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Diffuse Galactic X-ray Emission & the Galactic Centre

Diffuse Galactic X-ray Emission & the Galactic Centre. Bob Warwick University of Leicester. Accreting Black-holes in the Nearby Galaxy M101. OPTICAL. X-RAY. A Normal Face-on Galaxy – M101. Why are X-rays Important?. Identified phases of the Galactic ISM:

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Diffuse Galactic X-ray Emission & the Galactic Centre

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  1. Diffuse Galactic X-ray Emission & the Galactic Centre Bob Warwick University of Leicester

  2. Accreting Black-holes in the Nearby Galaxy M101 OPTICAL X-RAY

  3. A Normal Face-on Galaxy – M101 Why are X-rays Important? • Identified phases of the Galactic ISM: • Very hot: log T > 7.5 i.e. KT > 3 keV. • Hot: 6 < log T < 7.5, i.e. 0.1 < kT < 3 keV • Coronal: 5 < log T < 6 • Warm: log T ~ 4, e.g. WIM, WNM. • Cold: log T 1 - 3 e.g. Molecular clouds 0.3-1.0 keV XMM-Newton source-removed EPIC image with GALEX UV contours superimposed (Warwick et al. 2005 in prep.)

  4. X-ray Emission from the Milky Way Type of Emitter Number in Summed Lx Galaxy 10 38 erg s-1 HMXRB 30 ~3 LMXRB 100 ~30 SNR ~500 <1 Low Lx Be Binaries ~104 <1 CVs ~105 <1 RSCVn ~106 <1 Late Type Stars 1010 <1 Active Nucleus 1 <0.001 Diffuse Disk/GC 1 ~3 Diffuse Bulge 1 ~20 Diffuse Halo/Corona 1 ~10 Total ~60

  5. 408 MHz Haslam et al. 1982 Snowden et al. 1997

  6. Chandra Mosaic of the Galactic Centre Region Wang, Gotthelf & Lang (2002)

  7. Topics • The Local Bubble, the Galactic Halo & Beyond • Loop 1 & the Galactic Bulge Emission • The Origin of the Hard Galactic Ridge • Hot Plasma in the Galactic Center Region • Fluorescent X-rays from GC Molecular Clouds

  8. Topics • The Local Bubble, the Galactic Halo & Beyond • Loop 1 & the Galactic Bulge Emission • The Origin of the Hard Galactic Ridge • Hot Plasma in the Galactic Center Region • Fluorescent X-rays from GC Molecular Clouds

  9. T = 106.5 K T = 106.1 K Distribution of ~ 106 K Plasma in the Local Galaxy Galactic Anti-Centre Galactic Centre GALACTIC PLANE Snowden (2002)

  10. Shadowing of the ¼ keV SXRB in Draco RAS ¼ keV IRAS 100 micron Burrows & Mendenhall 1991; Snowden et al. 1991

  11. Distribution of ~ 106 K Plasma in the Local Galaxy T = 106.5 K Draco Nebula T = 106.1 K 270o 90o Cygnus Super Bubble Snowden (2002)

  12. Simulated Spectrum of the Galactic Foreground at High Latitude • Local Hot Bubble • Active Galaxies • Galactic Halo • IGM of Local Group ? • WHIM ? Fang et al, 2005

  13. WHIM Absorption Along the Line of Sight to Markarian 421 Nicastro et al. (2005)

  14. Hot gas in a Galaxy Group Diffuse emission from a WHIM filament Void in the WHIM structure Fang et al, 2005

  15. XMM-Newton EPIC Instrument Large Effective Area: ~ 2000 cm2 @ 1 keV Good Imaging Capability: PSF(FWHM) 6 arcsec Wide Field of View: ~30 arcmin diameter Broad Bandpass: 0.3-12 keV Good Spectral Resolution: 120 eV @ 6 keV

  16. XMM MIRRORS

  17. XMM EPIC CCD CAMERAS MOS CCDs pn CCD

  18. Measuring the Spectrum of the Diffuse XRB with the EPIC CCDs pn Instrumental fluorescent lines MOS Particle continuum Energy (keV)

  19. WHIM FILAMENT Simulated Spectra

  20. Topics • The Local Bubble, the Galactic Halo & Beyond • Loop 1 & the Galactic Bulge Emission • The Origin of the Hard Galactic Ridge • Hot Plasma in the Galactic Center Region • Fluorescent X-rays from GC Molecular Clouds

  21. Distribution of ~106 K Plasma in the Local ISM T = 106.6 K T = 106.1 K Galactic Centre Galactic Anti-Centre Snowden (2002)

  22. ROSAT ALL-SKY SURVEY - ¾ keV IMAGE

  23. Soft X-ray Spectra of the North Polar Spur Willingale et al. (2003)

  24. Willingale et al. (2003)

  25. ROSAT ALL-SKY SURVEY - ¾ keV IMAGE Ophiuchus Dark Cloud

  26. X-ray Shadowing in the Ophiuchus Molecular Cloud EPIC PN SPECTRUM: ON/OFF CLOUD 0.2 Energy (keV) 1 2 Image: X-ray 0.5-0.9 keV Contours: IRAS 100 micron Mendes et al. (2005) reported in Breitschwerdt et al. (2005)

  27. ROSAT ALL-SKY SURVEY - ¾ keV IMAGE

  28. EPIC MOS SPECTRA FOR THE GALACTIC BULGE REGION 0.5,-2.6 0.0,0.0 1.1,-3.8 0.4,-5.4 0.5,-8.0 0.0,-11.9 345,+12 345,+24

  29. Topics • The Local Bubble, the Galactic Halo & Beyond • Loop 1 & the Galactic Bulge Emission • The Origin of the Hard Galactic Ridge • Hot Plasma in the Galactic Center Region • Fluorescent X-rays from GC Molecular Clouds

