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Jenny Carter LXO Basic Feasibility 15 July 2007 Basic Feasibility for the LXO Jenny Carter.

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Presentation on theme: "Jenny Carter LXO Basic Feasibility 15 July 2007 Basic Feasibility for the LXO Jenny Carter."— Presentation transcript:

1 Jenny Carter LXO Basic Feasibility 15 July 2007 Basic Feasibility for the LXO Jenny Carter

2 Jenny Carter LXO Basic Feasibility 15 July 2007 Basis for this study •Base on model of Robertson and Cravens, GeoPhys Res. Letters, Vol. 30, No. 8, 1439, X-ray emission from the terrestrial magnetosheath •Max – 8.8 keV cm -2 s -1 sr -1 •MCP optic plus MOS type CCD cameras at focal plane •Plan to model this instrument concept using Xspec to find expected count rates, signal-to-noise etc.

3 Jenny Carter LXO Basic Feasibility 15 July 2007 Selected areas •Select various FOV and calculate flux within the relevant solid angle FOV (º) Solid Angle (str) Flux keV s -1 cm -2 / ergs s -1 cm -2 5 x / 7.90× x / 2.31× x / 8.83× x / 1.70×10 -9

4 Jenny Carter LXO Basic Feasibility 15 July 2007 Effective area •Create arf using LOBSTER bkg effective area curve (Simon Vaughan, •(Improvement on previous work, adapting MOS arf for MCP optic, lack of RGA etc.)

5 Jenny Carter LXO Basic Feasibility 15 July 2007 Model basis •Snowden et al., HDFN and SWCX, ApJ, 610, 1182, 2004 •Use Snowden response matrix initially •SWCX lines, plus use background components •Relative normalisations taken from Snowden paper. LineEnergy (keV) C VI0.37 C VI0.46 O VII0.56 O VIII0.65 O VIII0.81 Ne IX0.91 Mg XI1.34

6 Jenny Carter LXO Basic Feasibility 15 July 2007 Spectra and Bkg •Fake spectra, sky bkg and particle background separately •Use MOS response matrix and lobster effective area •Scale each spectrum to match the flux in Robertson and Cravens model between 0.2 and 2 keV •Sky background assumed to be 10 photons cm -2 s -1 sr -1 at 1 keV, approx. value from Lumb et al., 389, 93, 2002, scale accordingly •Scale particle background so that crosses sky background at 5 keV Sky: wabs * (raymond + powerlaw + raymond) + vapec + raymond Sky: MW-halo, local halo, cosmic bkg, local hot bubble PB: powerlaw PB: particle induced background

7 Jenny Carter LXO Basic Feasibility 15 July 2007 Limitations, extra bkg •No lunar background considered •Instrumental lines, depending on instrument used etc. •Local and temporal variations in the sky background •Specifics of particle induced background dependent on instrumental set up etc.

8 Jenny Carter LXO Basic Feasibility 15 July 2007 Results – using MOS response

9 Jenny Carter LXO Basic Feasibility 15 July 2007 Results – response matrix adapted

10 Jenny Carter LXO Basic Feasibility 15 July 2007 Results – off centre selection

11 Jenny Carter LXO Basic Feasibility 15 July 2007 Results Summary FOV (º) PosTime (ks) CR – S (ct s -1 ) CR – Sky (ct s -1 ) CR – PB (ct s -1 ) S/N 9x9C C C x30C C C x9O O O

12 Jenny Carter LXO Basic Feasibility 15 July 2007 Simulated images of fov •Andy Read; based on predicted count rates and distribution of model, distribute photons for different exposure times 1 ks, magnetosheath, sky bkg

13 Jenny Carter LXO Basic Feasibility 15 July 2007 More images 1 ks, resultant, smoothed

14 Jenny Carter LXO Basic Feasibility 15 July 2007 More images (2) 10 ks 100 ks

15 Jenny Carter LXO Basic Feasibility 15 July 2007

16 Jenny Carter LXO Basic Feasibility 15 July 2007

17 Jenny Carter LXO Basic Feasibility 15 July 2007

18 Jenny Carter LXO Basic Feasibility 15 July 2007

19 Jenny Carter LXO Basic Feasibility 15 July 2007 LOBSTER optic designed for primary science goal as an ASM so optimises telescope grasp (fov x effective area) For LXO we would enhance soft X-ray sensitivity: f = 50 cm gives useful 9 0 x 9 0 fov in a compact form. Eff. Area of nickel- coated glass MCP optic of varying focal lengths


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