the focusing optics x-ray solar imager (foxsi) steven christe 1, s. krucker 2, l. glesener 2, s....
TRANSCRIPT
The Focusing Optics X-ray Solar Imager (FOXSI)
Steven Christe1, S. Krucker2, L. Glesener2, S. Ishikawa3, B. Ramsey4, T. Takahashi3, R.P. Lin2
1 NASA GSFC, Greenbelt, MD2 Space Sciences Lab, UCB, Berkeley, CA3 Dept. of Physics, U. of Tokyo, Japan4 NASA MSFC, Huntsville, AL
Basic flare model.
Basic Flare Model
Upward beams
Accelerationsite
Downward beams
Chromospheric evaporation
HXR observations of flare-acceleration electrons Provide quantitative
measurements Depend on ambient
density Strongest from
footpoints Very faint emission
from corona RHESSI does not have
high enough sensitivity or dynamic range
HXR focusing optics can provide it.
HXR observations of Flare Model
Upward beams
Accelerationsite
Downward beams
Chromospheric evaporation
HXR
HXR
n = 109 cm-3
n = 1011 cm-3
n = 1011-12
cm-3
SXR
HXR observations of flare-acceleration electrons Provide quantitative
measurements Depend on ambient
density Strongest from
footpoints Very faint emission
from corona RHESSI does not have
high enough sensitivity or dynamic range
HXR focusing optics can provide it.
HXR observations of Flare Model
Upward beams
Accelerationsite
Downward beams
Chromospheric evaporation
HXR
HXR
n = 109 cm-3
n = 1011 cm-3
n = 1011-12
cm-3
SXR
HXR
HXR observations of flare-acceleration electrons Provide quantitative
measurements Depend on ambient
density Strongest from
footpoints Very faint emission
from corona RHESSI does not have
high enough sensitivity or dynamic range
HXR focusing optics can provide both
HXR observations of Flare Model
Upward beams
Accelerationsite
Downward beams
Chromospheric evaporation
HXR
HXR
n = 109 cm-3
n = 1011 cm-3
n = 1011-12
cm-3
SXR
HXR
Present day observations show mostly footpoints.
HXR observations of Flare Model
Upward beams
Accelerationsite
Downward beams
Chromospheric evaporation
n = 109 cm-3
n = 1011 cm-3
n = 1011-12
cm-3
SXR
RHESSI HXR Obs.
HXR
HXR
60
arcsec
HXR focusing optics provides imaging of the acceleration region
And track electrons in the corona.
HXR observations of Flare Model
Upward beams
Accelerationsite
Downward beams
n = 109 cm-3
n = 1011-12
cm-3
SXR
HXR
HXR
Chromospheric evaporation
n = 1011 cm-3
HXRs from up and down beamsH
XR
Flu
x
Acceleration site
Height above the photosphere [arcsec]
ratio of footpoint to coronal emission depends on: coronal density electron spectrum photon energy trapping time
but it is generally large
Dynamic range: ~400
HXRs from up and down beamsH
XR
Flu
x
Height above the photosphere [arcsec]
?emission from acc. region?trapping?
Acceleration site
Dynamic range: ~400
ratio of footpoint to coronal emission depends on: coronal density electron spectrum photon energy trapping time
but it is generally large
Optics Performance
-100
-50 0 50
100
150arcsec
FWHM 10’’HPD 25’’
Point Spread Function (PSF)
Current Tech: slumped glass optics, replicated metal optics
Best resolution currently available by B. Ramsey (NASA MSFC)
Individual shell resolution: 7 arcsec (FWHM)
Telescope module resolution: 10-12 arcsec
Dynamic range: 30 arcsec:
~10050 arcsec:
~500
Metal optics
-1
0
-2-3-4-5
Log(r
ela
tive
flu
x)
Dynamic range will allow us to image coronal HXR emission in the presence of HXR footpoints
Footpoints will be unresolved, but can be separated for larger flares
Basic Flare Model
Upward beams
Accelerationsite
Downward beams
n = 109
cm-3
n = 1011 cm-3
n = 1011-12
cm-3
SXR
5000
3000
1000
700
250
100
20
90”
78”
66”
54”
42”
30”
18”
6”
Dynamic Range
60
arcsec
HXR
HXR
HXRs from escaping electrons
Assuming 100 cm2
Dt=1 s
Dt=30 s
Assuming 100 cm2
2-4 kg/cm2 (e.g. 50 kg of optic = 100-200 cm2)
Jets
Quiet Sun network flares(coronal heating)
Active Region Flares
Radio bursts from shocks
Energetic Electrons
Type III radio bursts
CME
Position sensitive solid state (Si, CdTe, CZT) Energy resolution 0.2 to 2 keV (1-100 keV) Current Technology
Focal Plane Detectors
Type Pixels Pitch Range Heritage
Si (strips) 128 x 128
75 um 1-20 keV Astro-H HXI, FOXSI
CdTe (strips) 128 x 128
250 um 5-80 keV Astro-H HXI, FOXSI2
CZT 64 x 64 600 um 5-80 keV NuSTAR
CdTe 256 x 256
250 um 2-80 keV HEXITEC
Parameter Value
Focal length 10 m
Energy Range 1-80 keV
Energy resolution ~1 keV
Spatial resolution 7 arcsec
Dynamic Range Up to 100 x RHESSI
Sensitivity 100 x RHESSI
Cost SMEX-like
FOXSI Mission ConceptThis mission concept is based on existing technology.
Currently FOXSI is a sounding rocket (launch Oct. ‘12). HEROES balloon launch in Sept ’13.
The future may bring better spatial resolution, lighter optics, etc.FOXSI will observe electrons as
they are being accelerated in the corona, along which field line they travel away from the acceleration site, where they are stopped, and how some electrons escape to be detected as SEPs at Earth.
Fin