1. X-ray Emission due to Charge Exchange between Solar Wind and Earth Atmosphere on September 12 2005 Hironori Matsumoto (Kobayashi-Maskawa Institute, Nagoya University) 1. Suzaku Observation Figure 1: Suzaku image in the 0.4 – 2.0 keV band (XIS0+1+2+3): (left) Sep.12, 2005, (right) Jan. 26, 2006. Spectra and light curves in the following analysis are extracted from the green circle excluding the inner ellipse Suzaku observed a sky region at (α, δ) J2000 = (14h58m34s, - 42d23m51s) on Sep. 12, 2005 and on Jan. 26, 2006 for to obtain background data for SN1006 observations. XIS images of these observations in the 0.2-2keV band are shown in Figure 1. 2. X-ray Light Curve Figure 2 shows X-ray light curves (XIS1) in the 0.3 – 2.0 keV and 2.0 – 7.0 keV bands obtained from the circular region shown in Figure 1. While the count rate in the 2.0-7.0 keV band on Sep. 12, 2005 was almost the same as that on Jan. 26, 2006, the count rate in the 0.3 – 2.0 keV band on Sep. 12, 2005 was twice as large as that on Jan. 26, 2006. Moreover, a large flare can be seen in the 2.0—7.0 keV band at 9:30 (UT) on Sep. 12, 2005. Figure 2: XIS1 light curve in the 0.3—2.0 keV and 2.0—7.0 keV bands: (left) Sep. 12, 2005, (right) Jan. 26, 2006 3. X-ray spectrum Suzaku Exposure Coincident with the flare observed with Suzaku. Figure 3: X-ray light curve of Sun observed by the GOES satellite. There was M6.1 flare at 9:30(UT) on Sep. 12, 2005. The spectrum on Jan. 26, 2006 can be explained by two-temperature plasma of kT=0.2keV and 0.7keV and cosmic X-ray background, phenomenologically. Figure 4: XIS1 spectra on Sep. 12, 2005 excluding the flare (red) and on Jan. 26, 2006 (black). Figure 5: XIS1 spectrum on Sep. 12, 2005: (red) spectrum of the flare, (black) spectrum excluding the flare. Figure 6: X-ray spectrum on Sep. 12, 2005 (excluding the flare) and the best-fit model. Red: FI(XIS1), Black: FI (XIS0+2+3) Table 1: Identification of the emission lines found in the spectrum shown in Figure 6. The spectrum on Sep. 12, 2005 can be explained by adding many emission lines to the model describing the spectrum on Jan. 26. 2006 (Figure 6, Table1) Most of the emission lines are identified as characteristic X-rays from highly ionized atoms such as C, N, O, Ne, Mg, and Si. Sun was very active around Sep. 10, 2005. SOHO detected an X2.1 flare and CME at 22h, Sep 10, 2005 (UT) and an M3.1 flare and CME at 12h30m, Sep 11, 2005. ACE observed that the speed of the solar wind was ~1000km/s on Sep. 12, 2005, while that on Jan. 26. 2006 was ~500km/s. High ionized atoms in the solar wind (X q+ ) interacts with neutral atoms (Y) in Earth’s atmosphere, and the charge exchange occurred between them. The charge exchange resulted in excited ions (X *(q-1)+ ), and characteristic X-rays were emitted from them. X q+ + Y  X* (q-1)+ + Y + excited X (q-1)+ Ground state Characteristic X-rays We detected more emission lines than Fujimoto et al. 2007, Ezoe et al. 2010, and Ezoe et al. 2011. Abstract A sky region at (α, δ) J2000 = (14h58m34s, -42d23m51s) was observed with Suzaku on September 12, 2005 and January 26, 2006. The X-ray flux below 2 keV of the 1 st observation was larger than that of the 2 nd observation. The X-ray spectrum on Sep. 12, 2005 can be explained by adding many emission lines to the spectrum on Jan. 26, 2006. Most of these emission lines are identified as characteristic X-rays from highly ionized ions of C, N, O, Ne, Mg, Si. The activity of Sun was high on Sep. 12, 2005, and the solar wind from active Sun interacted with Earth’s atmosphere. The charge exchange interaction between the highly ionized atoms in the solar wind and neutral atoms in Earth’s atmosphere resulted in the X-ray emission lines. Sep. 12, 2005 Jan. 26, 2006 flare Figure 4 shows X-ray spectra (XIS1) on Sep. 12, 2005 (excluding the flare; red) and Jan. 26, 2006(black). There is a large difference below 2keV. The red spectrum in Figure 5 is the spectrum of the flare on Sep 12, 2005 (red), while the black one shows the spectrum excluding the flare. There is a larger difference above 2keV, and we can see very strong instrumental emission line from Al at 1.48 keV.