FI2+BI2 or FI3+BI3?--from scientific point of view--

Hironori Matsumoto (Kyoto Univ.)

Effective Area (1 sensor)

BI CCD FI CCD

From response files for AO-1

EA:FI2+BI2vsFI3+BI1

Log scale Linear scale

EA ratio: FI2+BI2vsFI3+BI1Log scale Linear scale

My scientific interests: early-type galaxiesM87 (SWG target) 50ks exposure

brightest CD galaxy (Fx=1.2e-10cgs)

With what uncertainties can we determine parameters?

FI2BI2 FI3BI1

NH +/-1.2% +/-1.6%

kT +/-0.15% +/-0.18%

O +/-3.8% +/-4.4%

Fe +/-0.58% +/-0.80%

NGC4406 (SWG target) 50ks exposure 3rd brightest early-type galaxy (Fx=6.0e-12cgs)

FI2BI2 FI3BI1

NH +/-2.9% +/-3.4%

kT +/-0.48% +/-0.52%

O +/-6.9% +/-8.3%

Fe +/-3.0% +/-3.3%

MEKAL flux +/-2.9% +/-3.0%

Hard component

flux+/-4.7% +/-4.8%

If NGC4406 has 1/10 X-ray flux?i.e. typical flux of early-type galaxies.

FI2BI2 FI3BI1

NH +/-11% +/-13%

kT +/-1.6% +/-1.7%

O +/-27% +/-29%

Fe +/-10% +/-11%

MEKAL flux +/-9.7% +/-11%

Hard component

Flux+/-23% +/-17%

50ks exposure

Conclusion

As for the observations of early-type galaxies, which emit X-rays within the entire XIS band pass, the two combinations (FI2+BI2 and FI3+BI1) make no difference.

We should determine which combination we employ from the technical point of view (reliability, endurance etc.), not from the scientific point of view.