  30. 6. 7 keV line Excellent Tracer Galactic Center The Galactic X-ray Ridge Identified as a significant Galactic feature by HEAO1 (Worrall et al. 1982) Narrow ridge evident in EXOSAT Galactic Plane Scan (Warwick et al. 1985) Extensively studied in Ginga & ASCA Surveys (Yamauchi & Koyama 1993; Sugizaki et al. 2001)

  31. Spectrum of the Galactic Ridge • Emission lines from highly ionized Si, S, and Fe  multi-temperature plasma models • ORIGIN OF THE HARD COMPONENT? • Luminosity of 1.4 x 10^38 erg/s • Energy Density ~10 eV/cm^3 • Too hot to originate in SN activity • Unbound to Galactic Disk • Possible approaches to various aspects of the problem: • Magnetic reconnection & confinement • Quasi-thermal plasma • LECRe – non-thermal contribution • LECR ions & charge exchange • See Tanaka (2002) ASCA GIS 6.7 keV iron line kT ~ 10 keV Cosmic X-ray Background Cool component kT ~0.8 keV Kaneda et al. (1997)

  32. Point source contribution Ebisawa et al (2005) Is the Hard X-ray Galactic Ridge due to • Truly diffuse emission? • The superposition of point sources?

  33. Ebisawa et al. (2003,2005) Is the Hard X-ray Galactic Ridge due to • Truly diffuse emission? • The superposition of point sources?

  34. XGPS-I Survey after Point Source Removal 0.4-1.4 keV 2-6 keV

  35. G20.7-0.1 G20.0-0.2 G19.6-0.2 G21.8-0.2=Kes 69 Radio 20 cm XGPS-I Survey after Point Source Removal 2-6 keV

  36. Variation of the 2-6 keV surface brightness of the Galactic X-ray Ridge with (l,b) 25.0o 5.0o Galactic Longitude -0.5o 0.0o +0.5o Galactic Latitude

  37. The 6.7 keV iron line – the key diagnostic?ASCA GIS: 6.61+/-0.02 keV (Kaneda et al. 1997)  nei plasma or a blend of thermal emission with 6.4 keV iron fluorescence from LECRe excitation of cold gasASCA SIS: Blend of 6.70 keV (He-like) & 6.96 keV (H-like) lines (Tanaka 2002)  ~ collisional equilibrium thermal plasma at ~ 8 keV  very similar spectrum to that seen in Galactic Centre!Chandra: 6.52 +0.08/-0.14 keV (Ebisawa et al. 2005) consistent with ASCA GIS result!

  38. Equivalent width of 6.4 keV Fe fluorescence line < 50 eV 6.7 keV iron line The X-ray Spectrum of the Galactic X-ray Ridge measured by XMM-Newton Raw Background Background-subtracted Preliminary Only

  39. Topics • The Local Bubble, the Galactic Halo & Beyond • Loop 1 & the Galactic Bulge Emission • The Origin of the Hard Galactic Ridge • Hot Plasma in the Galactic Center Region • Fluorescent X-rays from GC Molecular Clouds

  40. XMM-NEWTON GALACTIC CENTRE SURVEYS WIDE-FIELD SURVEY Anne Decourchelle Saclay Bob Warwick Leicester Masaaki Sakano Leicester Peter Predehl MPE Delphine Porquet MPE SGR A* MONITORING Andrea Goldwurm Saclay et al ~ 250 ks ~ 400 ks

  41. 0.0o -0.2o 0.2o 0.0o Sgr A - Radio Arc Region 0.5-1.4 keV X-ray Sgr A* 1E 1743.1-2843 Galactic Latitude -0.2o Galactic Longitude

  42. 0.0o -0.2o 0.2o 0.0o Sgr A - Radio Arc Region 2-4.5 keV X-ray Arches Cluster Sgr A* 1E 1743.1-2843 Galactic Latitude Sgr A East SNR -0.2o Galactic Longitude

  43. 0.0o -0.2o 0.2o 0.0o Sgr A - Radio Arc Region 4.5-6 keV X-ray Arches Cluster Sgr A East SNR Sgr A* 1E 1743.1-2843 Galactic Latitude NT X-ray Threads -0.2o Galactic Longitude

  44. 0.0o -0.2o 0.2o 0.0o Sgr A - Radio Arc Region 6-9 keV X-ray Sgr A* Transient Transient Galactic Latitude NT X-ray Threads G0.13-0.13 Transient -0.2o Galactic Longitude

  45. 2-6 keV band 2.4 keV S line 6.7 keV Fe line 6.4 keV Fe line

  46. Spectral Extraction Region 4.5- 6 keV Continuum Celestial Coordinates

  47. X-ray Spectrum from the Annular Region around Sgr A Si XIII S XV 7-10 keV Thermal and/or Non-Thermal Ar XVII Ca XIX Fe 1-3 keV Thermal Al & Si Fluorescence Lines

  48. Intrinsic width of Fe 6.7 keV line 27 +/- 13 eV Fe-line Spectrum from the Annular Region around Sgr A 6.4 keV 6.70 keV 6.96 keV Fe XXV Fe Neutral Fe XXVI

  49. S XV Fe XXV Fe K 8 keV thermal 1 keV thermal Non-thermal bremmstrahlung plus 6.4 keV iron fluorescence from LECRe + molecular gas

  50. a x bx cx 4.5-6 keV Continuum 6.4 keV Iron Line 2.4 keV Sulphur Line 6.7 keV Iron Line

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