Modeling SNR1987A with iHydra, II
Part 2, 7 April 2006 - dd
See also Part 1, March 2005
Introduction
HST optical image of '87A
Modeling SNR1987A with iHydra, II
Introduction |
HST optical image of '87A |
The LETG observations of Sept. 2004 have been analyzed by Zhekov et al. 2005 and 2006 and are fit well with two plane parallel shock components - interpreted as the slow shocks in the inward extending "fingers" (where the optical spots appeared) and reflected shocks in the shocked CSM material. A simple geomtrical model of these two spectral components is created and compared with the LETG data.
Note that other components not included (or needed) in the model could be: synchrotron X-ray emission (radio flux ~ 0.3 Jy at 1 GhZ at 2004.7; perhaps up to 0.4 Jy in 2007); shocked ejecta at the reverse shock; and faster forward shocks in less dense material.
Simple 3D model: view from above the ring plane (left) and in cross-section (right.)
The line-of-sight is shown by the dotted line.
Projected flux image as seen on the sky (below) in gray-scale and color coding.
Prototype code written in IDL was used, see the main routine:
The definition of the model geometrical/plasma components, the spectra assigned to some components, and the observations to be generated from the model are specified in the three files: The software makes use of "v3d" routines and other IDL code in the HAK distribution. (At MIT, in /nfs/cxc/a1/src/hak/hak_1.8/hak_code currently.)The real data from the ACIS observation 5579 and (the sum of two of) the Sept.04 LETG/ACIS observations are read as specified in the 'obs.rdb file using these two routines:
These two images show the system geometry from a "front" view
(left, perpendicular to the ring plane) and a "side" view.
The low-T component is assigned to discrete "spots", or
"fingers" or "protusions."
The high-T emission comes from a more extended region, divided
into two shells: an inner shocked-ejecta shell (brighter here) and
an outer shocked CSM region ending at the forward shock. The
dotted line is the line-of-sight to the observer.
A more 3D-ish rendering and a cross-section are shown in these
views:
The actual X-ray emission is shown here rendered
similarly to the full geometry above:
Finally, these two X-ray emitting components are projected
to the sky plane (45 degrees off the ring axis) and weighted
by their X-ray flux to generate an approximation to the expected
intensity distribution of the system seen in X-rays (by a telescope
of high spatial resolution):
The images above are useful to confirm/explore the model geometry. The same data structures that were used to create these images were then used to:
The volume and mass of the various components are given:
- - - - - - - - - - Fingers: Volume[10^57 cm^3], Mass[SM] = 1.60847e-06 0.0233284 CSM_shk: Volume[10^57 cm^3], Mass[SM] = 0.000188996 0.0555708 ej_shk: Volume[10^57 cm^3], Mass[SM] = 0.000160311 0.0452192 l-o-s: Volume[10^57 cm^3], Mass[SM] = 1.13933e-06 0.00000 - - - - - - - - - - MAX(n_e) = 5597.68 - - - - - - - - - -Note that the first three components are the X-ray emitting ones and their masses, 0.023, 0.056, 0.045 solar masses, are based on the source distance, emitting volume, electron and ion densities, and emission properties of the plasma they model. The "fingers" volume here is about 0.46% of the shock regions combined volumes.
The electron density is calculated through out the whole region and
plotted here i) for all locations as a 1D array over the whole
cube, and ii) just along the Y-axis, that is along the central
vertical line in the crosssection plots. Note the low density of the shocked
CSM/ejecta region, ~ 250 /cm^3, and the higher density of the shocked
"finger" regions, ~ 5000/cm^3.
Simulated events and observations are specified in an observation
table:
inst params obsid expos roll date product gotdata datapro calcmod method arf ------ ---- ----- ----- ----- ----- ------ ----- ------- ------- ------ --- ACIS S3 5579 35.7e3 335.21 2005.0 SkyEvts 1 ihy... 1 simple sn1987a_5579_arf.fits LETG LEGp1 4641+5362 140.e3 105.20 2004.7 Grat2D 1 sn19... 1 simple sn1987a_4641_leg1.garf LETG LEGm1 4641+5362 140.e3 105.20 2004.7 Grat2D 1 sn19... 1 simple sn1987a_4641_leg-1.garf LETG LEGp1 Cy08-300ks 900.e3 90.0 2007.7 Grat2D 0 - 1 simple sn1987a_4641_leg1.garf LETG LEGm1 Cy08-300ks 900.e3 90.0 2007.7 Grat2D 0 - 1 simple sn1987a_4641_leg-1.garf HETG MEGp1 Cy08-270ks 810.e3 90.0 2007.7 Grat2D 0 - 1 simple aciss_meg1_cy08.garf HETG MEGm1 Cy08-270ks 810.e3 90.0 2007.7 Grat2D 0 - 1 simple aciss_meg-1_cy08.garf HETG HEGp1 Cy08-270ks 810.e3 90.0 2007.7 Grat2D 0 - 1 simple aciss_heg1_cy08.garf HETG HEGm1 Cy08-270ks 810.e3 90.0 2007.7 Grat2D 0 - 1 simple aciss_heg-1_cy08.garf HETG zo Cy08-270ks 810.e3 0.0 2007.7 SkyEvts 0 - 1 simple aciss_hetg0_cy08.arf ACIS S3 Cy08-50ksS3 150.e3 0.0 2007.7 SkyEvts 0 - 1 simple aciss_aimpt_cy08.arfThe first three lines are the real ACIS and LETG observations, the rest are simulated observations with the exposure set to 3 times the value to account for the expected flux increase from '87A in the late 2006 / 2007 time frame as compared with the 2004.7 LETG observation.
Comparison of the "real" ACIS observation events (DATA) and
the simulated events (MODEL)
are shown
with their energy histograms (DATA=solid_green, MODEL=dotted_diamonds).
Comparison of the "real" LETG +1st
order observation events (DATA) and simulation (MODEL)
are shown here, including a K-S test-plot between them:
Comparison of the "real" LETG -1st
order observation events (DATA) and simulation (MODEL)
are shown here, including a K-S test-plot between them:
