1 / 12

Masayoshi Nobukawa, Katsuji Koyama, Takeshi Go Tsuru, Syukyo G Ryu (Kyoto Univ.)

Discovery of K a lines of neutral S, Ar, Ca, Cr, & Mn atoms from the Galactic center with Suzaku. Masayoshi Nobukawa, Katsuji Koyama, Takeshi Go Tsuru, Syukyo G Ryu (Kyoto Univ.). Neutral Fe line from the Galactic center Discovery of neutral K a lines of S, Ar, Ca, Cr, Mn

Download Presentation

Masayoshi Nobukawa, Katsuji Koyama, Takeshi Go Tsuru, Syukyo G Ryu (Kyoto Univ.)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Discovery of Ka lines of neutral S, Ar, Ca, Cr, & Mn atoms from the Galactic center with Suzaku Masayoshi Nobukawa, Katsuji Koyama, Takeshi Go Tsuru, Syukyo G Ryu (Kyoto Univ.) • Neutral Fe line from the Galactic center • Discovery of neutral Ka linesof S, Ar, Ca, Cr, Mn • What is the origin of the neutral lines ? • Summary Galactic center workshop 2009, shanghai, hope hotel

  2. Neutral Fe line emission from the GCregion 6.4 keV (neutral Fe-Ka) emission shows a clumpy distribution in the Galactic center region. Neutral clumps are correlated with giant molecular clouds (Sgr B2, Radio Arc regions…) X-ray binary 1E 1743.1-2843 6.4keV map Sgr A East (SNR) Sgr B2 Sgr B1 M0.74-0.09 Sgr B2 20’ (50 pc) Radio Arc G0.174-0.233 Sgr B2 Radio Arc Sgr B2 Neutral iron line Molecular gas CS (J=1-0) Spectrumof Sgr B2 ・prominent neutral Fe line ・strongly absorbed continuum (NH~1024 cm-2) 3 4 5 6 7 8 Energy (keV)

  3. Other neutral lines ? Lighter elements, S, Ar, Ca, Cr, Mn are expected to exist in the molecular cloud. S Fe=1 Ar Ca Ni Cr Mn We searched for the neutrallines from these elements using the Suzaku satellite. *solar abundance 3/11 Low energy K-Shell lines are absorbed by an ISM.

  4. The strongest neutral clump Neutral Fe S Si Ar Fe Ca He, H-like lines mainly come from hot plasma Other neutral lines are weak. (Ratio to Fe is < 0.01—0.1) => The brightest neutral clump in the GC region 6.4keV map Sgr A East (SNR) Sgr B2 Sgr B1 M0.74-0.09 selected region Sgr B2 20 arcmin Radio Arc G0.174-0.233 Blue: neutral Red: plasma components

  5. Spectral fitting of the 6.4 keV clump X-ray emission from the GC region: (Koyama+07, Ryu+09) 2 temp. plasma kT~ 1 keV plasma (He, H-like Si, S, Ar, Ca) kT~ 7 keV plasma (He-, H-like Fe, Ni) neutral clump (lines + continuum) Fitting model: 2 temp. plasmas (kT~1 keV + 7 KeV) neutral component (lines + continuum) Abs (ISM) Abs (MC) x x We added He-like Cr, Mn lines (APEC does not contain) Firstly, neutral lines; only Fe Ka, Kb + Ni Ka

  6. NH(ISM) =7.1(±0.3)x1022cm-2 (Typical for the GC sources) S Ar Ca Cr Mn kT1 = 0.99 ± 0.02 keV kT2 = 7.02 ± 0.33 keV Z(Si) = 1.3 ± 0.1 solar Z(S,Ar,Ca) = 1.6 ± 0.1 Z(Fe/Ni) =1.2/2.1(fixed) (Koyama+07) He-like Cr, Mn lines are firstly detected !! neutral lines: Fe-Ka, Kb, Ni-Ka continuum: NH(MC) = 1.7 ± 0.3 x1023 cm-2 G = 1.85 ± 0.15 These residuals correspond to neutral Ka line of S, Ar, Ca, Cr, Mn. (90% errors)

  7. Blue: neutral Red: plasma Fe Mn S Ar Cr Ca Ni without S, Ar, Ca, Cr, Mn lines c2 = 355/208 c2 = 243/203 with S, Ar, Ca, Cr, Mn lines 7/11

  8. Discovery of neutral S, Ar, Ca, Cr, Mn lines Observed line intensity graph 90% errors Observed Line intensity S Ar Ca Cr Mn Fe Ni We successfully detected fluorescence Ka lines of these elements from the GC. 8/11

  9. Origin of the neutral lines: X-ray/Electron Neutral line: neutral atoms must be ionized by external X-rays / electrons. Continuum: Thomson scattering (X-ray) Bremsstrahlung (electron) Line emission External X-ray / electron molecular cloud NH = 1023 cm-2 Continuum Assumptions: uniform density of the MC solar abundance index of 2 (X-ray) / 3 (electron) <= observed photon index of ~2 Different processes would make different spectra. => We calculated the spectra with Geant4 Mn Cr S Fe Fe Ca Ar Equivalent width is a key to distinguish the two scenarios 9/11

  10. Equivalent width and the origin X-ray origin Preliminary This result may suggest the X-ray origin. electron origin 90% errors *Calculated EWs depend on metal abundances, geometry, and energy index of incident radiations

  11. Summary Suzaku(4Msec) Red: 0.5-2 keV Green: 2-5 keV Blue: 5-8 keV We successfully detected fluorescence K-shell lines from S, Ar, Ca, Cr, Mn from the brightest neutral clump of the Galactic center. Equivalent Widths of the neutral lines would suggest the X-ray origin rather than the electron origin.

More Related