ARISEVSOP2 Jim Ulvestad

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ARISE/VSOP-2Jim Ulvestad

• ARISE Mission Science Drivers
• Changes in Science and Mission
• VSOP-2 Status
• VSOP-2 Partnerships and Outlook

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ARISE Mission

• Space Very Long Baseline Interferometry mission
• Proposed 25m antenna, operating at frequencies up
  to 86 GHz, in elliptical orbit with apogee height
  of 40,000 km
• Resolution better than 20 microarcseconds
• AANM cost estimate of 350 million
• Biggest technical challenge was to make the 25m
  aperture accurate enough to operate at 86 GHz
• Deployable or inflatable antenna?
• Planning assumed only 8 aperture efficiency at
  86 GHz

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ARISE Science Drivers

• AANM
• Supermassive black holes and relativistic jets
• Maser sources in Milky Way and other galaxies
• Q2C
• What is the nature of dark energy?
• How do cosmic accelerators work and what are they
  accelerating?

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Science Changes

• Massive black holes now more closely linked to
  galaxy evolution
• Magnetic fields increasingly viewed as being
  critical in acceleration and collimation of
  relativistic cosmic jets
• WMAP cosmology has greatly refined cosmological
  parameters, but finding more accurate value of H0
  is critical for removing degeneracies in
  determination of w, Om

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WMAP Constraints on Om, O?

• WMAP alone constrains relation between Om and O?,
  but does not strongly constrain their absolute
  values
• Knowledge of H0 to better than 5 is critical

Spergel et al. 2006
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Constraining w by Constraining H0
Spergel et al. 2006
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AGN Unification (Antonucci ARAA 1993)

• Broad-line AGN (Type 1) if seen down the jet
  axis
• Narrow-Line AGN (Type 2) if seen from the side
• Many new SDSS Type II AGNs

• Peck, Taylor, Conway 1999

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NGC 4258

• H2O megamaser emission associated with nuclear
  torus
• Direct measurement of BH mass of 39 million MSun
• Geometric distance of 7.4 Mpc
• Can we find distances further out in the Hubble
  flow, and determine the Hubble Constant to better
  than 3 accuracy?

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Spectra of H2O Maser Disks to 100 Mpc
Braatz et al., in preparation (using GBT)
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M87 Inner Jet
M87 Base of Jet 43 GHz Global VLBI Junor,
Biretta, Livio Nature, 401, 891
VLA Images
Resolution 0.?00033?0.?00012
Black Hole / Jet Model
VLBI Image
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Where Most X-rays ?-rays Are Emitted
clouds
X-rays ?-rays
Invisible?
Radio core
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Mission Changes

• ARISE was behind Constellation-X and LISA in NASA
  roadmaps
• No significant chance of flying ARISE in the next
  10-15 years
• JAXA has approved VSOP-2 as a full-scale
  scientific mission, with planned launch in
  February 2012
• 3.5 times the ground resolution for 22 GHz H2O
  masers
• At least 13 radio AGNs with resolution better
  than 200 Schwarzschild radii

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Observing Parameters
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VSOP-2 Status

• VSOP-2 approved as science mission by JAXA
• Strong budget limit of 100 million, not
  counting launch vehicle and some ISAS salaries
• Excellent development/planning process for the
  deployable antenna
• Heritage from ETS-VIII, to be tested later this
  year
• Growing East Asian VLBI community

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Mesh Antenna Segment in Development
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ETS-VIII Deployment Test

• ETS-VIII scheduled for launch in next six months
• ?/50 at 2.3 GHz
• Deployment mechanism the same as VSOP-2 antenna
• VSOP-2 will have additional on-orbit adjustment
  mechanisms

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VSOP-2 Partnerships/Outlook

• Space VLBI inherently requires international
  partnerships, and needs 3 primary U.S.
  contributions
• Worldwide tracking stations needed to bring down
  1 Gbps science data in real time
• Few-cm orbit determination needed for water maser
  science and high-frequency observing
  (GPSaccelerometer)
• Worldwide ground radio telescopes needed to
  provide significant imaging capability
• U.S. telescopes are dominant for the
  high-frequency science (22 and 43 GHz)
• U.S. telescopes will provide most ground
  baselines of at least a few thousand km

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VSOP-2 observation
2 Gbps/Max
PC DISK
FEDEX
1 Gbps
Correlator
IP/Network
Total Data Size 2 Gbps x observing time x
Number of Antenna
IP/Network
Typical Observation Observing time 12
hours Number of antennas 11
121.6 T byte / 1 observation (12 h)
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VSOP-2 Science Outlook

• VSOP-2 is a huge observational step toward the
  capabilities envisioned for ARISE, and has the
  potential to deliver significant results on its
  primary science goals
• Determine H0 to 3-5 (depending on systematic
  errors), to break degeneracy in cosmology models
• Image changes in the flaring blazars seen by
  GLAST
• Image jet collimation within 200 Schwarzschild
  radii of a number of nearby black holes
• U.S. contribution to VSOP-2 will greatly improve
  the fundamental science of the mission, provide
  scientific access to the U.S. community, and
  fulfill the AANM recommendation, for a small
  fraction of the ARISE cost