Science Goals with theX-Ray Imager
Ed DeLucaNGXRT Sub Working GroupSpectroscopy tells what is happening, imaging
tells you where and why (Golub)

Coronal Instrumentation• Grazing Incidence X-Ray Telescope- Broad temperature response- High sensitivity to coronal plasma- Highest resolution 0.5 “/pixel- Photon counting would provide temperature and density- Minimum temperature ~1MK
• Normal Incidence EUV/UV Telescopes- Narrow temperature response- Requires large effective area
- Highest resolution 0.1”/pixel, (0.02”/pixel is possible)- Multiple passbands are required see the whole corona- Chromospheric and Transitions Region passbands are possible

NASA Heliophysics Vision• Open the frontier to space environmental prediction- Understand the fundamental physical processes of the spaceenvironment - from the sun, to the earth, to other planets andbeyond to the interstellar medium.

• Understand the nature of our home in space- Understand how human society, technological systems, and thehabitatbility of planets are affected by solar variability
interacting with planetary magnetic fields and atmospheres• Safeguard the journey of exploration- Maximize the safty and productivity of human and robotic

explorers by developing the capability to predict the extreme
and dynamic conditions in space.

Plan-B science goals• Trace energy flow at natural dynamic solar time scales over a large

dynamic range from the photosphere into the corona through small
spatial-scale elementary solar structures and determine the resulting
large-scale structures (Understand the physics of the beta = 1 region)• Understand physical processes such as magnetic dissipation andreconnection in astrophysical plasmas, under a wide variety of physicalconditions.

• Understand and spatially resolve elementary atmospheric structures

over each temperature domain of the atmosphere and determine how
they are created and evolve• Understand how small-scale physical processes initiate large scale
dynamic phenomena creating space weather• Understand how physical processes alter coronal properties such asvariations in its composition• Understand the mechanisms of particle acceleration in space andastrophysical plasmas

Plan-B Science & HP Roadmap• Plan B science is closely aligned with the understanding offundamental physical processes.

• The NASA/Heliophysics strategic mission line that addresses
fundamental physics is the Solar-Terrestrial Probe line.
Hinode is an S-T Probe. The current Roadmap has thefollowing missions in the S-T Probe line

- Magnetospheric Multi-Scale Mission (2014)- Origins of Near Earth Plasma (2018)- Solar Energetic Particle Acceleration and Transport (2021)- Ion-Neutral Coupling in the Atmosphere (2025)• This summer NASA will ask the National Research Council

to start a Decadal Survey of HP, it will take about 2-years

Coronal Science Basis Vectors• Dynamical - Origins, energetics and plasma diagnostics- Waves- Flows- Particle Acceleration• Topological - Stability and heating- Magnetic Free Energy- Helicity- Quasi-Separtrix Surfaces• Thermal - Magnetic, plasma and radiative sources/sinks- Heating/Cooling- Thermal Instabilities- Non-Equlibirum Ionization- Elemental Abundances

Instrumentation Requirements• Dynamical - Origins, energetics and plasma diagnostics- High resolution in space and time - throughput is important.
- Temperature coverage - we need to see the plasma- See non-thermal emission• Topological - Stability and heating- Temperature coverage- FOV large enough to understand the magnetic boundary conditions• Thermal - Magnetic, plasma and radiative sources/sinks- Distinguish hot plasma from cold plasma- Follow the thermal evolution of the plasma- Identify non-thermal plasma

Jets - A Universal Example• Dynamical - Have seen flows and waves in jets.
- What is the contribution of non-thermal particles tothe energy budget?

• Topological - Basic topology is understood- What is the role of helicity in the energetics?
• Thermal - How does energy flow from the corona tochromosphere?

Science Flow Down - GI• The flow of energy from the photosphere into thecorona- Required measurements✴ High resolution, high sensitivity photospheric and chromosphericmagnetograms, combined with high-resolution, high-sensitivity, highcadence coronal imagery and plasma diagnostics.

- Example✴ Jets - Define the magnetic structure before the jet: free energy,
helicity and topological connections. Observe the reconnection
between emerging flux and overlying flux. Measure the plasmaenergy during the jet, both thermal and kinetic.

- X-Ray Observations✴ Integrating: 3-4 filters (0.5 - 3.0MK) cadence of 30s✴ Photon counting: morphology image every 30s , spectrum every 1-2minutes

Science Flow Down - GI
• Diagnostics of reconnecting plasma- Required measurements✴ Time evolution of the hot plasma (possibly in non-ionization

equilibrium), evaporated chromospheric plasma, radiative instabilities
and cooling plasma.

