellazzini et al.
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Accumulation of many events
Bellazzini et al.
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X-ray Interferometry

• While astronomical sensitivity has increased by
  a vast factor imaging resolution has not. HST is
  only 100 times better than Galileos telescope.
• To do better requires interferometry.
• Radio interferometry is well developed but
  baselines are very long and few sources have high
  enough surface brightness in the radio band.
• Optical interferometry is in the experimental
  stage and milliarcsec resolutions should be
  achievable.

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X-ray Interferometry II

• The X-ray band is the natural place for
  interferometry !
• Microarcsecond resolutions are possible with a
  baseline of 10 meters.
• X-ray sources have very high surface brightness
  on microarcsecond scales.
• X-ray interferometry allows virtual interstellar
  travel

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100 milliarcseconds
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10 milliarcseconds
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1 milliarcsecond
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100 microarcseconds
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10 microarcseconds
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1 microarcsecond
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Scientific Goals
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Laboratory test
Fringes at 8.35 Å 25 November 2002
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Test set-up at Goddard
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MAXIM Pathfinder
1 km
Science Phase 2 High Resolution (100 nas)
Science Phase 1 Low Resolution (100 mas)
Launch
200 km
20,000 km
Transfer Stage
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Timeline
2004 Swift 2005 Astro-E2 2007
Astrosat 2009? NeXT 2012?
Constellation-X 2015?? XEUS, Maxim
Pathfinder 2025??? Generation X, Maxim