- Example✴ Post flare loop arcade- X-Ray Observations✴ Photon Counting: 2000 photon spectra with a 30s cadence over100”x100” FOV (200x200 0.5” pixels).

Science Flow Down - GI
• Connections to the Heliosphere- Required measurements✴ Measure the flow of low density high temperature plasma into theheliosphere. Measure the evolution of the closed and open fields
above active regions.

- Example✴ Non-flare active region at the limb. Coronal hole jets & Plumes- X-Ray Observations✴ Photon Counting: 10,000 photon spectra with a 3600s summed
exposure over 100”x100” FOV (200x200 0.5” pixels).

✴ Integrating: 1-2 filters, summed images at the limb.

Science Flow Down - GI
• Particle Acceleration- Required measurements✴ Image the non-thermal electrons from small reconnection events.

Need to be able to distinguish thermal and non-thermal spectra at~6KeV.

- Example✴ Active region transiant brightenings. The background plasma

temperature is about 3MK. A very common reconnection phenomena.

- X-Ray Observations✴ Photon Counting: Accumulate spectra with 2000 photons at 30s
cadence in 100"x100" fov (200x200 pixels at 0.5"/pixel).

Science Flow Down - NI
• The flow of energy from the photosphere into thecorona- Required measurements✴ High resolution, high sensitivity photospheric and chromosphericmagnetograms, combined with high-resolution, high-sensitivity, highcadence coronal imagery and plasma diagnostics.

- Example✴ Jets - Define the magnetic structure before the jet: free energy,
helicity and topological connections. Observe the reconnection
between emerging flux and overlying flux. Measure the plasmaenergy during the jet, both thermal and kinetic.

- X-Ray Observations✴ Multiple passband observations with emphasis on high sensitivity

observations of the high chromosphere, transition region and low
coronaScience Flow Down - NI
• Diagnostics of reconnecting plasma- Required measurements✴ Time evolution of the hot plasma (possibly in non-ionizationequilibrium), evaporated chromospheric plasma, radiative instabilities
and cooling plasma.

- Example✴ Post flare loop arcade- X-Ray Observations✴ Multi-filter observations with emphasis on coronal wavelengths.

Science Flow Down - NI
• Connections to the Heliosphere- Required measurements✴ Observations of outflows along loops connecting to the heliosphere.
Observations are needed at multiple temperatures. High sensitivity
required to observe low density plasma.

- Example✴ Active region and coronal hole limb observations- X-Ray Observations✴ Take images in 304, 465, 171, 195, 211 at 30s cadence. Flows can behigh speed (~100 km/s) but are observed on long loops (~100").
Observe for 2 hours. FOV is 200"x200" (or 2000x2000 pixels at0.1"/pixel).

Science Flow Down - NI
• Elementary Structures in the Corona- Required measurements✴ High spatial and temporal resolution observations to detect thesubstruction of coronal loops: braiding, resonant absorptions, islands.

- Example✴ Non-flare active region loops.

- X-Ray Observations✴ Multi-wavelength observations - may take high cadence in 1-2

passbands at a time, ~6 passbands needed for full temporature
coverage.

Science Flow Down - NI
• Particle Acceleration- Required measurements✴ Footpoint dynamics - UV images at high resolution and high cadence✴ Footpoint depth - determine the depth of energy deposition fordifferent magentic field configurations.

- Example✴ Flare foot point spreading - indentify the locations of particle impact
for joint observations with chromospheric spectrographs.

✴ Flare foot point spreading - Simultanious multi-wavelength
observations of particle impacts UV and moss brightening.

- X-Ray Observations✴ Imaging in a single UV passbands✴ Imaging in UV, 171, 304 and 465 passbands, high cadence in eachpassband is needed.

Conclusions• GI Telescope without Photon Counting- High Cadence observations of coronal plasmas, broad FOVs
- Limited temperature resolution- Limited spatial resolution• GI Telescope with Photon Counting- Simultaneous imaging and X-ray spectroscopy- Technology development may be needed- Limited spatial resolution• NI Telescopes- High spatial resolution- Need multiple telescopes- Need large effective area

Concerns• Is the proposed set of Plan-B instruments

consistent with the capabilities of the program?

• The resources have not been defined, but thepresent instrument compliment is vast.

• What are the one or two critical measurementsthat we need to be able to make for Plan-B to becompelling?